CN109033664A

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

Info

Publication number: CN109033664A
Application number: CN201810890672.2A
Authority: CN
Inventors: 刘芳; 位帅帅; 周命端; 苏毅; 魏菲宇; 周俊
Original assignee: Beijing University of Civil Engineering and Architecture
Current assignee: Beijing Zhongrun Hantai Technology Co ltd
Priority date: 2018-08-07
Filing date: 2018-08-07
Publication date: 2018-12-18
Anticipated expiration: 2038-08-07
Also published as: CN109033664B

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

CFD-based building wind environment assessment method considering building flow-through effect

Technical Field

The embodiment of the invention relates to the technical field of wind environments of hydromechanics buildings, in particular to a CFD-based building wind environment assessment method considering the flow-through effect of a building.

Background

With the development of society and the acceleration of urbanization process, the air circulation condition of buildings and the change of wind environment caused by the buildings need to be considered in the building process of high-rise buildings in cities. The narrow wind channel forms a tunnel effect, so that the wind speed in the area is obviously accelerated, thereby causing the problems of insecurity and discomfort of pedestrians in the walking and moving processes.

At present, the research work on the dynamic diffusion mechanism of the building is usually carried out by adopting two modes of wind tunnel simulation test and computer numerical simulation wind environment. The wind tunnel simulation test (wind-tunnel testing) refers to an aerodynamic experiment simulation method for placing an aircraft or other object model in a wind tunnel, and researching gas flow and interaction between the gas flow and the model to know aerodynamic characteristics of the actual aircraft or other objects. The computer numerical simulation wind environment is mainly simulated by using Computational Fluid Dynamics (CFD) numerical simulation, and compared with a wind tunnel simulation test, the CFD numerical simulation has the advantages of low cost, short time consumption, easiness in obtaining abundant flow field result information, easiness in carrying out sensitivity analysis on parameter change and easiness in realizing simulation of a complicated real flow condition. There has been a great deal of work in building wind environment simulation.

However, although the wind tunnel simulation test can accurately deduce the wind environment of the building, the environment scale required by the test is large, and the instrument is expensive, so the wind tunnel simulation test is not suitable for testing the simulation requirements under different environment parameters. Although the CFD numerical simulation has the advantages that wind tunnel simulation tests do not have, the reliability of the method adopting the CFD numerical simulation needs to be verified through later experiments due to the limitation of the turbulence theory itself, the adaptation range of the turbulence model and the adaptability of the calculation method, and the complexity is increased. Moreover, determining an appropriate turbulence model for each different building is required, which greatly increases the amount of computation.

Disclosure of Invention

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

In one aspect, an embodiment of the present invention provides a building wind environment assessment method considering a building flow-through effect based on CFD numerical simulation, including:

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.

On the other hand, the embodiment of the invention provides a building wind environment evaluation system considering a building flow-through effect based on CFD numerical simulation, which comprises the following steps:

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; measuring and calculating the preset inertial resistance coefficient and the preset viscous resistance coefficient of the porous medium unit when the porous medium unit represents a building monomer;

According to the CFD-based building wind environment assessment method considering the building body flow-through effect, the porous medium unit is adopted to simulate the target building single body, the window-opening mode of the constructed target building single body model is not required to be researched, and the target building single body is researched by taking the multiple holes of the porous medium unit as windows. The method has positive significance for constructing the air-permeable building single body and improving the simulation precision of the urban building single body. Compared with the three-dimensional simulation calculation amount of the real-scene indoor shelter, the method provided by the embodiment of the invention is greatly reduced, and is expected to push the general building and block scale (<1km) of high-precision CFD numerical simulation calculation to the urban scale (<10km), thereby providing scientific evidence for city planning designers and governments to decide and construct sustainable cities of resources. The problem of the dynamic diffusion of atmospheric particles due to the layout and the form (the form of a single building, a building group and a street outline) of the urban underlying surface is solved, and a scientific basis is provided for urban atmospheric environment planning and design.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

Fig. 1 is a schematic flow chart of a building wind environment assessment method considering a building flow-through effect based on CFD according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a computational domain of a CFD-based building wind environment assessment method considering a building flow-through effect according to an embodiment of the present invention;

fig. 3(a) is a flow field pressure field graph of a first type of sample porous medium unit with a porosity of 10% in a CFD-based method for evaluating a building wind environment considering a building flow-through effect according to an embodiment of the present invention; fig. 3(b) is a flow field pressure field graph of a first type of sample porous medium unit with a porosity of 20% in a CFD-based method for evaluating a building wind environment considering a building flow-through effect according to an embodiment of the present invention; fig. 3(c) is a flow field pressure field graph of a first type of sample porous medium unit with a porosity of 30% in a CFD-based method for evaluating a building wind environment considering a building flow-through effect according to an embodiment of the present invention;

fig. 4(a) is a schematic view of a flow field and a pressure field curve of a cuboid second type sample porous medium unit in a building wind environment assessment method considering a building flow-through effect based on CFD according to an embodiment of the present invention; fig. 4(b) is a schematic view of a flow field and pressure field curve of a cubic second type sample porous medium unit;

fig. 5(a) is a contour map of a first type of flow field distribution when a wind direction is parallel to a normal of a windward surface and a wind speed is 2m/s in a building wind environment assessment method considering a building body percolation effect based on CFD provided by an embodiment of the present invention, fig. 5(b) is a contour map of a second type of flow field distribution when the wind direction is parallel to the normal of the windward surface and the wind speed is 2m/s in a building wind environment assessment method considering the building body percolation effect based on CFD provided by an embodiment of the present invention, fig. 5(c) is a contour map of a first type of flow field distribution when an included angle between the wind direction and the normal of the windward surface is 135 degrees and the wind speed is 4m/s in a building wind environment assessment method considering the building body percolation effect based on CFD provided by an embodiment of the present invention, and fig. 5(d) is a building wind environment assessment method considering the building body percolation effect based on CFD provided by an embodiment of the present invention, The contour map of the second type of flow field distribution when the wind speed is 4 m/s;

fig. 6(a) is a contour map of a third type of flow field distribution when a wind direction is parallel to a normal line of a windward surface and a wind speed is 2m/s in a building wind environment assessment method considering a building body percolation effect based on CFD provided by an embodiment of the present invention, fig. 6(b) is a contour map of a fourth type of flow field distribution when a wind direction is parallel to a normal line of a windward surface and a wind speed is 2m/s in a building wind environment assessment method considering a building body percolation effect based on CFD provided by an embodiment of the present invention, fig. 6(c) is a contour map of a third type of flow field distribution when an included angle between a wind direction and a normal line of a windward surface is 45 ° and a wind speed is 4m/s in a building wind environment assessment method considering a building body percolation effect based on CFD provided by an embodiment of the present invention, and fig. 6(d) is a building wind environment assessment method considering a building body percolation effect based on CFD provided by an embodiment of the present invention, in which an included angle between a wind direction and a normal line and a windward surface is 45 °, The contour map of the fourth type of flow field distribution when the wind speed is 4 m/s;

fig. 7 is a schematic structural diagram of a building wind environment evaluation system considering a building flow-through effect based on CFD according to an embodiment of the present invention.

Detailed Description

In order to make the objects, 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 with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, an embodiment of the present invention provides a method for evaluating a building wind environment based on CFD numerical simulation and considering a building flow-through effect, including:

s1, performing Computational Fluid Dynamics (CFD) numerical simulation on a target building single body with target porosity based on a 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 single body; the porous medium unit has a preset inertial resistance coefficient and a preset viscous resistance coefficient;

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

In the simulation of the target building units using the porous medium units, the porous medium units having a predetermined inertial resistance coefficient and a predetermined viscous resistance coefficient are required to have a specific target porosity for each target building unit. That is, the values of the preset inertial resistance coefficient and the preset viscous resistance coefficient have a direct corresponding relationship with the target porosity.

Here, the calculation domain is a size of a region to be studied in performing the CFD numerical simulation, and is generally a region that is as large as an outer frame (i.e., a vertical section) of the porous medium unit facing the wind, and is formed by extending a spatial distance 3 to 5 times as large as a side length of the porous medium unit in each of the forward and backward depths, and the porous medium unit is disposed in the calculation domain.

In the embodiment of the invention, the porous medium unit is adopted to simulate the target building single body, and the target building single body is researched by taking the multiple holes of the porous medium unit as windows without researching a windowing mode of the constructed target building single body model. The method has positive significance for constructing the air-permeable building single body and improving the simulation precision of the urban building single body. Compared with the three-dimensional simulation calculation amount of the real-scene indoor shelter, the method provided by the embodiment of the invention is greatly reduced, and is expected to push the general building and block scale (<1km) of high-precision CFD numerical simulation calculation to the urban scale (<10km), thereby providing scientific evidence for city planning designers and governments to decide and construct sustainable cities of resources. The problem of the dynamic diffusion of atmospheric particles due to the layout and the form (the form of a single building, a building group and a street outline) of the urban underlying surface is solved, and a scientific basis is provided for urban atmospheric environment planning and design.

On the basis of the above embodiment, the porous medium unit model established in the embodiment of the present invention includes a physical model and a mathematical model, which are specifically as follows:

when the object of interest is a porous media element, the flow resistance per unit area of fluid passing through the porous media element is considered to be constant and uniform. The method is realized by adding a source term in a momentum equation in a mathematical model of the porous medium unit, and the mathematical model of the porous medium unit suitable for urban turbulent flow and heat exchange is established by adopting a volume average technology and a Reynolds time-average equation method in the embodiment of the invention. Determining the fluid velocity before passing through the porous medium unit, the pressure on the wall surface (windward side) of the porous medium unit and the pressure on the wall surface (leeward side) of the porous medium unit after passing through the porous medium unit, and determining the physical characteristics of the porous medium unit model according to a method of flow velocity before an inlet hole and pressure drop after the inlet hole, wherein the quantitative relation between the flow velocity and the pressure drop is different according to the pore morphology and the porosity of the porous medium unit. The control equation in the embodiment of the invention refers to a continuity equation of fluid flow, a momentum equation of a porous medium unit model, an energy equation of the porous medium unit model and the like.

The continuity equation for fluid flow is:

wherein gamma is the porosity of the porous medium, rho_qis the q-phase fluid phase density, α_qIs the volume fraction of the q-phase,is a q-phase velocity vector and,the mass transfer is characterized from the p phase to the q phase,characterisation of mass transfer from q-phase to p-phase, S_qIs the source term of momentum resistance.

Momentum equation for porous media element model:

wherein, mu_qIs q-phase shear force, λ_qIs a q-phase viscosity coefficient of the copolymer,the external volume force to which the porous media element is subjected under q-phase conditions,the lifting force to which the porous medium unit is subjected under the q-phase condition,the wall surface lubricating force of the porous medium unit under the q-phase condition,is the virtual mass force to which the porous medium unit is subjected under the q-phase condition,is the turbulent dispersion force (not 0 in the case of turbulent flow only, but 0 in all other cases) to which the porous media element is subjected under q-phase conditions. P is the pressure of interaction between the P and q phases.Represents the transmission speed between the p and q phases, ifGreater than zero, characterizing mass transfer from p-phase to q-phase, thenIf it is notLess than zero, characterizing mass transfer from q-phase to p-phase, thenIs a p, q phaseThe interaction force between them, depending on friction, pressure, cohesion and other effects, and influenced by conditions,is the compressive strain tensor of the q-phase, C_2,qIs the inertial resistance coefficient, K, of the q-phase porous medium unit_qIs the solid phase thermal conductivity coefficient.

The last term in the formula (2) is a momentum resistance source term in the porous medium unit and consists of two parts of a viscous loss term and an inertial loss term.

And simulating the standard energy transportation process of the porous medium unit by adopting an equilibrium thermal model equation, namely setting the porous medium unit and the fluid flow to be in a thermal equilibrium state. Where the conduction flux uses the effective conductivity, the transient term includes the thermal inertia of the solid region on the medium. The energy equation of the porous medium cell model is shown in formula (3):

wherein gamma is the porosity of the fluid-solid two-phase medium; q_spIs 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_qh_q，eff(T_s-T_q) (4)

wherein h is_q，effEffective convective heat transfer coefficient for q-phase, T_sIs the solid surface temperature, T, in the porous media element_qIs the temperature of the q-phase fluid.

From the formula (3) and the formula (4), the expression of the momentum resistance source term adopted by the simulation porous medium unit is shown as the formula (5).

Wherein S is_iIs the source item of the ith-dimension momentum equation and consists of two parts: a viscous loss term (i.e., the first term on the right of the equal sign in equation (5)) and an inertial loss term (i.e., the second term on the right of the equal sign in equation (5)). | v | represents the absolute value of the fluid velocity, ρ is the density of the fluid, μ is a constant value, and is 1.7894 × 10^-5. The value of i is x, y and z, and each dimension in the three-dimensional space is represented; j has a value of 1-3 and represents each dimension in three-dimensional space as well.

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

wherein 1/α is a viscous drag coefficient, C₂Is the coefficient of inertial resistance, D in equation (5)_ijthe constructed matrix can be represented by a diagonal matrix 1/α, C_ijThe constructed matrix may be passed through a diagonal matrix C₂And (4) showing.

The flow field v-pressure drop delta p is adopted to describe the characteristics of the porous medium unit, and the pressure loss parameter is calculated by the following formula:

Δp＝-S_id＝k₁v²+k₂v (7)

wherein, Δ p is the pressure drop between the windward side and the leeward side of the porous medium unit, v is the flow velocity of the fluid, ρ is the density of the fluid, and d is the thickness of the porous medium unit.

Substituting equation (6) into equation (7) and comparing with equation (7) can obtain,

determination of values of other parametersUnder the condition (2), the inertial resistance coefficient C of the porous medium unit can be determined according to the formula (8)₂and a viscous drag coefficient of 1/α.

Wherein the obtained pressure drop and velocity data can be used as physical characteristics of the porous medium unit model.

On the basis of the above embodiment, 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, an object of the embodiments of the present invention is to determine a method for quickly determining a preset inertial resistance coefficient and a preset viscous resistance coefficient, which may be applied to a plurality of different building units, that is, a porous medium unit corresponding to the preset inertial resistance coefficient and the preset viscous resistance coefficient determined by the method provided in the embodiments of the present invention may simulate a fixed type of building unit. The specific determination method is to determine by using preset parameters, and the preset parameters may include one or more of porosity, morphological parameters of the building units, wind environment in which the building units are located, or layout parameters of the building units in a corresponding calculation domain.

On the basis of the above embodiment, the preset inertial resistance coefficient and the preset viscous resistance coefficient may be calculated specifically as follows:

constructing a three-dimensional model of the porous medium unit with the target porosity based on preset software to simulate a target building single body with the target porosity, and determining a calculation domain and boundary conditions;

calculating a flow field and a pressure drop of the three-dimensional model based on the three-dimensional model of the porous medium unit with the target porosity, the calculation domain, and the boundary condition;

and determining the quantitative relation between the flow field and the pressure drop of the porous medium unit according to the flow field and the pressure drop of the three-dimensional model, and determining the inertial resistance coefficient and the viscous resistance coefficient of the porous medium unit.

Specifically, the preset software for constructing the three-dimensional model adopted in the embodiment of the present invention may be spacecham, NX (UG), AutoCAD, or SketchUp pro, the preset software for performing CFD numerical simulation may be ANSYS FLUENT, and the preset software for verifying that the porous medium unit can simulate the building element may be ANSYS discover live. The method includes the steps of selecting appropriate software according to the complexity of an object needing to build a three-dimensional model, and in the embodiment of the invention, the software is not particularly limited, and only SpaceMehaim 19.0 is taken as an example for explanation. The method for determining the preset inertial resistance coefficient and the preset viscous resistance coefficient provided by the embodiment of the invention is realized by only using the parameter of porosity, namely the preset inertial resistance coefficient and the preset viscous resistance coefficient are determined according to the porosity, and the porosity is determined based on preset software. The method comprises the following specific steps:

s11, firstly, carrying out three-dimensional modeling on the target building monomer in SpaceClaim19.0 software, wherein the model is in a windowing mode, and constructing a three-dimensional model of the cuboid porous medium unit with the target porosity so as to simulate the target building monomer with the target porosity.

And S12, establishing a calculation domain which is as large as the windward outer frame (namely the longitudinal section) of the porous medium unit, and respectively extending the front depth and the rear depth by 3-5 times of the spatial distance of the side length of the porous medium unit. Note that, a calculation area larger than the longitudinal section of the porous medium unit cannot be made here, because when the wind speed and the pressure drop of the air inlet surface of the porous medium unit are measured, it is necessary to ensure that all the inlet wind passes through the inside of the building ventilation duct, and if the inlet wind passes through the outside of the building, the result is inaccurate.

S13, setting a boundary condition. And (3) introducing the constructed three-dimensional model and the calculation domain into an ANSYS FLUENT, setting the wind speed of a wind environment to be 4m/s, setting the wind speeds of the upper space and the lower space to be the same, and setting the direction of the wind speed to be parallel to the normal of the windward side of the porous medium unit. At the leeward side (i.e., the boundary of the outlet of the wind) of the porous medium unit, the wind pressure is set to 1 atmospheric pressure reference value. Setting the turbulence model to a "k-epsilon" mode in ANSYSFLUENT; the surface of the porous medium unit is set to be a non-slip boundary, and the material of the porous medium unit is set to be 'solid'.

The material of the porous medium unit for setting the boundary condition is "solid", which is different from "full" of the fluid. Boundary conditions are divided into INLET, OUTLET, INTERNAL and WALL according to types, partitions and fluid objects are correspondingly classified, fluid is generally classified into INTERNAL, and a fixed WALL surface is classified into WALL.

S14, the solver initializes and calculates. And after the parameters are set, calculating the flow field and pressure drop indexes of the porous medium unit.

If the target porosity is 10% in S11, after S12-S14, the quantitative relationship between the flow field and the pressure drop obtained in S14 is determined, i.e., the flow field and the pressure drop are subjected to parameter fitting, for example, to obtain a binary quadratic equation shown in the following equation (9), then:

y＝83.767x²+3.1136x+M (9)

wherein y represents a flow field value, namely a wind speed value in a flow field, and the unit is m/s; x represents the pressure drop in pa; m is a constant, where M is 0, since a wind speed of 0M/s corresponds to a pressure drop of 0pa, so the constant term M in the fitting equation is 0.

Then there are:

wherein, C₂is the inertial resistance coefficient of the porous medium unit, 1/α is the viscous resistance coefficient of the porous medium unit, d is the thickness of the porous medium unit, rho is the fluid density, mu is a constant value 1.7894 x 10^-5。

When d is 9.49m, the fluid density (i.e. air density) rho is 1.225kg/m³Then, C can be obtained₂14.4112, and 18335.3, namely the preset inertia resistance coefficient and the preset viscosity resistance coefficient of the porous medium unit are obtained.

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

and S121, determining the boundary and the minimum grid unit. The constructed three-dimensional model and the calculation domain are led into an ICEM CFD19.0, the calculation domain with the windward side and the leeward side opposite to the porous medium unit is selected, firstly, an air inlet (IINLET), an air OUTLET (OUTLET), a WALL surface (WALL) and an inner part (INTERIOR) are created to be a calculation domain interface, and secondly, a 'body unit' is established, namely 'BUILDING' and 'FLUID', which are minimum volume units for constructing BUILDING entities and FLUIDs. The caliber of each hole of the porous medium unit is set to be 0.004, the maximum value (Max element) of the Global grid (Global Mesh) is set to be 0.002, and the minimum grid size (Part Mesh) is set to be 0.004/5-0.0008. It should be noted here that the setting of the minimum grid size is a result of balancing the two factors of computational efficiency and result quality.

And S122, setting a grid type and a grid generating method. The grid type is 'Quad Dominant', and the grid computing method is 'Patch Dependent'. And executing the grid generating command to generate 200 ten thousand grids.

Correspondingly, when the boundary condition is set in S13, the grid and the calculation domain of the three-dimensional model generated in S122 are imported into ANSYS FLUENT for subsequent processing, which is detailed in S13 and will not be described herein again in the embodiments of the present invention.

Specific explanation and experimental verification are carried out on whether the porosity, the morphological parameters of the building monomers, the wind environment of the building monomers or the layout parameters of the building monomers in the corresponding calculation domains are taken as preset parameters respectively, namely a method for determining the preset parameters is specifically explained.

On the basis of the above embodiment, the preset parameters in the building wind environment assessment method based on CFD numerical simulation provided in the embodiment of the present invention 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 determine a calculation domain and boundary conditions;

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.

Specifically, S21, three-dimensional modeling is performed on the building monomer in SpaceClaim19.0 software, the model is in a windowing mode, three cuboid porous medium units (namely, first-class sample porous medium units) with the same shape (namely, the same size) and different porosities are respectively constructed, and three-dimensional models are correspondingly obtained. When the porous medium unit simulates the building unit, the porous medium unit can only simulate the building unit with the same porosity as the porous medium unit.

S22, establishing a calculation domain which is as large as the windward outer frame (i.e. longitudinal section) of the first type of sample porous medium unit, and the front and back depths of the calculation domain are respectively prolonged by 3-5 times of the spatial distance of the side length of the first type of sample porous medium unit, and noting that the calculation domain with the longitudinal section larger than the first type of sample porous medium unit cannot be made, because it is necessary to ensure that the windward air completely passes through the inside of the building air duct, and the result is inaccurate if the windward air passes through the outside of the building body, as shown in FIG. 2, the region enclosed by the air inlet ①, the air outlet ①, the air inlet (ii) and the air outlet (ii) is the calculation domain, and the boundary of the calculation domain is internally.

And S23, determining the boundary and the minimum grid unit. Importing the three-dimensional model and the calculation domain into ICEMCFD19.0, selecting the calculation domain with the windward side and the leeward side opposite to the first type of sample porous medium unit, firstly creating a windward side air inlet (IINLET), a leeward side air OUTLET (OUTLET), a WALL surface (WALL) and an INTERIOR (INTERIOR) as calculation domain interfaces, and secondly establishing 'body units', namely 'BUILDING' and 'FLUID', which are minimum volume units for BUILDING entities and FLUIDs. The caliber of each hole of the first type sample porous medium unit is set to be 0.004, the maximum value (maxement) of the Global grid (Global Mesh) is set to be 0.002, and the minimum grid size (Part Mesh) is set to be 0.004/5-0.0008. It should be noted here that the setting of the minimum grid size is a result of balancing the two factors of computational efficiency and result quality.

S24, setting grid type and generating grid method. The grid type is 'Quad Dominant', and the grid computing method is 'Patch Dependent'. And executing the grid generating command to generate 200 ten thousand grids. When mesh division is performed by software, the three-dimensional model and the computational domain are divided into tetrahedral meshes (tetrahedrons) or polyhedral meshes (polyhydras), respectively.

And S25, importing the constructed three-dimensional model and the calculation domain into an ANSYS FLUENT, setting the wind speed of a wind environment to be 4m/S, setting the wind speeds of upper and lower spaces to be the same, and setting the direction of the wind speed to be parallel to the normal of the windward side of the first type sample porous medium unit. At the leeward side (i.e. the boundary of the outlet of the wind) of the first type sample porous medium unit, the wind pressure is set to be 1 atmosphere reference value. Setting the turbulence model to "k-epsilon" mode in ANSYS FLUENT; the surface of the first type sample porous medium unit is set to be a non-slip boundary, and the material of the first type sample porous medium unit is set to be 'solid'.

S26, the solver initializes and calculates. And after the parameters are set, calculating the flow field and the pressure field of the first type sample porous medium unit.

As shown in fig. 2, in the three-dimensional model of the first type of sample porous medium unit employed in the embodiment of the present invention, the three-dimensional model is a rectangular parallelepiped, and the cross-sectional shape in the longitudinal direction is a square. The length of the three-dimensional model is 12.65m, the width (namely the thickness of the first type of sample porous medium unit) and the height of the three-dimensional model are both 9.49m, 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, the ventilation windows are square, and the side length is 1 m.

Calculating to obtain the flow field and pressure field curves of the first type sample porous medium unit, as shown in fig. 3, wherein fig. 3(a) shows that the quadratic coefficient of the flow field pressure field curve of the first type sample porous medium unit with the porosity of 10% is k₁83.767, the first power coefficient is k₂A first type of porous media having a thickness of 9.49m and an air density of 1.225kg/m was used 3.1136³The inertial resistance coefficient C can be obtained from the formula (8)₂14.4112, and a viscous drag coefficient 1/α of 18335.3 FIG. 3(b) shows a flow field pressure curve of a first type sample porous medium element having a porosity of 20% and a square coefficient k₁16.992, the first power coefficient is k₂A first type of sample porous media was used having a thickness of 9.49m and an air density of 1.225kg/m 25.385³The inertial resistance coefficient C can be obtained from the formula (8)₂2.92329, and a viscous drag coefficient 1/α of 149487 FIG. 3(c) shows a flow field pressure curve of a first type sample porous medium element having a porosity of 30% and a square coefficient k₁7.4124, the first power coefficient is k₂The first sample porous media used had a thickness of 9.49m and an air density of 1.225kg/m, 0.173³The inertial resistance coefficient C can be obtained from the formula (8)₂1.27522, and a viscous drag coefficient of 1/α of 1018.76.

From the obtained results of the inertial resistance coefficient and the viscous resistance coefficient, it can be known that the inertial resistance coefficient and the viscous resistance coefficient of each first-type sample porous medium unit are different, and the target porosity of the target building monomer can influence the specific values of the inertial resistance coefficient and the viscous resistance coefficient, which indicates that the target porosity of the target building monomer can be used as a preset parameter to determine the preset inertial resistance coefficient and the preset viscous resistance coefficient of the porous medium unit.

On the basis of the above embodiment, the method for determining the preset parameters in the building wind environment assessment method based on CFD numerical simulation provided in the embodiment of the present invention further includes:

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 porous medium units as the preset parameters.

Specifically, S31, three-dimensional modeling is performed on the building unit in the spaceclaim19.0 software, and two porous medium units (i.e., the second type of porous medium unit) of a cube and a cuboid are respectively constructed to simulate the building unit of the cube sample and the building unit of the cuboid sample. And correspondingly obtaining two three-dimensional models, wherein each second type sample porous medium unit is a windowing mode with the porosity of 10%.

And S32, establishing calculation domains, wherein the two three-dimensional models correspond to the two calculation domains, the calculation domains are as large as the windward outer frames (namely the longitudinal sections) of the corresponding second type sample porous medium units, and the front and back depths are respectively prolonged by 3-5 times of the spatial distance of the side length of the second type sample porous medium units. Note that, the calculation domain having a vertical section larger than that of the second type sample porous medium unit cannot be made here because the space on both sides and above the second type sample porous medium unit cannot be added when the intake air speed and the pressure drop of the second type sample porous medium unit are measured, otherwise the result is affected.

S33-S36, identical to S23-S26.

Calculating to obtain flow field and pressure field curves of the second type sample porous medium unit, and drawing a flow field and pressure field curve chart, as shown in fig. 4, wherein fig. 4(a) is the flow field and pressure field curve of the cuboid second type sample porous medium unit with porosity of 10%, and the quadratic coefficient of the curve is k₁83.767, the first power coefficient is k₂A second type of porous media with a thickness of 9.49m and an air density of 1.225kg/m was used 3.1136³The inertial resistance coefficient C can be obtained from the formula (8)₂the value is 14.4112, the viscous drag coefficient 1/alpha is 18335.3, and the quadratic coefficient k of the flow field pressure field curve of the second type of the square sample porous medium unit with the porosity of 10 percent in FIG. 4(b)₁89.148, the first power coefficient is k₂A second type of sample porous media was used having a thickness of 9.49m and an air density of 1.225kg/m 3.7195³The inertial resistance coefficient C can be obtained from the formula (8)₂15.3369, and a viscous drag coefficient of 1/α of 19481.2.

From the results of the inertial resistance coefficient and the viscous resistance coefficient obtained above, it can be known that the difference between the inertial resistance coefficient and the viscous resistance coefficient of each second-type sample porous medium unit is not large, the relative error Δ/L is in the order of 10 to the power of-1, and the inertial resistance coefficient and the viscous resistance coefficient can be considered to be equal within the error allowable range. The morphological parameters of the target building monomer are shown not to influence the specific values of the inertial resistance coefficient and the viscous resistance coefficient, and the morphological parameters of the target building monomer are shown not to be used as preset parameters to determine the preset inertial resistance coefficient and the preset viscous resistance coefficient of the porous medium unit.

On the basis of the above embodiment, the determining method in the building wind environment assessment method based on CFD numerical simulation provided in the embodiment of the present invention further includes:

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.

Specifically, in the embodiment of the present invention, two sample architectural monomers with the same porosity of 10% and two third sample porous medium units are taken as examples for explanation, and each third sample porous medium unit is respectively used to simulate a sample architectural monomer. Wherein two sample building monomers are respectively for windowing the square and the cuboid of windowing, and are diagonal distribution, and the wall of two third type sample porous medium units is respectively for wall square and wall cuboid, and is diagonal distribution. In the embodiment of the invention, the third type of sample porous medium unit needs to be subjected to fluid mechanics simulation in wind environments with different wind directions and wind speeds, wherein the fluid mechanics simulation comprises at least four working conditions: the wind direction is straight in, the wind direction is rotated by 135 degrees, the wind speed is 2m/s (2-level wind), and the wind speed is 4m/s (3-level wind), so that the window opening mode is compared with the porous medium unit wall surface entity under different wind environments, and a corresponding flow field and a pressure field are obtained.

Taking the wind direction straight-in as an example, the flow field and the pressure field of the wind direction straight-in windowing mode and the flow field and the pressure field of the porous medium unit wall surface entity are obtained.

Specifically, S41, building monomers are subjected to three-dimensional modeling in SpaceClaim19.0 software, a windowing mode model of the sample building monomers and a wall surface model of a third type of sample porous medium units are respectively constructed, wherein the window mode model and the wall surface model are distributed in a cube and a cuboid diagonal line, and the porosity is 10%.

And S42, establishing a calculation domain, reserving enough calculation domains on the windward outer side frames of the sample building single bodies and the third type of sample porous medium units, wherein the side length of the calculation domains is 3-5 times of that of the sample building single bodies and the third type of sample porous medium units, so as to ensure that the turbulent flow is fully developed and flows.

S43, determining a boundary and a minimum grid unit, importing a windowing mode model, a wall model and a calculation domain into ICEMCFD19.0, considering the changing wind direction, needing to set two air INLETs (INLET), and similarly needing to set two air OUTLETs (OUTLET). in the embodiment of the invention, when the wind direction is horizontal 0 degrees, the wind direction is vertical to the windward side, at the moment, an air INLET ① and an air OUTLET ① ' are selected, 1 atmospheric pressure reference value is set at the windward side at the boundary of the air OUTLET ① ', when the wind direction is inclined to the wind 45 degrees, the wind direction is different from that when the wind direction is horizontal 0 degrees, the wind direction forms an included angle with the normal of the windward side, the air INLET ① and the air OUTLET ① ' are selected, when the wind environment parameter changes, the two air INLETs are set at the same time, the air OUTLET corresponding to each air INLET is set as the air INLET ① and the air OUTLET ① ', the air OUTLETs are set as the air INLET ① and the air OUTLET ① ', the rest faces are set as the minimum grid size of the window of the windowing mode model, and the grid (Mesh) is set as maximum Mesh (002).

S44, setting grid type and generating grid method. The grid type is 'Quad Dominant', and the grid computing method is 'Patch Dependent'. And executing the grid generating command to generate 200 ten thousand grids.

S45, setting a boundary condition. And guiding the generated grids into FLUENT, setting the wind speed of the wind environment to be 4m/s, setting the wind speeds of the upper space and the lower space to be the same, and setting the initial wind direction to be parallel to the normal of the windward side. Setting the wind pressure to be 1 atmospheric pressure reference value at the leeward side (namely the outlet boundary of the wind) of the third type sample porous medium unit and at the leeward side (namely the outlet boundary of the wind) of the sample building monomer; the turbulence model is a 'k-epsilon' mode; the surfaces of the windowing mode model and the wall surface model are set to be non-slip boundaries, and the materials are set to be solid.

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

S46, the solver initializes and calculates. And after the parameters are set, calculating the first type of flow field distribution obtained by the windowing model under different wind environment parameters and the second type of flow field distribution obtained by the wall surface model. As shown in fig. 5, fig. 5(a) is a contour map of the first type flow field distribution when the wind direction is parallel to the normal of the windward side and the wind speed is 2m/s, and fig. 5(b) is a contour map of the second type flow field distribution when the wind direction is parallel to the normal of the windward side and the wind speed is 2 m/s. Comparing fig. 5(a) and fig. 5(b), it can be seen that the first type flow field distribution and the second type flow field distribution are consistent when the wind direction is parallel to the normal of the windward side and the wind speed is 2 m/s. Fig. 5(c) is a contour map of the first type of flow field distribution when the included angle between the wind direction and the normal of the windward side is 135 degrees and the wind speed is 4m/s, and fig. 5(d) is a contour map of the second type of flow field distribution when the included angle between the wind direction and the normal of the windward side is 135 degrees and the wind speed is 4 m/s. As can be seen from the comparison between fig. 5(c) and fig. 5(d), when the included angle between the wind direction and the normal line of the windward side is 135 ° and the wind speed is 4m/s, the situation of the first type of flow field distribution is consistent with that of the second type of flow field distribution, which indicates that the wind environment parameter cannot be used as the preset parameter, that is, the wind environment of the target building unit does not affect the specific values of the inertial resistance coefficient and the viscous resistance coefficient, and indicates that the wind environment parameter of the wind environment of the target building unit cannot be used as the preset parameter to determine the preset inertial resistance coefficient and the preset viscous resistance coefficient of the porous medium unit.

It should be noted here that when comparing the flow field distributions, certain errors exist in the velocity values of the same spatial position in the two flow field distributions, and the situation of the flow field distributions can be considered to be consistent within an error allowable range, and generally, the relative error needs to be controlled to be in the order of 0.1.

On the basis of the foregoing embodiment, in the building wind environment assessment method based on CFD numerical simulation provided in the embodiment of the present invention, the determination method further includes:

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 a calculation domain and boundary conditions;

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 flow field is inconsistent with that of the fourth type flow field, taking the layout parameters of the wall models in the calculation domain as the preset parameters.

Specifically, the embodiment of the invention is used for determining whether the layout parameters of the target building unit in the corresponding calculation domain can be used as the preset parameters.

Taking sample building units with the porosities of 10%, 20% and 30% as examples, the windowed cube and the windowed cube were studied under the condition of any layout and any wind direction and any wind speed, and the wall cube of the fourth type sample porous medium unit were studied under the condition of the same layout and the same wind direction and the same wind speed as those of the windowed cube and the windowed cube. This requires hydrodynamic simulation of the model under any layout and wind environment changes, which includes at least four conditions: under the conditions of wind direction 0 degrees, wind direction 45 degrees, wind speed 2m/s and wind speed 4m/s, sample building monomer combinations with different porosities are randomly distributed, fourth type sample porous medium unit combinations with different porosities are randomly distributed, the conditions of 2 x 2 comparison are totally obtained, comparison of the windowing mode model and the wall surface model of the fourth type sample porous medium unit in different block forms and external environment changes is obtained, and the detection indexes adopt flow fields, pressure fields and sample points to acquire data.

The method comprises the steps of collecting flow fields and pressure fields which are randomly distributed on a windowing mode model of a sample building monomer with the porosity of 10%, 20% and 30% under the conditions of wind direction 0 degrees and wind speed 2m/s, collecting flow fields and pressure fields which are distributed on a wall surface model of a fourth type sample porous medium unit with the porosity of 10%, 20% and 30% under the conditions of wind direction 0 degrees and wind speed 2m/s and are the same as the windowing mode model, and collecting data collected by a part of sample points to perform quantitative inspection. The implementation steps are as follows:

s51, carrying out three-dimensional modeling on the building monomers in SpaceClaim19.0 software, and respectively constructing a windowing mode model of three sample building monomers with any layout and a wall surface model of a fourth type sample porous medium unit with the same layout, wherein the porosity in each layout is respectively 10%, 20% and 30%. It should be noted that each layout corresponds to a layout parameter, and the layout parameter is used to characterize the layout.

And S52, establishing a calculation domain, reserving enough calculation domains on the windward outer side frames of the sample building single bodies and the fourth type of sample porous medium units, wherein the side length of the calculation domains is 3-5 times of that of the sample building single bodies and the fourth type of sample porous medium units, so as to ensure that the turbulent flow is fully developed and flows.

S53, determining a boundary and a minimum grid unit, and importing a wall model, a windowing model and a calculation domain into ICEMCFD19.0. because the wind direction is considered to be changed, two air INLETs (INLET) are needed to be arranged, and similarly, two air OUTLETs (OUTLET) are needed, wherein in the embodiment of the invention, when the wind direction is horizontal 0 degrees, the wind direction is vertical to the windward side, at the moment, an air INLET ② and an air OUTLET ② ' are selected, 1 atmospheric pressure reference value is arranged at the windward side at the boundary of the air OUTLET ② ', when the wind direction is inclined to the wind direction by 45 degrees, the wind direction is different from that when the wind direction is horizontal 0 degrees, the wind direction forms an included angle with the normal line of the windward side, the air INLET ② and the air OUTLET ② ' are selected, when the wind environment parameter is changed, the two air INLETs are simultaneously arranged, the air OUTLET corresponding to each air INLET is arranged, namely, when the air INLETs are arranged as the wind direction is arranged as the wind direction, the air INLETs are arranged as the air INLET ② and the air OUTLET ②, the air OUTLETs are arranged as the minimum grid size of the window model, and the grid (Mesh) is arranged as Global Mesh (002).

S54, setting grid type and generating grid method. The grid type is 'Quad Dominant', and the grid computing method is 'Patch Dependent'. And executing the grid generating command to generate 200 ten thousand grids.

S55, setting a boundary condition. And guiding the generated grids into FLUENT, setting the wind speed of the wind environment to be 2m/s, setting the wind speeds of the upper space and the lower space to be the same, and setting the initial wind direction to be parallel to the normal of the windward side. Setting the wind pressure to be 1 atmospheric pressure reference value at the leeward side (namely the outlet boundary of the wind) of the fourth type sample porous medium unit and at the leeward side (namely the outlet boundary of the wind) of the sample building single body; the turbulence model is a 'k-epsilon' mode; the surfaces of the windowing mode model and the wall surface model are set to be non-slip boundaries, and the materials are set to be solid.

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

S56, the solver initializes and calculates. And after the parameters are set, calculating third type 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 determining fourth type flow field distribution of the windowing mode models corresponding to any layout parameters in the calculation domain under the same wind environment parameters. As shown in fig. 6, fig. 6(a) is a contour diagram of the third type flow field distribution when the wind direction is parallel to the normal of the windward side and the wind speed is 2m/s, and fig. 6(b) is a contour diagram of the fourth type flow field distribution when the wind direction is parallel to the normal of the windward side and the wind speed is 2 m/s. Comparing fig. 6(a) and fig. 6(b), it can be seen that the third type flow field distribution and the fourth type flow field distribution are consistent when the wind direction is parallel to the normal of the windward side and the wind speed is 2 m/s. Fig. 6(c) is a contour map of the third type of flow field distribution when the included angle between the wind direction and the normal of the windward side is 45 ° and the wind speed is 4m/s, and fig. 6(d) is a contour map of the fourth type of flow field distribution when the included angle between the wind direction and the normal of the windward side is 45 ° and the wind speed is 4 m/s. As can be seen from the comparison between fig. 6(c) and fig. 6(d), when the included angle between the wind direction and the normal line of the windward side is 45 ° and the wind speed is 4m/s, the situation of the third type of flow field distribution is consistent with that of the fourth type of flow field distribution, which indicates that the layout parameter of the target building unit in the corresponding calculation domain cannot be used as the preset parameter, that is, the layout parameter of the target building unit in the corresponding calculation domain does not affect the specific values of the inertial resistance coefficient and the viscous resistance coefficient, and indicates that the layout parameter of the target building unit in the corresponding calculation domain cannot be used as the preset parameter to determine the preset inertial resistance coefficient and the preset viscous resistance coefficient of the porous medium unit.

The invention aims to provide a building wind environment assessment method of a 'porous medium unit' which accords with a natural cross wind or artificial ventilation effect of a real building by utilizing fluid mechanics simulation. The wind environment assessment method provided by the embodiment of the invention is used for simulating the ventilation condition of the urban building group, and compared with the simulation of the whole modeling of an indoor windowing three-dimensional entity, the calculation amount is greatly reduced.

The embodiment of the invention discloses a building wind environment assessment method considering a building body flow-through effect, and belongs to the technical field of hydrodynamics numerical simulation of building wind environments. The problem of dynamic air circulation around the form diversity of the building monomers is solved, the dilemma that the 'cross wind' or 'artificial ventilation' effect of a high-density building cannot be reflected in numerical simulation is solved, and the method has positive significance for constructing the 'air-permeable' building monomers and improving the simulation precision of the urban building monomers. The key technical points of the invention are as follows: considering the drag force between gas-solid two-phase flows in the building monomer, the embodiment of the invention provides a processing method for simulating the building monomer by adopting a porous medium unit, wherein the simulated porous medium is embodied by adding a momentum source term into a standard fluid equation, a mathematical equation set of the porous medium unit suitable for turbulent flow among urban building groups is established by adopting a volume averaging technology and a k-epsilon turbulent flow simulation technology, and the effectiveness of a model is verified by utilizing the space volume average of a micro-scale numerical simulation calculation result. In the embodiment of the invention, the relation between the wind speed and the pressure drop and the porosity of the building single body is described quantitatively by adopting a CFD numerical simulation method, and the condition that the porous medium unit can simulate the building single body is determined, so that the condition is irrelevant to the wind environment, the form of the building single body and the layout in a calculation domain and is only relevant to the porosity of the building single body, the thickness of the porous medium unit and the flow resistance characteristic of the porous medium. Compared with the three-dimensional simulation calculation amount of the real-scene indoor shelter, the method provided by the embodiment of the invention is greatly reduced, and is expected to push the general building and block scale (<1km) of high-precision CFD numerical simulation calculation to the urban scale (<10km), thereby providing scientific evidence for city planning designers and governments to decide and construct sustainable cities of resources.

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

the wind environment evaluation module 71 is configured to perform computational fluid dynamics CFD numerical simulation on a target building unit based on a porous medium unit, and determine a wind speed of a calculation domain and a pressure drop between an air inlet and an air outlet of the calculation domain to evaluate a flow field and a pressure drop around the target building unit; 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.

Specifically, the functions, processing flows, and technical effects of the modules in the building wind environment assessment system based on CFD numerical simulation provided in the embodiment of the present invention correspond to the method embodiments one to one, and are not described herein again in the embodiment of the present invention.

On the basis of the above embodiment, an embodiment of the present invention further provides a building wind environment assessment apparatus 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, which when invoked by the processor are capable of performing the method of fig. 1.

On the basis of the above embodiments, there is also provided in an embodiment of the present invention a non-transitory computer-readable storage medium storing computer instructions that cause the computer to perform the method described in fig. 1.

The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

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

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;

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

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:

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;

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;