CN109033664A - Based on the considerations of the architectural wind environment appraisal procedure of CFD building body draining effect - Google Patents

Abstract

The embodiment of the invention provides the architectural wind environment appraisal procedures based on the considerations of CFD building body draining effect, using porous media unit simulation target structures monomer, and then simulate whole building group, the research that windowing mode is carried out to the target structures monomer model constructed is not needed, but it is used as window by the porous of porous media unit, target structures monomer is studied.For building " gas permeability " building concentration, improving urban architecture monomer simulation precision has positive effect.Method proposed in the embodiment of the present invention is reduced significantly compared with outdoor scene indoor shielding object three-dimensional simulation calculation amount, it is expected to buildings in general and block scale (< 1km) that high-precision CFD numerical simulation calculates being advanced into city scale (< 10km), is city planning design person and the science evidence that government decision Resources for construction Sustainable type city provides.

Description

A CFD-based assessment method for building wind environment considering the effect of building through-flow

technical field

Embodiments of the present invention relate to the technical field of fluid mechanics building wind environment, and more specifically, relate to a CFD-based method for assessing building wind environment considering the effect of building through-flow.

Background technique

With the development of society and the acceleration of the urbanization process, the construction process of urban medium and high-rise buildings not only needs to consider the air circulation of the building itself, but also the changes in the wind environment caused by the building. The high-rise buildings become the path for the wind to pass through, and the narrow wind passage forms a "laneway effect", which makes the wind speed in this area significantly faster, causing unsafe and uncomfortable problems for pedestrians in the process of walking and activities.

At present, the research on the dynamic diffusion mechanism of buildings is usually carried out in two ways: wind tunnel simulation test and computer numerical simulation of wind environment. Among them, the wind tunnel simulation test (wind-tunnel testing) refers to placing aircraft or other object models in the wind tunnel to study the gas flow and its interaction with the model to understand the aerodynamic characteristics of the actual aircraft or other objects. A simulation method for aerodynamic experiments. Computational Fluid Dynamics (CFD) numerical simulation is mainly used for computer numerical simulation of wind environment. Compared with wind tunnel simulation test, CFD numerical simulation has lower cost and shorter time consumption, and it is easier to obtain rich flow field result information, and It is easier to conduct sensitivity analysis on parameter changes, and it is easier to simulate more complex real flow conditions. There have been a lot of work on building wind environment simulation.

However, although the wind tunnel simulation test can accurately deduce the building wind environment, the environment required for the experiment is large and the instruments are expensive, so it is not suitable for testing the simulation needs under different environmental parameters. Although CFD numerical simulation has advantages that wind tunnel simulation tests do not have, it is limited by the imperfection of turbulence theory itself, the scope of application of turbulence models, and the adaptability of calculation methods, so the reliability of CFD numerical simulation is still low It needs to be verified by later experiments, which increases the complexity. Moreover, it is necessary to determine a suitable turbulence model for each different building, which greatly increases the amount of calculation.

Contents of the invention

In order to overcome the above problems or at least partly solve the above problems, an embodiment of the present invention provides a CFD-based building wind environment assessment method considering the effect of flow through a building body.

On the one hand, the embodiment of the present invention provides a method for assessing the building wind environment based on CFD numerical simulation considering the effect of building through-flow, including:

Based on the porous media unit, carry out computational fluid dynamics CFD numerical simulation on the target building unit with the target porosity, determine the wind speed in the calculation domain and the pressure drop between the air inlet and the air outlet in the calculation domain, so as to evaluate the target The flow field and pressure drop around the building unit; the porous media unit has a preset inertial resistance coefficient and a preset viscous resistance coefficient;

Wherein, when performing the CFD numerical simulation, a porous medium unit model is established, and the control equation and the momentum equation source term of the porous medium unit model in the calculation domain are determined;

Based on the control equation and the source term of the momentum equation, determine the flow field and pressure drop around the porous media unit model, and use the determined flow field and pressure drop around the porous media unit model as the target building Flow field and pressure drop around a monomer.

On the other hand, an embodiment of the present invention provides a building wind environment assessment system based on CFD numerical simulation considering the effect of building through-flow, including:

The wind environment assessment module is used to perform computational fluid dynamics CFD numerical simulation on the target building unit based on the porous media unit, determine the wind speed in the calculation domain and the pressure drop between the air inlet and the air outlet in the calculation domain, so as to evaluate the The flow field and pressure drop around the target building unit; measure and calculate that the porous medium unit has a preset inertial resistance coefficient and a preset viscous resistance coefficient when representing a building unit;

Wherein, when performing the CFD numerical simulation, a porous medium unit model is established, and the control equation and the momentum equation source term of the porous medium unit model in the calculation domain are determined;

Based on the control equation and the source term of the momentum equation, determine the flow field and pressure drop around the porous media unit model, and use the determined flow field and pressure drop around the porous media unit model as the target building Flow field and pressure drop around a monomer.

The CFD-based building wind environment assessment method considering the flow-through effect of the building body provided by the embodiment of the present invention uses porous media units to simulate the target building unit, and does not need to study the window opening mode of the constructed target building unit model , but with the porous medium unit as a window, the target building unit is studied. It is of positive significance for the construction of "breathable" building units and the improvement of the simulation accuracy of urban building units. The method proposed in the embodiment of the present invention greatly reduces the calculation amount of 3D simulation of occlusions in real scenes, and is expected to advance the general building and block scale (<1km) calculated by high-precision CFD numerical simulation to the urban scale (<10km) , to provide scientific evidence for urban planners and government decision-making to build resource-sustainable cities. It solves the problem of which urban underlying surface layout and shape (building monomer, building group and street shape) are conducive to the dynamic diffusion of atmospheric particles, and provides a scientific basis for urban atmospheric environment planning and design.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic flow chart of a CFD-based building wind environment assessment method considering building through-flow effects provided by an embodiment of the present invention;

Fig. 2 is a structural schematic diagram of the calculation domain of a CFD-based building wind environment assessment method considering the building body through-flow effect provided by the embodiment of the present invention;

Figure 3(a) is a flow field pressure field curve of the first type of sample porous media unit with a porosity of 10% in a CFD-based building wind environment assessment method considering the building body through-flow effect provided by the embodiment of the present invention Fig. 3 (b) is the flow field pressure field curve of the first type sample porous medium unit with a porosity of 20% in a kind of building wind environment assessment method based on CFD considering the building body through-flow effect provided by the embodiment of the present invention Fig. 3 (c) is the flow field pressure field of the first type sample porous media unit with a porosity of 30% in a kind of building wind environment assessment method based on CFD considering the building body through-flow effect provided by the embodiment of the present invention Graph;

Figure 4(a) is a schematic diagram of the flow field and pressure field curves of the cuboid second type sample porous medium unit in a CFD-based building wind environment assessment method considering the building body through-flow effect provided by the embodiment of the present invention; Figure 4 ( b) is a schematic diagram of the flow field and pressure field curve of the second type of cube sample porous media unit;

Fig. 5(a) is the distribution of the first type of flow field when the wind direction is parallel to the normal line of the windward side and the wind speed is 2m/s in a CFD-based building wind environment assessment method considering the effect of building through-flow provided by the embodiment of the present invention. Figure 5(b) is a CFD-based building wind environment assessment method considering the building through-flow effect provided by the embodiment of the present invention, when the wind direction is parallel to the normal line of the windward side and the wind speed is 2m/s The contour diagram of the second type of flow field distribution, Fig. 5(c) is the angle between the wind direction and the normal line of the windward surface in a CFD-based building wind environment assessment method considering the building body through-flow effect provided by the embodiment of the present invention The contour map of the first type of flow field distribution when the wind speed is 135° and the wind speed is 4m/s, Figure 5(d) is a CFD-based building wind environment assessment considering the effect of building through-flow provided by the embodiment of the present invention In the method, the contour map of the second type of flow field distribution when the angle between the wind direction and the normal line of the windward side is 135° and the wind speed is 4m/s;

Figure 6(a) shows the distribution of the third type of flow field when the wind direction is parallel to the normal line of the windward side and the wind speed is 2 m/s in a CFD-based building wind environment assessment method considering the effect of building through-flow provided by the embodiment of the present invention Figure 6(b) is a CFD-based building wind environment assessment method considering the building through-flow effect provided by the embodiment of the present invention, when the wind direction is parallel to the normal line of the windward side and the wind speed is 2 m/s The contour map of the fourth type of flow field distribution, Fig. 6(c) is the angle between the wind direction and the normal line of the windward surface in a CFD-based building wind environment assessment method that considers the building body through-flow effect provided by the embodiment of the present invention The isoline map of the third type of flow field distribution when the wind speed is 45° and the wind speed is 4m/s. Figure 6(d) is a CFD-based building wind environment assessment considering the effect of building through-flow provided by the embodiment of the present invention In the method, the contour map of the fourth type of flow field distribution when the angle between the wind direction and the normal line of the windward side is 45° and the wind speed is 4m/s;

Fig. 7 is a structural schematic diagram of a CFD-based building wind environment assessment system considering the effect of building through-flow provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

As shown in Figure 1, an embodiment of the present invention provides a method for assessing building wind environment based on CFD numerical simulation considering the effect of building body flow, including:

S1, based on the porous media unit, perform computational fluid dynamics CFD numerical simulation on the target building unit with the target porosity, determine the wind speed in the calculation domain and the pressure drop between the air inlet and the air outlet in the calculation domain, so as to evaluate the The flow field and pressure drop around the target building unit; the porous media unit has a preset inertial resistance coefficient and a preset viscous resistance coefficient;

Wherein, when performing the CFD numerical simulation, a porous medium unit model is established, and the control equation and the momentum equation source term of the porous medium unit model in the calculation domain are determined;

Based on the control equation and the source term of the momentum equation, determine the flow field and pressure drop around the porous media unit model, and use the determined flow field and pressure drop around the porous media unit model as the target building Flow field and pressure drop around a monomer.

Specifically, in order to solve the technical problems existing in the prior art in the embodiment of the present invention, the porous medium unit is used to perform computational fluid dynamics CFD numerical simulation on the target building unit, so as to evaluate the flow field and pressure drop around the target building unit, That is to evaluate the wind environment around the target building monomer.

When using porous media units to simulate target building units, for each target building unit, which has a specific target porosity, it is necessary to use porous media units with preset inertial resistance coefficients and preset viscous resistance coefficients. That is to say, the values of the preset inertial resistance coefficient and the preset viscous resistance coefficient have a direct correspondence with the target porosity.

What needs to be explained here is that the calculation domain refers to the size of the area that needs to be studied in the CFD numerical simulation, which is usually as large as the outer border of the windward side of the porous media unit (that is, the vertical section), and the front and rear depths are respectively extended by 3-5 times that of the porous media unit. A region formed by the spatial distance of the side lengths of the media elements in which the porous media elements are set.

In the embodiment of the present invention, the porous medium unit is used to simulate the target building unit. It is not necessary to study the window opening mode of the constructed target building unit model. research. It is of positive significance for the construction of "breathable" building units and the improvement of the simulation accuracy of urban building units. The method proposed in the embodiment of the present invention greatly reduces the calculation amount of 3D simulation of occlusions in real scenes, and is expected to advance the general building and block scale (<1km) calculated by high-precision CFD numerical simulation to the urban scale (<10km) , to provide scientific evidence for urban planners and government decision-making to build resource-sustainable cities. It solves the problem of which urban underlying surface layout and shape (building monomer, building group and street shape) are conducive to the dynamic diffusion of atmospheric particles, and provides a scientific basis for urban atmospheric environment planning and design.

On the basis of the foregoing embodiments, the porous medium unit model established in the embodiments of the present invention includes a physical model and a mathematical model, specifically as follows:

When the research object is a porous medium unit, it is considered that the flow resistance per unit area of the fluid passing through the porous medium unit is constant and uniform. It needs to be realized by adding the source term to the momentum equation in the mathematical model of the porous medium unit. In the embodiment of the present invention, the volume average technique and the Reynolds time-averaged equation method are used to establish a porous medium unit suitable for urban turbulent flow and heat exchange. mathematical model. Determine the fluid velocity before passing through the porous media unit, the pressure on the wall (windward side) of the porous media unit, and the pressure on the wall (leeward side) of the porous media unit after passing through the porous media unit, according to the flow velocity before entering the hole - the pressure after entering the hole The method for determining the physical properties of a porous media element model, where the quantitative relationship between flow velocity and pressure drop varies depending on the pore morphology and porosity of the porous media element. The control equation in the embodiment of the present invention refers to the continuity equation of fluid flow, the momentum equation of the porous medium unit model, the energy equation of the porous medium unit model, and the like.

The continuity equation for fluid flow is:

where γ is the porosity of the porous medium, ρ _q is the fluid phase density of q-phase, α _q is the volume fraction of q-phase, is the q-phase velocity vector, To characterize mass transfer from p-phase to q-phase, To characterize mass transfer from phase q to phase p, S _q is the momentum resistance source term.

The momentum equation for the porous media element model:

Among them, μ _q is the q-phase shear force, λ _q is the q-phase viscosity coefficient, is the external body force on the porous media unit under the q-phase condition, is the lift force on the porous media unit under the q-phase condition, is the wall lubrication force of the porous media unit under the q-phase condition, is the imaginary mass force on the porous media unit under the q-phase condition, is the turbulent dispersion force of the porous media unit under the q-phase condition (it is not 0 only in the case of turbulent flow, and is 0 in other cases). P is the interaction pressure between p and q phases. Indicates the transmission speed between p and q phases, if is greater than zero, representing the mass transfer from p-phase to q-phase, then if is less than zero, representing mass transfer from q-phase to p-phase, then is the interaction force between p and q phases, depends on friction, pressure, cohesion and other effects, and is affected by conditions, is the pressure-strain tensor of the q-phase, C _2,q is the inertial resistance coefficient of the q-phase porous media unit, and K _q is the thermal conductivity of the solid phase.

The last item in formula (2) is the momentum resistance source item in the porous media unit, which is composed of viscous loss item and inertial loss item.

The standard energy transport process of the porous media unit is simulated by using the equilibrium thermal model equation, that is, the thermal equilibrium state is set for both the porous media unit and the fluid flow. where the conduction flux uses the effective conductivity and the transient term includes the thermal inertia of the solid region over the medium. The energy equation of the porous media element model is shown in formula (3):

Among them, γ is the porosity of the fluid-solid two-phase medium; Q _sp is the heat transfer coefficient between the solid surface and the q-phase fluid in the porous media unit. Assuming only convective heat transfer, the expression is:

Q _sp = (1-γ)α _q h _{q, eff} (T _s -T _q ) (4)

where _hq,eff is the effective convective heat transfer coefficient of phase _q , _Ts is the solid surface temperature in the porous media unit, and Tq is the temperature of the fluid in phase q.

From formula (3) and formula (4), it can be obtained that the expression of the momentum resistance source term used to simulate the porous media unit is shown in formula (5).

Among them, S _i is the source term of the momentum equation in the i-th dimension, which consists of two parts: the viscous loss item (that is, the first item on the right side of the equal sign in formula (5)) and the inertial loss item (that is, the second item on the right side of the equal sign in formula (5) item). |v| represents the absolute value of the fluid velocity, ρ is the density of the fluid, and μ is a constant with a value of 1.7894×10 ^-5 . The value of i is x, y, z, which represents each dimension in the three-dimensional space; the value of j is 1-3, which also represents each dimension in the three-dimensional space.

Assuming that the porosity of single-phase flow (or two-phase flow) is isotropic, the empirical expression of the porous media unit is:

Among them, 1/α is the viscous resistance coefficient, C ₂ is the inertial resistance coefficient, the matrix formed by D _ij in formula (5) can be expressed by the diagonal matrix 1/α, and the matrix formed by C _ij can be expressed by the diagonal matrix C ₂ express.

The characteristics of the porous media unit are described by the flow field v-pressure drop Δp, and the pressure loss parameter is calculated. The formula is as follows:

Δp=-S _i d=k ₁ v ² +k ₂ v (7)

Among them, Δp is the pressure drop between the windward side and the leeward side of the porous media unit, v is the flow velocity of the fluid, ρ is the density of the fluid, and d is the thickness of the porous media unit.

Substituting formula (6) into formula (7) and comparing with formula (7) can be obtained,

Under the condition that the values of other parameters are determined, the inertial resistance coefficient C ₂ and the viscous resistance coefficient 1/α of the porous media unit can be determined according to formula (8).

Among them, the obtained pressure drop and velocity data can be used as the physical characteristics of the porous media element model.

On the basis of the above embodiments, the preset inertial resistance coefficient and the preset viscous resistance coefficient are determined according to preset parameters, and the preset parameters are determined based on preset software.

Specifically, the purpose of the embodiment of the present invention is to determine a method that can quickly determine the preset inertial resistance coefficient and the preset viscous resistance coefficient. The preset inertial resistance coefficient determined by the method provided in the example and the porous medium unit corresponding to the preset viscous resistance coefficient can simulate a fixed type of building unit. The specific determination method is to use preset parameters to determine, and the preset parameters can include one of the porosity, the shape parameters of the building unit, the wind environment where the building unit is located, or the layout parameters of the building unit in the corresponding calculation domain. one or more species.

On the basis of the above-mentioned embodiments, the preset inertial resistance coefficient and the preset viscous resistance coefficient can be specifically calculated as follows:

Based on the preset software, construct a 3D model of a porous media unit with a target porosity to simulate a target building unit with a target porosity, and determine the calculation domain and boundary conditions;

calculating the flow field and pressure drop of the three-dimensional model based on the three-dimensional model of the porous media unit having the target porosity, the computational domain, and the boundary conditions;

According to the flow field and pressure drop of the three-dimensional model, the quantitative relationship between the flow field and the pressure drop of the porous media unit is determined, and the inertial resistance coefficient and the viscous resistance coefficient of the porous media unit are determined.

Specifically, the preset software used in the embodiment of the present invention to build a three-dimensional model can be SpaceChaim, NX (UG), AutoCAD or SketchUp pro, and the preset software used for CFD numerical simulation can be ANSYS FLUENT, for the porous media unit ANSYS DiscoveryLive can be used as a preset software for simulating a single building for verification. Specifically, appropriate software can be selected according to the complexity of the object that needs to build a three-dimensional model. This is not specifically limited in the embodiment of the present invention, and only SpaceChaim19.0 is used as an example for illustration. The method for determining the preset inertial resistance coefficient and the preset viscous resistance coefficient provided in the embodiment of the present invention is specifically realized only by using the parameter of porosity, that is, the preset inertial resistance coefficient and the preset viscous resistance coefficient are determined according to the porosity The ratio is determined, and the porosity is determined based on preset software. Specific steps are as follows:

S11. Firstly, in SpaceChaim19.0 software, carry out three-dimensional modeling of the target building unit, the model is a window mode, and construct a three-dimensional model of a cuboid porous media unit with the target porosity to simulate the target building unit with the target porosity. body.

S12, establish the calculation domain, which is as large as the outer border of the windward side of the porous medium unit (ie, the longitudinal section), and the front and rear depths are respectively extended by a space distance of 3-5 times the side length of the porous medium unit. Note that the calculation domain larger than the longitudinal section of the porous media unit cannot be done here, because when measuring the wind speed and pressure drop of the air inlet surface of the porous media unit, it must be ensured that all the inlet air passes through the interior of the building ventilation duct, and if it passes through the outside of the building, then The result is inaccurate.

S13, setting boundary conditions. Import the constructed 3D model and calculation domain into ANSYS FLUENT, set the wind speed of the wind environment to 4 m/s, the wind speed in the upper and lower spaces is the same, and the direction of the wind speed is parallel to the normal of the windward surface of the porous media unit. At the leeward side of the porous media unit (that is, the outlet boundary of the wind), the wind pressure is set as a reference value of 1 atmosphere. In ANSYSFLUENT, set the turbulent flow model to "k-epsilon" mode; the surface of the porous media unit is set to no-slip boundary, and the material of the porous media unit is set to "solid".

It should be noted that the material of the porous media unit for which the boundary conditions are set is "solid", which is different from the "build" of the fluid. The boundary conditions are divided into four categories: INLET, OUTLET, INTERNAL, and WALL according to the type. The partitions and fluid objects are classified correspondingly. Fluids are generally classified into INTERNAL, and solid walls are classified into WALL.

S14, the solver is initialized and calculated. After the parameters are set, the flow field and pressure drop indicators of the porous media unit are calculated.

If the target porosity in S11 is 10%, after S12-S14, determine the quantitative relationship between the flow field and pressure drop obtained in S14, that is, perform parameter fitting on the flow field and pressure drop, for example, the following formula ( 9) The binary quadratic equation shown has:

y＝83.767x ² +3.1136x+M (9)

Among them, y represents the flow field value, that is, the wind speed value in the flow field, the unit is m/s; x represents the pressure drop, the unit is pa; M is a constant, here M is 0, because the wind speed of 0m/s corresponds to The pressure drop is 0pa, so the constant term M in the fitting equation is 0.

Then there are:

Among them, C ₂ is the inertial resistance coefficient of the porous media unit, 1/α is the viscous resistance coefficient of the porous media unit, d is the thickness of the porous media unit, ρ is the fluid density, μ is a constant, and the value is 1.7894*10 ^-5 .

When d=9.49m and fluid density (ie air density) ρ is 1.225kg/m ³ , C ₂ =14.4112, 1/α=18335.3 can be obtained. That is to say, the preset inertial resistance coefficient and the preset viscous resistance coefficient of the porous media unit are obtained.

On the basis of the above-mentioned embodiments, the building wind environment assessment method based on CFD numerical simulation provided in the embodiments of the present invention also includes between S12 and S13:

S121. Determine a boundary and a minimum grid unit. Import the built 3D model and calculation domain into ICEM CFD19.0, select the calculation domain facing the windward side and the leeward side of the porous media unit, first create the air inlet (IINLET), air outlet (OUTLET), wall (WALL), interior ( INTERIOR) is the computational domain interface, followed by the establishment of "volume units", respectively "BUILDING" and "FLUID", which are the smallest volume units for constructing building entities and fluids. Set the diameter of each hole of the porous media unit to 0.004, set the maximum value (Max element) of the global mesh (Global Mesh) to 0.002, and set the minimum mesh size (Part Mesh) to "0.004/5=0.0008". What needs to be explained here is that the setting of the minimum grid size is the result of balancing the two factors of calculation efficiency and result quality.

S122, setting a grid type and a grid generation method. The grid type is "Quad Dominant", and the grid calculation method is "Patch Dependent". Execute the generate grid command to generate 2 million grids.

Correspondingly, when setting the boundary conditions in S13, the grid and computational domain of the 3D model generated in S122 are imported into ANSYS FLUENT for subsequent processing. See S13 for details of the specific process, which will not be repeated here in the embodiments of the present invention.

In the following, whether the porosity, the morphological parameters of the building unit, the wind environment of the building unit or the layout parameters of the building unit in the corresponding calculation domain can be used as preset parameters will be specifically explained and experimentally verified. How to determine the preset parameters.

On the basis of the above-mentioned embodiments, the preset parameters in the building wind environment assessment method based on CFD numerical simulation provided in the embodiments of the present invention are determined by the following determination method:

Based on the preset software, construct a three-dimensional model of multiple first-type sample porous media units with the same shape and different porosity, so as to simulate sample building units with different porosities, and determine the calculation domain and boundary conditions;

Calculate the flow field and pressure drop of each first type sample porous media unit based on the three-dimensional models of the first type sample porous media units, the calculation domain and the boundary conditions;

According to the flow field and pressure drop of each first type sample porous media unit, respectively determine the quantitative relationship between the flow field and pressure drop of each first type sample porous media unit, and respectively determine the porous media unit of each first type sample The inertial resistance coefficient and viscous resistance coefficient of the medium unit;

If the inertial resistance coefficients of each first-type sample porous media unit are different, and the viscous resistance coefficients of each first-type sample porous media unit are different, then the target porosity of the target building unit is used as the the preset parameters described above.

Specifically, S21, in SpaceChaim19.0 software, the three-dimensional modeling of the building monomer is carried out. The model is in the window mode, and three cuboid porous media units of the same shape (ie, the same size) and different porosities are respectively constructed (ie, the first sample-like porous media unit), and correspondingly obtained three 3D models. It should be noted that when the porous media unit simulates the building unit, the porous media unit can only simulate the building unit with the same porosity as the porous media unit.

S22. Establish a calculation domain, which is as large as the outer frame of the windward side of the porous medium unit of the first type of sample (ie, the longitudinal section), and the front and rear depths are respectively extended by 3-5 times the space distance of the side length of the porous medium unit of the first type of sample. Note that the calculation domain whose longitudinal section is larger than the porous media unit of the first type of sample cannot be done here, because it must be ensured that all the incoming air passes through the interior of the building ventilation duct, and the result will be inaccurate if it passes through the outside of the building. As shown in Figure 2, the area enclosed by the air inlet ①, the air outlet ①', and the air inlet ②, the air outlet ②' is the calculation domain, and the three-dimensional Model.

S23. Determine the boundary and the minimum grid unit. Import the 3D model and calculation domain into ICEMCFD19.0, select the calculation domain facing the windward side and the leeward side of the porous media unit of the first type of sample, and first create the windward side air inlet (IINLET), the leeward side air outlet (OUTLET), and the wall (WALL) and interior (INTERIOR) are computational domain interfaces, followed by the establishment of "volume units", respectively "BUILDING" and "FLUID", which are the smallest volume units for constructing building entities and fluids. Set the diameter of each hole in the first type of sample porous media unit to 0.004, set the maximum value (Maxelement) of the global mesh (Global Mesh) to 0.002, and set the minimum mesh size (Part Mesh) to "0.004/5= 0.0008". What needs to be explained here is that the setting of the minimum grid size is the result of balancing the two factors of calculation efficiency and result quality.

S24, setting a grid type and a grid generation method. The grid type is "Quad Dominant", and the grid calculation method is "Patch Dependent". Execute the generate grid command to generate 2 million grids. It should be noted that, when performing grid division by software, the 3D model and the computational domain are divided into tetrahedron grids (tetrahedron) or polyhedron grids (polyhydra) respectively.

S25, import the built 3D model and calculation domain into ANSYS FLUENT, set the wind speed of the wind environment to 4 m/s, the wind speed in the upper and lower spaces is the same, and the direction of the wind speed is parallel to the normal of the windward surface of the porous medium unit of the first type of sample . At the leeward side of the porous media unit of the first type of sample (that is, the outlet boundary of the wind), the wind pressure is set as a reference value of 1 atmosphere. In ANSYS FLUENT, the turbulence model is set to "k-epsilon" mode; the surface of the first type of sample porous media unit is set to no-slip boundary, and the material of the first type of sample porous media unit is set to "solid".

S26, the solver is initialized and calculated. After the parameters are set, calculate the flow field and pressure field of the first type of sample porous media unit.

As shown in FIG. 2 , in the three-dimensional model of the first type of sample porous medium unit used in the embodiment of the present invention, the three-dimensional model is a cuboid, and the cross-sectional shape in the length direction is a square. The length of the three-dimensional model is 12.65m, the width (that is, the thickness of the porous media unit of the first type sample) and the height of the three-dimensional model are both 9.49m, and the distance between every two ventilation windows in the length direction is 1.73m. The distance between every two ventilation windows in the height direction is 1.62m, and the shape of the ventilation windows is a square with a side length of 1m.

The flow and pressure field curves of the first type of sample porous media unit are calculated, as shown in Figure 3, where Figure 3(a) shows the flow field and pressure field curve of the first type of sample porous media unit with a porosity of 10%. The quadratic coefficient is k ₁ =83.767, the first power coefficient is k ₂ =3.1136, the thickness of the first type of porous medium used is 9.49m, and the air density is 1.225kg/m ³ , the inertial resistance can be obtained according to the formula (8) The coefficient _C2 is 14.4112, and the viscous resistance coefficient 1/α is 18335.3. Fig. 3(b) shows the flow field and pressure field curve of the first type sample porous media unit with a porosity of 20%. The quadratic coefficient is k ₁ =16.992, and the first power coefficient is k ₂ =25.385. The thickness of the sample porous medium is 9.49m, and the air density is 1.225kg/m ³ . According to formula (8), the inertial resistance coefficient C ₂ is 2.92329, and the viscous resistance coefficient 1/α is 149487. Figure 3(c) shows that the second power coefficient of the flow field pressure field curve of the first type of sample porous medium unit with a porosity of 30% is k ₁ =7.4124, and the first power coefficient is k ₂ =0.173. The first type of The thickness of the sample porous medium is 9.49m, and the air density is 1.225kg/m ³ . According to formula (8), the inertial resistance coefficient C ₂ is 1.27522, and the viscous resistance coefficient 1/α is 1018.76.

From the results of the inertial resistance coefficient and viscous resistance coefficient obtained above, it can be known that the inertial resistance coefficient and viscous resistance coefficient of each first-type sample porous media unit are different, and the target porosity of the target building unit can affect the inertial resistance coefficient and viscous resistance coefficient. The specific value of the resistance coefficient shows that the target porosity of the target building unit can be used as a preset parameter to determine the preset inertial resistance coefficient and preset viscous resistance coefficient of the porous media unit.

On the basis of the above-mentioned embodiments, the method for determining the preset parameters in the CFD numerical simulation-based building wind environment assessment method provided in the embodiments of the present invention also includes:

Based on the preset software, construct a three-dimensional model of multiple second-type sample porous media units with the same porosity and different morphological parameters, so as to simulate sample building units with different morphological parameters, and determine the calculation domain and boundary conditions;

Based on the three-dimensional models of the plurality of second-type sample porous media units, the calculation domain and the boundary conditions, respectively calculate the flow field and pressure drop of each second-type sample porous media unit;

According to the flow field and pressure drop of each second-type sample porous media unit, respectively determine the quantitative relationship between the flow field and pressure drop of each second-type sample porous media unit, and respectively determine the porous media unit of each second-type sample The inertial resistance coefficient and viscous resistance coefficient of the medium unit;

If the inertial resistance coefficients of each second-type sample porous media unit are different, and the viscous resistance coefficients of each second-type sample porous media unit are different, then the morphological parameters of the porous media unit are used as the predetermined Set parameters.

Specifically, S31, in SpaceClaim19.0 software, the three-dimensional modeling of the building unit is carried out, and two porous media units of a cube and a cuboid (that is, the second type of sample porous media unit) are respectively constructed to simulate the cube sample building unit and Cuboid sample building unit. And two three-dimensional models are correspondingly obtained, and each porous medium unit of the second type sample is a window opening mode with a porosity of 10%.

S32, establish the calculation domain, the two 3D models correspond to the two calculation domains, the calculation domain is as large as the outer frame of the windward side (ie longitudinal section) of the corresponding second type sample porous media unit, and the front and rear depths are respectively extended by 3-5 times The spatial distance from the side length of the porous media unit of the second type of sample. Note that the calculation domain whose longitudinal section is larger than the porous media unit of the second type sample cannot be done here, because when calculating the inlet wind speed and pressure drop of the porous media unit of the second type sample, the two sides of the porous media unit of the second type sample and the The space above is added, otherwise it will affect the result.

S33-S36 are exactly the same as above-mentioned S23-S26.

The flow field and pressure field curves of the porous media unit of the second type of sample are calculated and drawn as a flow field and pressure field curve, as shown in Figure 4, where Figure 4(a) is the second type of cuboid sample with a porosity of 10%. The flow field pressure field curve of the porous medium unit, the quadratic coefficient of the curve is k ₁ =83.767, the first power coefficient is k ₂ =3.1136, the thickness of the second type of porous medium used is 9.49m, and the air density is 1.225kg /m ³ , according to formula (8), the inertial resistance coefficient C ₂ is 14.4112, and the viscous resistance coefficient 1/α is 18335.3. Figure 4(b) shows the flow field and pressure field curve of the cube second sample porous medium unit with a porosity of 10%. The quadratic coefficient is k ₁ =89.148, and the first power coefficient is k ₂ =3.7195. The second The thickness of the sample-like porous medium is 9.49m, and the air density is 1.225kg/m ³ . According to formula (8), the inertial resistance coefficient C ₂ is 15.3369, and the viscous resistance coefficient 1/α is 19481.2.

From the results of the inertial resistance coefficient and viscous resistance coefficient obtained above, it can be known that the difference between the inertial resistance coefficient and viscous resistance coefficient of each second type sample porous media unit is not large, and the relative error Δ/L is -1 times of 10 Within the order of magnitude, they can be considered equal within the allowable range of error. It means that the morphological parameters of the target building unit will not affect the specific values of the inertial resistance coefficient and viscous resistance coefficient, and the morphological parameters of the target building unit cannot be used as preset parameters to determine the preset inertial resistance coefficient and the preset inertial resistance coefficient of the porous media unit. Set the viscous drag coefficient.

On the basis of the above-mentioned embodiments, the method for determining the building wind environment assessment method based on CFD numerical simulation provided in the embodiments of the present invention also includes:

Based on the preset software, respectively construct the window model of the sample building unit and the wall model of the third type of sample porous media unit, and determine the calculation domain and boundary conditions;

Changing the wind environment parameters of the fenestration model and the wall model, and determining the wind environment parameters in different wind environments based on the fenestration model, the wall model, the calculation domain and the boundary conditions The first type of flow field distribution obtained by the fenestration model model described below, and the second type of flow field distribution obtained by the wall model;

If the distribution of the first type of flow field is inconsistent with the distribution of the second type of flow field, the wind environment parameter is used as the preset parameter.

Specifically, in the embodiment of the present invention, two sample building units with the same 10% porosity and two sample porous media units of the third type are used as examples for illustration, and each sample porous media unit of the third type is used to simulate a sample Single building. The two sample building units are respectively a cube with windows and a cuboid with windows, and they are distributed diagonally. distributed. In the embodiment of the present invention, it is necessary to perform fluid dynamics simulation on the third type of sample porous media unit under wind environments with different wind directions and wind speeds, which includes at least four working conditions: straight wind direction, wind direction turning 135°, and wind speed 2m/s (2 Level wind) and wind speed 4m/s (3-level wind), the comparison between the window opening mode and the wall entity of the porous media unit under different wind environments is obtained, and the corresponding flow field and pressure field are obtained.

Taking the wind direction direct entry as an example, the flow field and pressure field of the wind direction direct entry window opening mode and the flow field and pressure field of the wall entity of the porous medium unit are obtained.

Specifically, S41, in SpaceClaim19.0 software, the three-dimensional modeling of building monomers is carried out, and the window model models of sample building monomers distributed diagonally in cubes and cuboids and the walls of the third type of sample porous media units are respectively constructed Model with a porosity of 10%.

S42, establish the calculation domain, reserve enough calculation domain on the outer frame of the windward side of the sample building unit and the third type sample porous media unit, the side length of the calculation domain is 3-5 of the sample building unit and the third type sample porous media unit times to ensure turbulent flow for fully developed flow.

S43. Determine the boundary and the minimum grid unit. Import the window mode model, wall model and computational domain into ICEMCFD19.0. Considering the change of wind direction, two air inlets (INLET) need to be set, and similarly, two air outlets (OUTLET) are required. What needs to be explained here is that in the embodiment of the present invention, when the wind direction is horizontal at 0°, the wind direction is perpendicular to the windward side. At this time, the air inlet ① and the air outlet ①' are selected, and 1 atmospheric pressure is set on the windward side at the boundary of the air outlet ①' Reference. When the wind direction is inclined at 45°, the setting is different from when the wind direction is horizontal at 0°. The wind direction and the normal line of the windward surface form an included angle, and the air inlet ② and the air outlet ②’ are selected. When the wind environment parameters change, set two air inlets and an air outlet corresponding to each air inlet at the same time, that is, when the wind direction changes, the air inlets are set to ① and ②, and the air outlets are set to ①' and ②', The rest of the faces are set as solid walls. Set the minimum mesh size (Part Mesh) according to the window size of the window model model divided by 5, and set the maximum value (Max element) of the global mesh (Global Mesh) to "0.002".

S44, setting a grid type and a grid generation method. The grid type is "Quad Dominant", and the grid calculation method is "Patch Dependent". Execute the generate grid command to generate 2 million grids.

S45, setting boundary conditions. Import the generated grid into FLUENT, set the wind speed of the wind environment to 4 m/s, the wind speed in the upper and lower spaces is the same, and the initial wind direction is parallel to the normal of the windward side. At the leeward side of the third type of sample porous media unit (that is, the wind outlet boundary), and at the leeward side of the sample building unit (that is, the wind outlet boundary), the wind pressure is set to a reference value of 1 atmospheric pressure; the turbulence model is "k -epsilon" mode; the surfaces of the window model and the wall model are set to no-slip boundaries, and the material is set to "solid".

When the angle between the initial wind direction and the normal line of the windward side is 135° and the wind speed is 4m/s, other conditions remain unchanged.

S46, the solver initializes and calculates. After the parameters are set, the first type of flow field distribution obtained by the window model model and the second type of flow field distribution obtained by the wall model under different wind environment parameters are calculated. As shown in Figure 5, among them, Figure 5(a) is the contour map of the first type of flow field distribution when the wind direction is parallel to the normal line of the windward surface and the wind speed is 2m/s, and Figure 5(b) is the contour diagram of the wind direction and the windward surface The contour map of the second type of flow field distribution when the normals are parallel and the wind speed is 2m/s. Comparing Figure 5(a) with Figure 5(b), it can be seen that when the wind direction is parallel to the normal of the windward surface and the wind speed is 2m/s, the distribution of the first type of flow field is consistent with the distribution of the second type of flow field. Figure 5(c) is the contour map of the first type of flow field distribution when the angle between the wind direction and the normal line of the windward side is 135° and the wind speed is 4m/s, and Figure 5(d) is the angle between the wind direction and the normal line of the windward side The contour map of the second type of flow field distribution when the angle is 135° and the wind speed is 4m/s. Comparing Figure 5(c) with Figure 5(d), it can be seen that when the angle between the wind direction and the normal line of the windward surface is 135° and the wind speed is 4m/s, the distribution of the first type of flow field and the distribution of the second type of flow field The situation is also consistent, which means that the wind environment parameters cannot be used as preset parameters, that is, the wind environment of the target building unit will not affect the specific values of the inertial resistance coefficient and viscous resistance coefficient, indicating that the target building unit is located The wind environment parameters of the wind environment cannot be used as preset parameters to determine the preset inertial resistance coefficient and preset viscous resistance coefficient of the porous media unit.

What needs to be explained here is that when comparing the flow field distribution, there will be a certain error in the velocity value of the same spatial position in the two flow field distributions, and the flow field distribution can be considered to be consistent within the allowable range of the error. In general, this relative error needs to be controlled in the order of 0.1.

On the basis of the above-mentioned embodiments, in the CFD numerical simulation-based building wind environment assessment method provided in the embodiments of the present invention, the determination method further includes:

Based on the preset software, construct wall models of multiple fourth-type sample porous media units with different porosities, and window model models of sample building units with different porosities, and determine the calculation domain and boundary conditions;

changing the wind environment parameters in which the multiple wall models and the windowing pattern models are located, and determining multiple The wall surface models correspond to the third type of flow field distribution of any layout parameter in the calculation domain under the same wind environment parameters, and respectively determine that a plurality of the fenestration model models correspond to the above described wind environment parameters under the same wind environment parameters Computing the fourth type of flow field distribution for said arbitrary layout parameters in the domain;

If the distribution of the third type of flow field is inconsistent with the distribution of the fourth type of flow field, the layout parameters of the plurality of wall models in the calculation domain are used as the preset parameters.

Specifically, the function of the embodiment of the present invention is to determine whether the layout parameters of the target building unit in the corresponding calculation domain can be used as preset parameters.

Taking the sample building units with 10%, 20%, and 30% porosity as examples, the windowed cubes and windowed cuboids are studied under any wind direction and wind speed in any layout, and the wall cubes and The wall cuboid of the fourth type of sample porous media unit is studied under the same layout as the windowed cube and the windowed cuboid and the same wind direction and wind speed. This requires fluid dynamics simulation of the above model in the case of arbitrary layout and wind environment changes, including at least four working conditions: wind direction 0°, wind direction 45°, wind speed 2m/s, wind speed 4m/s, different Arbitrary layout of the sample building unit combination with porosity, arbitrary layout of the fourth type of sample porous media unit combination with different porosity, a total of 2×2 comparison conditions, the window model model and the fourth type of sample porous media unit are obtained The wall model is compared in different block shapes and external environment changes, and the detection indicators adopt flow field, pressure field and sample point to collect data.

Under the conditions of wind direction 0° and wind speed 2m/s, the flow field and pressure field of random layout of the window model model of the sample building with 10%, 20% and 30% porosity, and the collection of wind direction 0° and wind speed 2m Under the condition of 10%, 20%, and 30% porosity, the wall model of the fourth type of sample porous media unit has the same layout as the window model model, and the flow field and pressure field can also be collected from some sample points for quantitative analysis. examine. The implementation steps are as follows:

S51, in the SpaceClaim19.0 software, three-dimensional modeling of the building unit is carried out, and the window model models of the three sample building units with any layout and the wall model of the fourth type of sample porous media unit with the same layout are respectively constructed. The porosity in the layout is 10%, 20% and 30%, respectively. It should be noted here that each layout corresponds to a layout parameter, and the layout parameter is used to represent the layout.

S52, establish the calculation domain, leave enough calculation domain on the outer frame of the windward side of the sample building unit and the fourth type sample porous media unit, the side length of the calculation domain is 3-5 of the sample building unit and the fourth type sample porous media unit times to ensure turbulent flow for fully developed flow.

S53, determine the boundary and the minimum grid unit, and import the wall model, window pattern model and calculation domain into ICEMCFD19.0. Considering the change of wind direction, two air inlets (INLET) need to be set, and similarly, two air outlets (OUTLET) are required. What needs to be explained here is that in the embodiment of the present invention, when the wind direction is horizontal at 0°, the wind direction is perpendicular to the windward side. At this time, the air inlet ① and the air outlet ①' are selected, and 1 atmospheric pressure is set on the windward side at the boundary of the air outlet ①' Reference. When the wind direction is inclined at 45°, the setting is different from when the wind direction is horizontal at 0°. The wind direction and the normal line of the windward surface form an included angle, and the air inlet ② and the air outlet ②’ are selected. When the wind environment parameters change, set two air inlets and an air outlet corresponding to each air inlet at the same time, that is, when the wind direction changes, the air inlets are set to ① and ②, and the air outlets are set to ①' and ②', The rest of the faces are set as solid walls. Set the minimum mesh size (Part Mesh) according to the window size of the window model model divided by 5, and set the maximum value (Max element) of the global mesh (Global Mesh) to "0.002".

S54, setting a grid type and a grid generation method. The grid type is "Quad Dominant", and the grid calculation method is "Patch Dependent". Execute the generate grid command to generate 2 million grids.

S55, setting boundary conditions. Import the generated grid into FLUENT, set the wind speed of the wind environment to 2 m/s, the wind speed in the upper and lower spaces is the same, and the initial wind direction is parallel to the normal of the windward side. At the leeward side of the porous media unit of the fourth type sample (that is, the outlet boundary of the wind), and at the leeward surface of the sample building unit (that is, the outlet boundary of the wind), the wind pressure is set to a reference value of 1 atmospheric pressure; the turbulence model is "k -epsilon" mode; the surfaces of the window model and the wall model are set to no-slip boundaries, and the material is set to "solid".

When the angle between the initial wind direction and the normal line of the windward side is 45° and the wind speed is 4m/s, other conditions remain unchanged.

S56, the solver initializes and calculates. After the parameters are set, calculate the third type of flow field distribution of the three wall models corresponding to any layout parameters in the calculation domain under the same wind environment parameters, and respectively determine the corresponding flow field distributions of a plurality of the fenestration model models under the same wind environment parameters The fourth type of flow field distribution of arbitrary layout parameters in the computational domain. As shown in Figure 6, among them, Figure 6(a) is the contour map of the third type of flow field distribution when the wind direction is parallel to the normal line of the windward surface and the wind speed is 2 m/s, and Figure 6(b) is the contour map of the wind direction and the windward surface The contour map of the fourth type of flow field distribution when the normal line is parallel and the wind speed is 2 m/s. Comparing Figure 6(a) with Figure 6(b), it can be seen that when the wind direction is parallel to the normal of the windward surface and the wind speed is 2 m/s, the distribution of the third type of flow field is consistent with the distribution of the fourth type of flow field. Figure 6(c) is the contour map of the third type of flow field distribution when the angle between the wind direction and the normal line of the windward side is 45° and the wind speed is 4m/s, and Figure 6(d) is the angle between the wind direction and the normal line of the windward side The contour map of the fourth type of flow field distribution at 45° and wind speed of 4m/s. Comparing Figure 6(c) with Figure 6(d), it can be seen that when the angle between the wind direction and the normal line of the windward surface is 45° and the wind speed is 4m/s, the distribution of the third type of flow field and the distribution of the fourth type of flow field If the situation is also consistent, it means that the layout parameters of the target building unit in the corresponding calculation domain cannot be used as preset parameters, that is, the layout parameters of the target building unit in the corresponding calculation domain will not affect the specific parameters of the inertial resistance coefficient and viscous resistance coefficient. value, indicating that the layout parameters of the target building unit in the corresponding calculation domain cannot be used as preset parameters to determine the preset inertial resistance coefficient and preset viscous resistance coefficient of the porous media unit.

The purpose of the embodiments of the present invention is to provide a building wind environment assessment method using fluid mechanics to simulate a "porous medium unit" that conforms to real buildings with natural draft or artificial ventilation effects. In addition, it has a preset inertial resistance coefficient and preset viscosity. The porous media unit of the resistance coefficient is suitable for simulating urban buildings with any shape and layout, any wind inlet angle and wind speed, and the preset inertial resistance coefficient and preset viscous resistance coefficient are only related to the porosity of the building monomer and the porous media unit It is related to the thickness and flow resistance characteristics of porous media. The wind environment assessment method proposed in the embodiment of the present invention is used to simulate the ventilation conditions of urban buildings, and the calculation amount is greatly reduced compared with the simulation of indoor window opening three-dimensional solid modeling.

The embodiment of the invention discloses a building wind environment assessment method considering the effect of building body flow, which belongs to the technical field of fluid dynamics numerical simulation of building wind environment. The problem of dynamic air circulation around the diversity of building monomer shapes solves the dilemma that the "draft" or "artificial ventilation" effect of high-density buildings cannot be reflected in numerical simulations. The accuracy of building single simulation is of positive significance. The key technical point of the present invention is: taking into account the drag force between the gas-solid two-phase flow inside the building unit, the embodiment of the present invention proposes a processing method for simulating the building unit by using a porous medium unit. Added to the standard fluid equation to reflect, using the volume average technology, k-ε turbulence simulation technology to establish the mathematical equations of the porous media unit suitable for the turbulent flow between urban buildings, and use the micro-scale numerical simulation to calculate the space of the results The validity of the model was verified by volume averaging. In the embodiment of the present invention, the method of CFD numerical simulation is used to quantitatively describe the relationship between wind speed, pressure drop and the porosity of the building monomer, and to determine the condition that the porous medium unit can simulate the building monomer, and the wind environment, building The shape of the monomer and the layout in the computational domain are irrelevant, but only related to the porosity of the building monomer, the thickness of the porous medium unit, and the flow resistance characteristics of the porous medium. The method proposed in the embodiment of the present invention greatly reduces the calculation amount of 3D simulation of occlusions in real scenes, and is expected to advance the general building and block scale (<1km) calculated by high-precision CFD numerical simulation to the urban scale (<10km) , providing scientific evidence for urban planners and government decision-making to build resource-sustainable cities.

As shown in FIG. 7 , on the basis of the above embodiments, the embodiment of the present invention also provides a building wind environment assessment system based on CFD numerical simulation, including: a wind environment assessment module 71 . in,

The wind environment assessment module 71 is used to perform computational fluid dynamics CFD numerical simulation on the target building unit based on the porous media unit, determine the wind speed in the calculation domain and the pressure drop between the air inlet and the air outlet in the calculation domain, so as to evaluate the The flow field and pressure drop around the target building monomer; the porous media unit has a preset inertial resistance coefficient and a preset viscous resistance coefficient; wherein, when performing the CFD numerical simulation, a porous media unit model is established and determined the governing equation and the source term of the momentum equation of the porous media unit model in the calculation domain; based on the governing equation and the source term of the momentum equation, determine the flow field and pressure drop around the porous media unit model, and The determined flow field and pressure drop around the porous medium unit model are used as the flow field and pressure drop around the target building unit.

Specifically, the functions, processing flow and technical effects of each module in a building wind environment assessment system based on CFD numerical simulation provided in the embodiments of the present invention correspond one-to-one with the above-mentioned method embodiments, and the implementation of the present invention The examples will not be repeated here.

On the basis of the above-mentioned embodiments, an embodiment of the present invention also provides a building wind environment assessment device based on CFD numerical simulation, including:

at least one processor; and

at least one memory communicatively coupled to the processor, wherein:

The memory stores program instructions executable by the processor, and the processor calls the program instructions to execute the method as described in FIG. 1 .

On the basis of the above-mentioned embodiments, an embodiment of the present invention also provides a non-transitory computer-readable storage medium, the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute The method described in Figure 1.

The device embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in One place, or it can be distributed to multiple network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without any creative efforts.

Through the above description of the implementations, those skilled in the art can clearly understand that each implementation can be implemented by means of software plus a necessary general hardware platform, and of course also by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the prior art can be embodied in the form of software products, and the computer software products can be stored in computer-readable storage media, such as ROM/RAM, magnetic discs, optical discs, etc., including several instructions to make a computer device (which may be a personal computer, server, or network device, etc.) execute the methods described in various embodiments or some parts of the embodiments.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (10)

1. A building wind environment assessment method considering building flow-through effect based on CFD is characterized by comprising the following steps:

based on a porous medium unit, performing Computational Fluid Dynamics (CFD) numerical simulation on a target building monomer with target porosity, and determining the wind speed of a calculation domain and the pressure drop between an air inlet and an air outlet of the calculation domain so as to evaluate the flow field and the pressure drop around the target building monomer; the porous medium unit has a preset inertial resistance coefficient and a preset viscous resistance coefficient;

establishing a porous medium unit model during the CFD numerical simulation, and determining a control equation and a momentum equation source term of the porous medium unit model in the calculation domain;

and determining the flow field and the pressure drop around the porous medium unit model based on the control equation and the source term of the momentum equation, and taking the determined flow field and the determined pressure drop around the porous medium unit model as the flow field and the pressure drop around the target building monomer.

2. The CFD-based building wind environment assessment method considering building flow-through effect according to claim1, wherein said source terms of momentum equation are represented by the following formula:

wherein S is_iIs the source term of the ith dimension momentum equation, mu is a constant, p is the fluid density, | v | represents the absolute value of the fluid velocity, v |, v_irepresenting the ith dimension velocity of the fluid, 1/α being the preset viscous drag coefficient, C₂Is the preset inertial resistance coefficient, i ═ x, y, or z.

3. The CFD-based building wind environment assessment method considering building body flow-through effect according to claim1, wherein said preset inertial resistance coefficient and said preset viscous resistance coefficient are determined according to preset parameters, said preset parameters being determined based on preset software.

4. The CFD-based building wind environment assessment method considering the building flow-through effect according to claim 3, wherein said preset parameters are determined by the following determination method:

constructing a three-dimensional model of a plurality of first-class sample porous medium units with the same form and different porosities based on the preset software to simulate sample building monomers with different porosities, and determining the calculation domain and the boundary condition;

respectively calculating the flow field and the pressure drop of each first type sample porous medium unit based on the three-dimensional models of the plurality of first type sample porous medium units, the calculation domain and the boundary condition;

respectively determining the quantitative relation between the flow field and the pressure drop of each first type sample porous medium unit according to the flow field and the pressure drop of each first type sample porous medium unit, and respectively determining the inertial resistance coefficient and the viscous resistance coefficient of each first type sample porous medium unit;

and if the inertia resistance coefficients of the first type sample porous medium units are different and the viscosity resistance coefficients of the first type sample porous medium units are different, taking the target porosity of the target building monomer as the preset parameter.

5. The CFD-based building wind environment assessment method considering building flow-through effect according to claim 4, wherein said determination method further comprises:

based on the preset software, constructing a three-dimensional model of a plurality of second type sample porous medium units with the same porosity and different morphological parameters to simulate sample building monomers with different morphological parameters, and determining the calculation domain and the boundary condition;

respectively calculating the flow field and the pressure drop of each second type sample porous medium unit based on the three-dimensional models of the second type sample porous medium units, the calculation domains and the boundary conditions;

respectively determining the quantitative relation between the flow field and the pressure drop of each second type sample porous medium unit according to the flow field and the pressure drop of each second type sample porous medium unit, and respectively determining the inertial resistance coefficient and the viscous resistance coefficient of each second type sample porous medium unit;

and if the inertia resistance coefficients of the second type sample porous medium units are different and the viscosity resistance coefficients of the second type sample porous medium units are different, taking the morphological parameters of the target building monomer as the preset parameters.

6. The CFD-based building wind environment assessment method considering building flow-through effect according to claim 4, wherein said determination method further comprises:

respectively constructing a windowing mode model of a sample building monomer and a wall model of a third type of sample porous medium unit based on the preset software, and determining the calculation domain and the boundary condition;

changing the wind environment parameters of the windowing mode model and the wall surface model, and respectively determining the first type of flow field distribution obtained by the windowing mode model under different wind environment parameters and the second type of flow field distribution obtained by the wall surface model based on the windowing mode model, the wall surface model, the calculation domain and the boundary condition;

and if the distribution situation of the first type of flow field is inconsistent with the distribution situation of the second type of flow field, taking the wind environment parameter as the preset parameter.

7. The CFD-based building wind environment assessment method considering building flow-through effect according to claim 4, wherein said determination method further comprises:

respectively constructing wall surface models of a plurality of fourth type sample porous medium units with different porosities and windowing mode models of sample building monomers with different porosities based on the preset software, and determining the calculation domain and the boundary condition;

changing wind environment parameters of the plurality of wall models and the windowing mode models, respectively determining a third type of flow field distribution of the plurality of wall models corresponding to any layout parameter in the calculation domain under the same wind environment parameters and a fourth type of flow field distribution of the plurality of windowing mode models corresponding to any layout parameter in the calculation domain under the same wind environment parameters based on the plurality of wall models, the windowing mode models, the calculation domain and the boundary conditions;

and if the distribution situation of the third type of flow field is inconsistent with that of the fourth type of flow field, taking the layout parameter of the target building monomer in the corresponding calculation domain as the preset parameter.

8. The CFD-based building wind environment assessment method considering building flow-through effect according to claim 6 or 7, wherein when the wind environment parameter changes, two air inlets and the air outlet corresponding to each air inlet are provided at the same time.

9. The CFD-based building wind environment assessment method considering building flow-through effect according to any one of claims 2-7, wherein said preset software comprises: ANSYS FLUENT, the provisioning software further comprising: SpaceMehaim, NX (UG), AutoCAD or SketchUp pro, the preset software further comprises: ANSYS discover live.

10. A building wind environment assessment system considering building flow-through effect based on CFD is characterized by comprising:

the wind environment evaluation module is used for carrying out Computational Fluid Dynamics (CFD) numerical simulation on a target building monomer based on the porous medium unit, and determining the wind speed of a calculation domain and the pressure drop between an air inlet and an air outlet of the calculation domain so as to evaluate the flow field and the pressure drop around the target building monomer; the porous medium unit has a preset inertial resistance coefficient and a preset viscous resistance coefficient;

establishing a porous medium unit model during the CFD numerical simulation, and determining a control equation and a momentum equation source term of the porous medium unit model in the calculation domain;

and determining the flow field and the pressure drop around the porous medium unit model based on the control equation and the source term of the momentum equation, and taking the determined flow field and the determined pressure drop around the porous medium unit model as the flow field and the pressure drop around the target building monomer.