CN114510858A - Flow field determination method, equipment and medium based on non-Newtonian fluid - Google Patents
Flow field determination method, equipment and medium based on non-Newtonian fluid Download PDFInfo
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Abstract
The embodiment of the specification discloses a flow field determination method, equipment and medium based on non-Newtonian fluid, wherein the method comprises the following steps: determining the corresponding fluid viscosity of the non-Newtonian fluid under different shear rates through a pre-constructed non-Newtonian fluid rheological model, wherein the non-Newtonian fluid rheological model is used for describing the corresponding relation between the viscosity and the shear rate of the non-Newtonian fluid; establishing an initial coating die head flow field equation in the coating process of the non-Newtonian fluid; determining initial conditions and boundary conditions of an initial coating die head flow field equation according to the characteristics of non-Newtonian fluid so as to determine the coating die head flow field equation meeting the requirements; the corresponding fluid viscosity under different shear rates is input into a coating die head flow field equation meeting the requirements, the flow field of the non-Newtonian fluid is determined, and the non-Newtonian fluid is modeled by combining a fluid model and the coating die head flow field equation, so that the coating process of the non-Newtonian fluid can be simulated more truly, and more accurate flow field conditions are obtained.
Description
Technical Field
The present disclosure relates to the field of computer technologies, and in particular, to a flow field determination method, device, and medium based on non-newtonian fluids.
Background
In recent years, with the rapid development of various components such as liquid crystal screens and solar panels, the development of coating techniques has been receiving attention. The coating is a key process which directly influences the capacity and consistency of the product, and the high molecular organic functional material is coated on the base material in the process design of the product.
In the existing coating technology, the coating material is mostly Newtonian fluid, and the simulation calculation is also focused on the simulation of the Newtonian fluid coating process. The existing research model mostly adopts commercial software to calculate the flow field, a fluid constitutive equation library of the software only supports Newtonian fluid, and the prior art is difficult to accurately calculate the flow field of non-Newtonian fluid.
Disclosure of Invention
One or more embodiments of the present specification provide a flow field determination method, device and medium based on non-newtonian fluid, which are used to solve the following technical problems: the prior art is difficult to accurately calculate the flow field of the non-Newtonian fluid.
One or more embodiments of the present disclosure adopt the following technical solutions:
one or more embodiments of the present description provide a non-newtonian fluid-based flow field determination method, the method comprising: determining corresponding fluid viscosity of the non-Newtonian fluid under different shear rates through a pre-constructed non-Newtonian fluid rheological model, wherein the non-Newtonian fluid rheological model is used for describing the corresponding relation between the fluid viscosity and the shear rate of the non-Newtonian fluid; establishing an initial coating die head flow field equation in the coating process of the non-Newtonian fluid; determining initial conditions and boundary conditions of the initial coating die head flow field equation according to the characteristics of the non-Newtonian fluid so as to determine the coating die head flow field equation meeting the requirements; and inputting the corresponding fluid viscosity under different shear rates into the flow field equation of the coating die head meeting the requirements, and determining the flow field of the non-Newtonian fluid.
Further, before determining the corresponding fluid viscosities of the non-newtonian fluid at different shear rates through a pre-constructed rheological model of the non-newtonian fluid, the method further comprises: acquiring fluid rheological property experimental curves of organic solute, organic solution and water under different conditions in advance; and determining a non-Newtonian fluid rheological model according to the rheological property experimental curve and a plurality of preset rheological equations.
Further, determining a non-Newtonian fluid rheological model according to the experimental rheological property curve and a plurality of preset rheological equations, specifically, dividing the experimental rheological property curve of the fluid into a plurality of curves according to a preset dividing mode; fitting each curve with the multiple preset rheological equations respectively, calculating fitting errors of the multiple preset rheological equations on each curve, and selecting the preset rheological equation with the minimum fitting error as the rheological equation under the corresponding experimental condition of each curve; and determining a plurality of rheological equations corresponding to the experimental curve of the fluid rheological property, and determining the plurality of rheological equations as the non-Newtonian fluid rheological model.
Further, the determining of the initial conditions of the initial coating die flow field equation specifically includes: setting initial conditions corresponding to the coating liquid state in the initial coating die head flow field equation and initial conditions corresponding to the coating process state; wherein, the initial conditions corresponding to the liquid applying state comprise: setting the masking liquid to be incompressible fluid, setting the masking liquid to be isotropic fluid and setting the masking liquid to be single-phase fluid; the initial conditions corresponding to the coating process state comprise that the coating process is set to be an isothermal process and the rheological law in the coating process is set to be constant.
Further, the boundary conditions include: a boundary condition corresponding to an inlet boundary of the die head, a boundary condition corresponding to an outlet boundary of the die head, and a boundary condition corresponding to a solid wall boundary of the die head; wherein the boundary condition of the inlet boundary of the die head is set as
U0In the form of an inlet velocity profile,
is an inletA volumetric flow rate; the boundary condition of the outlet boundary of the die head is set as
p＝peU is the flow velocity, n is the flow velocity along the normal to the exit cross-section, peIs the ambient pressure; the boundary condition of the solid wall boundary of the die head is set as
twIs a unit tangent vector at the fixed wall, nwIs the unit external normal vector at the fixed wall.
Further, the determining the flow field of the non-newtonian fluid specifically includes: performing three-dimensional format conversion on the coating die head flow field equation according to a preset solving algorithm to obtain a plurality of corresponding three-dimensional format equations, wherein the type of the preset solving algorithm comprises a decoupling solving algorithm; and carrying out finite element discretization on the three-dimensional format equation to obtain a corresponding discretization result so as to calculate the flow field of the non-Newtonian fluid according to the discretization result.
Further, when the type of the preset solution method is decoupling solution, the three-dimensional format conversion is performed on the coating die head flow field equation to obtain a plurality of corresponding three-dimensional format equations, and the method specifically comprises the following steps: decoupling the fluid velocity and the fluid pressure in the coating die head flow field equation to obtain an intermediate velocity expression and a pressure expression in the coating die head; correcting the intermediate speed expression according to the pressure expression to obtain a speed correction expression; and taking the intermediate speed expression, the pressure expression and the speed correction expression as a three-dimensional format equation.
Further, the performing finite element discretization on the three-dimensional format equation to obtain a corresponding discretization result specifically includes: respectively carrying out finite element dispersion on the intermediate speed expression, the pressure expression and the speed correction expression, and determining an intermediate speed dispersion result, a pressure dispersion result and a correction speed dispersion result; and calculating the intermediate speed dispersion result, the pressure dispersion result and the corrected speed dispersion result through a finite element dispersion algorithm to obtain the flow field of the non-Newtonian fluid.
One or more embodiments of the present description provide a non-newtonian fluid-based flow field determination device, comprising:
at least one processor; and the number of the first and second groups,
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor to enable the at least one processor to:
determining corresponding fluid viscosity of the non-Newtonian fluid under different shear rates through a pre-constructed non-Newtonian fluid rheological model, wherein the non-Newtonian fluid rheological model is used for describing the corresponding relation between the fluid viscosity and the shear rate of the non-Newtonian fluid; establishing an initial coating die head flow field equation in the coating process of the non-Newtonian fluid; determining initial conditions and boundary conditions of the initial coating die head flow field equation according to the characteristics of the non-Newtonian fluid so as to determine the coating die head flow field equation meeting the requirements; and inputting the corresponding fluid viscosity under different shear rates into the flow field equation of the coating die head meeting the requirements, and determining the flow field of the non-Newtonian fluid.
One or more embodiments of the present specification provide a non-transitory computer storage medium storing computer-executable instructions configured to:
determining corresponding fluid viscosity of the non-Newtonian fluid under different shear rates through a pre-constructed non-Newtonian fluid rheological model, wherein the non-Newtonian fluid rheological model is used for describing the corresponding relation between the fluid viscosity and the shear rate of the non-Newtonian fluid; establishing an initial coating die head flow field equation in the coating process of the non-Newtonian fluid; determining initial conditions and boundary conditions of the initial coating die head flow field equation according to the characteristics of the non-Newtonian fluid so as to determine the coating die head flow field equation meeting the requirements; and inputting the corresponding fluid viscosity under different shear rates into the flow field equation of the coating die head meeting the requirements, and determining the flow field of the non-Newtonian fluid.
The embodiment of the specification adopts at least one technical scheme which can achieve the following beneficial effects:
the rheological property of the fluid is described by constructing a fluid rheological model, a coating die head flow field equation which meets the requirement is determined according to the coating process and the fluid property, and the non-Newtonian fluid is modeled by combining the fluid model and the coating die head flow field equation, so that the coating process of the non-Newtonian fluid can be simulated more truly, and the more accurate flow field condition is obtained.
Drawings
In order to more clearly illustrate the embodiments of the present specification or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments described in the present specification, and for those skilled in the art, other drawings can be obtained according to the drawings without any creative effort. In the drawings:
fig. 1 is a schematic flow chart of a flow field determination method based on a non-newtonian fluid according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a flow field determination device based on a non-newtonian fluid according to an embodiment of the present disclosure.
Detailed Description
In order to make those skilled in the art better understand the technical solutions in the present specification, the technical solutions in the embodiments of the present specification will be clearly and completely described below with reference to the drawings in the embodiments of the present specification, and it is obvious that the described embodiments are only a part of the embodiments of the present specification, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present specification without any creative effort shall fall within the protection scope of the present specification.
In recent years, with the rapid development of various components such as liquid crystal screens and solar panels, the development of coating technology has attracted much attention, coating is a key process directly influencing the capacity and consistency of products, and high molecular organic functional materials are coated on a base material in the process design of the products. Under different coating environments, the flow field distribution of coating liquid is different, and the flow fields corresponding to different types of coating liquid are different; in addition, the flow field of the coating liquid is also closely related to the coating manner. Therefore, the flow field distribution of the entire coating liquid is very complicated and has many influence factors in the coating system.
Among coating techniques, slit coating, which is applied to optical film and paper production as a rapid and precise pre-metered coating technique, is a desirable high-precision coating technique. The demand for coating mechanism and process parameter setting is in conflict with the laggard mode of long-term process exploration depending on the experience of engineers in actual production. In the existing coating technology, most coating materials are Newtonian fluid, simulation calculation also focuses on simulation of the coating process of the Newtonian fluid, the existing research model mostly adopts commercial software to calculate the flow field, the fluid constitutive equation library of the software only supports the Newtonian fluid, and the existing technology is difficult to accurately calculate the flow field of the non-Newtonian fluid.
The embodiment of the present specification provides a flow field determination method based on a non-newtonian fluid, and an execution main body may be a server or any processing device with processing capability. It should be noted that the non-newtonian fluid herein may be a fluid having shear-thinning characteristics. The shear-thinning property means that the viscosity value of the fluid decreases when the shear rate increases, and the viscosity value of the fluid increases when the shear rate decreases. Fig. 1 is a schematic flow chart of a flow field determination method based on a non-newtonian fluid according to an embodiment of the present disclosure, and as shown in fig. 1, the method mainly includes the following steps:
and S101, determining the corresponding fluid viscosity of the non-Newtonian fluid under different shear rates through a pre-constructed rheological model of the non-Newtonian fluid.
In the actual research process of the non-newtonian fluid, since the viscosity of the non-newtonian fluid with the shear-thinning characteristic changes at different shear rates, a rheological model of the non-newtonian fluid needs to be constructed so as to determine the corresponding fluid viscosity of the non-newtonian fluid at different shear rates through the rheological model of the non-newtonian fluid. In the existing research, when a fluid model is constructed, any one rheological constitutive model is mostly adopted as the fluid model to be used, but the adoption of a single constitutive model can cause larger model error and can not better simulate the rheological characteristics of the fluid.
In an embodiment of the present specification, an adaptive piecewise constitutive model is provided, and a fluid rheological model with a small fitting error is obtained through a fluid rheological experimental curve and a plurality of preset rheological equations, so as to better simulate rheological characteristics of a fluid.
In one embodiment of the present disclosure, fluid rheological experimental curves of an organic solute, an organic solution, and water under different conditions are obtained and divided into a plurality of curves according to a preset division manner. The dividing method here may be a bisection method, in which the slopes of a plurality of points in the fluid rheology experimental curve are calculated, and the two curves are obtained by dividing the curve by taking the point with the largest slope as the center. The fluid rheological property experimental curve can also be divided into a plurality of curves by adopting an equidistant dividing mode, and the dividing mode of the fluid rheological property experimental curve in the embodiment of the specification is not particularly limited.
Further, a non-Newtonian fluid rheological model is determined according to the rheological experiment curve and a plurality of preset rheological equations. It should be noted that the preset rheological equations may be a structural viscous rheological equation, a structural viscous rheological three-parameter rheological equation, a high molecular viscosity equation, a Cross model, a hyperbolic reaction kinetics equation, or other fluid constitutive equations. Next, taking the bisection method as an example, after two curves are obtained, it is assumed that the two curves are curve a and curve B, respectively. Fitting the curve A with a plurality of preset rheological equations, calculating fitting errors of the preset rheological equations on the curve A, selecting the preset rheological equation with the minimum fitting error as the rheological equation of the curve A under the corresponding experimental condition, and assuming that the selected preset rheological equation with the minimum fitting error is the structural viscosity rheological equation. And calculating the fitting errors of the preset rheological equations on the curve B, selecting the preset rheological equation with the minimum fitting error as the rheological equation of the curve B under the corresponding experimental condition, and assuming that the selected preset rheological equation with the minimum fitting error is the polymer viscosity equation. And taking the structural viscosity rheological equation and the high molecular viscosity equation as a non-Newtonian fluid rheological model.
In an embodiment of the present specification, the experimental curve may be fitted by a plurality of preset rheological equations, and the global error of each rheological equation may be calculated. And judging whether the global error of each rheological equation is within a preset error threshold range, and if a plurality of rheological equations are within the error range, selecting one rheological equation with the minimum error as a non-Newtonian fluid rheological model. If the errors of the preset rheological equations are all higher than the threshold value, calculating the slope of a fluid rheological experiment curve, selecting the place with the maximum slope to carry out halving, respectively fitting the halved place with the preset rheological equations higher than the threshold value, if a plurality of functions meet the error threshold value, selecting one preset rheological equation with the minimum error, if the errors are all higher than the threshold value, continuously solving the slope at the section to carry out halving until the preset rheological equation with the minimum error is selected, and taking the preset rheological equation with the minimum error as a non-Newtonian fluid rheological model.
Through the method for determining the rheological model of the non-Newtonian fluid, provided by the embodiment of the specification, the rheological equation with the minimum error can be selected according to experimental data to simulate the property of the fluid, so that the accuracy of a simulation result is improved.
Step S102, establishing an initial coating die head flow field equation in the non-Newtonian fluid coating process.
In one embodiment of the present description, the Navier-Stokes equations (NS equations) are generally selected based on the properties of the non-Newtonian fluid during the coating process. The NS equation is a motion equation describing conservation of momentum of a viscous incompressible fluid, and is taken as an initial coating die flow field equation. Here, the coating process is slot coating, which may be referred to as slot coating.
And S103, determining initial conditions and boundary conditions of an initial coating die head flow field equation according to the characteristics of the non-Newtonian fluid so as to determine the coating die head flow field equation meeting the requirements.
Describing the motion of the fluid in the die using the NS equation requires setting of initial conditions for the NS equation in combination with the characteristics of the non-newtonian fluid and in combination with production practice experience, environmental analysis, and theoretical analysis.
In one embodiment of the present description, during slot coating, the dope injection flow at the coating die inlet is small, and the inside of the coating die cavity is approximately at atmospheric pressure, thus setting the dope incompressible fluid. In slot coating processes, the flow process of the fluid is slow, the heat of strain generated by energy dissipation is negligible, and in addition, the production environment temperature is kept basically constant, so the coating process is set to be an isothermal process. In addition, the coating liquid is usually diluted high polymer solution, the mutual entanglement among macromolecules is weak, and the coating liquid has similar mechanical response behaviors along all directions, so the coating liquid can be set to be isotropic fluid. Further, since the coating liquid is already uniformly mixed at the time of entering the die, no interphase action such as phase separation occurs during the coating process, and no chemical reaction occurs, the coating liquid is set to be a single-phase fluid. Finally, the physical properties of the coating solution are stable during the coating process, so that the rheological law is set to be constant during the coating process.
In order to obtain a unique solution of the NS equation, the boundary conditions of the NS equation must be set, and the setting of the boundary conditions directly affects the solving process and the obtained equation solution. In one embodiment of the present description, in connection with the coating process, the boundary of the internal flow field may be divided into three portions, an inlet, an outlet, and a solid wall of the mold cavity. The setting methods of these three part boundary conditions are discussed separately below.
First is the boundary condition of the entry boundary,assuming the inlet is circular with a radius r, the inlet volume flow rate is
Where n isinIs the unit normal vector of the inlet cross section in the flow direction. The inlet velocity has two options, constant and parabolic. In the constant case, the inlet velocity is:
in the case of a paraboloid, the inlet velocity is:
u＝U0nin (2)
wherein U is0Is a space paraboloid and needs to satisfy the formula (3)
D is the inlet cross-sectional area, when the center of the inlet cross-section is taken as the origin of coordinates O, the plane of the cross-section is an xOy coordinate plane, and the positive direction of the z-axis is parallel to ninThen U can be replaced0Is arranged as
U0＝z＝a(r2-x2-y2) (4)
Where a is the parameter to be determined. Due to the fact that
So as to obtain
Further obtaining an inlet velocity profile of
Additionally, if the inlet pressure is known, pressure boundary conditions may also be given. Equation (7) is taken as the boundary condition of the entry boundary.
Secondly, the boundary conditions of the outlet boundary, which are always assumed to be stable at the outlet, the flow velocity being in the direction n normal to the outlet cross-sectionoutNo change occurs, and equation (8) is satisfied, where equation (8) is as follows:
the outlet pressure is taken directly as the external ambient pressure, i.e. p ═ pe，peThe ambient pressure is typically 1 standard atmosphere. However, in a negative pressure environment, the value is required according to the actual situation.
Finally, the boundary condition of the solid wall boundary is that the fluid adheres to the solid surface during the flow. Therefore, the solid-liquid interface generally has a non-slip boundary condition, and satisfies the following conditions:
and S104, inputting the corresponding fluid viscosity under different shear rates into a coating die head flow field equation meeting the requirements, and determining the flow field of the non-Newtonian fluid.
In an embodiment of the present specification, a three-dimensional format conversion is performed on a coating die flow field equation according to a preset solution algorithm to obtain a plurality of corresponding three-dimensional format equations, where the preset solution algorithm may be a decoupling solution algorithm or a coupling solution algorithm.
The equation calculation process is explained by taking a decoupling solution algorithm as an example. Decoupling the fluid speed and the fluid pressure in the coating die head flow field equation to obtain an intermediate speed expression and a pressure expression in the coating die head, correcting the intermediate speed expression according to the pressure expression to obtain a speed correction expression, and finally taking the intermediate speed expression, the pressure expression and the speed correction expression as a three-dimensional format equation.
Wherein the intermediate speed expression includes formula (10), formula (11), and formula (12):
the pressure expression is shown in equation (13):
the velocity correction expression is shown as equation (14), equation (15), and equation (16):
in an embodiment of the present specification, the intermediate speed expression, the pressure expression, and the speed correction expression are respectively subjected to finite element discretization, an intermediate speed discretization result, a pressure discretization result, and a corrected speed discretization result are determined, and the intermediate speed discretization result, the pressure discretization result, and the corrected speed discretization result are calculated by a finite element discretization algorithm to obtain a flow field of the non-newtonian fluid.
The intermediate speed expressions, formula (10), formula (11), and formula (12), are discretized to obtain formula (17), formula (18), and formula (19), respectively, as follows:
dispersing the pressure expression formula (13) to obtain a pressure dispersion result:
discretizing the speed correction expression, namely an expression (14), an expression (15) and an expression (16) respectively to obtain a speed correction discrete result, wherein the expression (21), the expression (22) and the expression (23):
in one embodiment of the present description, in addition to the decoupling solution algorithm, the velocity and the pressure may be coupled together by a coupling solution algorithm to be solved, and the system of equations obtained is generally large in scale. The coupled algorithm has high complexity, high realization difficulty and higher calculation cost than the step-by-step algorithm. However, for the problem of steady-state solution, the algorithm can remove the time term and only needs dozens of iterations to obtain the result. In this case, the overall computational efficiency of the coupling solution algorithm may be many times higher than that of the decoupling solution algorithm. The solution algorithm can be selected according to actual conditions.
Specifically, the three-dimensional format of the NS equation for program calculation is derived, as shown in equation (24), equation (25), equation (26), and equation (27):
carrying out finite element dispersion on the three-dimensional format equation to obtain a formula (28), a formula (29) and a formula (30):
and solving a flow field equation of the coating die head according to the algorithm, and calculating the flow field condition of the corresponding non-Newtonian fluid by inputting the corresponding fluid viscosity under different shear rates. It should be noted that the above solving process may be implemented by a program, and when writing the flow field calculation program, the method may include the following steps:
firstly, declaring various function libraries required by the algorithm and defining global variables. In addition, a dynamic memory management method can be set to realize memory address allocation and deletion of variables. In addition, custom functions are set and program call interfaces are developed.
In the second step, the physical parameters of the coating liquid are set, for example, the name of the coating liquid is defined, the global coating liquid parameters are set, and the calculation function of the coating liquid parameters is declared. Meanwhile, aiming at each coating liquid, the coating liquid density, the Newtonian coating liquid viscosity, the non-Newtonian coating liquid viscosity and the coating liquid surface tension calculation function are matched.
And thirdly, outputting a simulation result. And reading mesh generation data by generating tetrahedral mesh generation of the regular area, and simulating in the mesh. In addition, the simulation error of each simulation step is calculated, and the output of the simulation result can be realized.
Fourthly, solving a standard finite element: the steps mainly realize the functions of finite element shape function construction, sparse matrix generation and management, linear algebraic equation system solution and the like.
Fifthly, dispersing an NS equation: the step part comprises three parts: solving for intermediate velocity fields, solving for pressure fields, and velocity field corrections.
Sixthly, primary side condition treatment: and applying boundary conditions of a speed field and a pressure field, reading initial flow field data, ensuring breakpoint continuous calculation capability, and recovering from abnormity and continuing calculation when abnormal conditions such as power failure occur.
The rheological property of the fluid is described by constructing a fluid rheological model, a coating die head flow field equation which meets the requirement is determined according to the coating process and the fluid property, and the non-Newtonian fluid is modeled by combining the fluid model and the coating die head flow field equation, so that the coating process of the non-Newtonian fluid can be simulated more truly, and the more accurate flow field condition is obtained.
Embodiments of the present specification further provide a flow field determination device based on a non-newtonian fluid, as shown in fig. 2, the device includes:
at least one processor; and the number of the first and second groups,
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor to enable the at least one processor to:
determining the corresponding fluid viscosity of the non-Newtonian fluid under different shear rates through a pre-constructed non-Newtonian fluid rheological model, wherein the non-Newtonian fluid rheological model is used for describing the corresponding relation between the viscosity and the shear rate of the non-Newtonian fluid; establishing an initial coating die head flow field equation in the coating process of the non-Newtonian fluid; determining initial conditions and boundary conditions of an initial coating die head flow field equation according to the characteristics of non-Newtonian fluid so as to determine the coating die head flow field equation meeting the requirements; and inputting the corresponding fluid viscosity under different shear rates into a coating die head flow field equation meeting the requirements, and determining the flow field of the non-Newtonian fluid.
Embodiments of the present specification also provide a non-volatile computer storage medium storing computer-executable instructions configured to: determining the corresponding fluid viscosity of the non-Newtonian fluid under different shear rates through a pre-constructed non-Newtonian fluid rheological model, wherein the non-Newtonian fluid rheological model is used for describing the corresponding relation between the viscosity and the shear rate of the non-Newtonian fluid; establishing an initial coating die head flow field equation in the coating process of the non-Newtonian fluid; determining initial conditions and boundary conditions of an initial coating die head flow field equation according to the characteristics of non-Newtonian fluid so as to determine the coating die head flow field equation meeting the requirements; and inputting the corresponding fluid viscosity under different shear rates into a coating die head flow field equation meeting the requirements, and determining the flow field of the non-Newtonian fluid.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the embodiments of the apparatus, the device, and the nonvolatile computer storage medium, since they are substantially similar to the embodiments of the method, the description is simple, and for the relevant points, reference may be made to the partial description of the embodiments of the method.
The foregoing description has been directed to specific embodiments of this disclosure. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
The above description is merely one or more embodiments of the present disclosure and is not intended to limit the present disclosure. Various modifications and alterations to one or more embodiments of the present description will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement or the like made within the spirit and principle of one or more embodiments of the present specification should be included in the scope of the claims of the present specification.
Claims (10)
1. A method for non-newtonian fluid based flow field determination, the method comprising:
determining corresponding fluid viscosity of the non-Newtonian fluid under different shear rates through a pre-constructed non-Newtonian fluid rheological model, wherein the non-Newtonian fluid rheological model is used for describing the corresponding relation between the fluid viscosity and the shear rate of the non-Newtonian fluid;
establishing an initial coating die head flow field equation in the coating process of the non-Newtonian fluid;
determining initial conditions and boundary conditions of the initial coating die head flow field equation according to the characteristics of the non-Newtonian fluid so as to determine the coating die head flow field equation meeting the requirements;
and inputting the corresponding fluid viscosity under different shear rates into the coating die head flow field equation meeting the requirements, and determining the flow field of the non-Newtonian fluid.
2. A method as claimed in claim 1, wherein before determining the corresponding fluid viscosities of the non-newtonian fluid at different shear rates through a pre-constructed non-newtonian fluid rheological model, the method further comprises:
acquiring fluid rheological property experimental curves of organic solute, organic solution and water under different conditions in advance;
and determining a non-Newtonian fluid rheological model according to the rheological property experimental curve and a plurality of preset rheological equations.
3. The method for determining a flow field based on a non-newtonian fluid according to claim 2, wherein the determining a rheological model of the non-newtonian fluid according to the rheological experimental curve and a plurality of preset rheological equations specifically includes:
dividing the fluid rheological property experimental curve into a plurality of curves according to a preset dividing mode;
fitting each curve with the multiple preset rheological equations respectively, calculating fitting errors of the multiple preset rheological equations on each curve, and selecting the preset rheological equation with the minimum fitting error as the rheological equation under the corresponding experimental condition of each curve;
and determining a plurality of rheological equations corresponding to the experimental curve of the fluid rheological property, and determining the plurality of rheological equations as the non-Newtonian fluid rheological model.
4. The method according to claim 1, wherein the determining initial conditions of the initial coating die flow field equation comprises:
setting initial conditions corresponding to the coating liquid state in the initial coating die head flow field equation and initial conditions corresponding to the coating process state;
wherein, the initial conditions corresponding to the liquid applying state comprise: setting the masking liquid to be incompressible fluid, setting the masking liquid to be isotropic fluid and setting the masking liquid to be single-phase fluid;
the initial conditions corresponding to the coating process state comprise that the coating process is set to be an isothermal process and the rheological law in the coating process is set to be constant.
5. A non-newtonian fluid based flow field determination method as claimed in claim 1, wherein the boundary conditions include: a boundary condition corresponding to an inlet boundary of the die head, a boundary condition corresponding to an outlet boundary of the die head, and a boundary condition corresponding to a solid wall boundary of the die head;
wherein the boundary condition of the inlet boundary of the die head is set as
U0In the form of an inlet velocity profile,
is the inlet volumetric flow rate;
the boundary condition of the outlet boundary of the die head is set as
p＝peU is the flow velocity, n is the flow velocity along the normal to the exit cross-section, peIs the ambient pressure;
the boundary condition of the solid wall boundary of the die head is set as
u·nw＝0，twIs a unit tangent vector at the position of the fixed wall,nwis the unit external normal vector at the fixed wall.
6. The method as claimed in claim 1, wherein the determining the flow field of the non-newtonian fluid comprises:
performing three-dimensional format conversion on the coating die head flow field equation according to a preset solving algorithm to obtain a plurality of corresponding three-dimensional format equations, wherein the type of the preset solving algorithm comprises a decoupling solving algorithm;
and carrying out finite element discretization on the three-dimensional format equation to obtain a corresponding discretization result so as to calculate the flow field of the non-Newtonian fluid according to the discretization result.
7. The non-newtonian fluid-based flow field determination method of claim 6, wherein when the type of the predetermined solution algorithm is a decoupling solution, the three-dimensional format conversion is performed on the coating die head flow field equations to obtain a plurality of corresponding three-dimensional format equations, specifically including:
decoupling the fluid velocity and the fluid pressure in the coating die head flow field equation to obtain an intermediate velocity expression and a pressure expression in the coating die head;
correcting the intermediate speed expression according to the pressure expression to obtain a speed correction expression;
and taking the intermediate speed expression, the pressure expression and the speed correction expression as a three-dimensional format equation.
8. The method for determining a flow field based on a non-newtonian fluid according to claim 7, wherein performing finite element discretization on the three-dimensional format equation to obtain a corresponding discretization result specifically comprises:
respectively carrying out finite element dispersion on the intermediate speed expression, the pressure expression and the speed correction expression, and determining an intermediate speed dispersion result, a pressure dispersion result and a correction speed dispersion result;
and calculating the intermediate speed dispersion result, the pressure dispersion result and the corrected speed dispersion result through a finite element dispersion algorithm to obtain the flow field of the non-Newtonian fluid.
9. A non-newtonian fluid based flow field determining apparatus, the apparatus comprising:
at least one processor; and the number of the first and second groups,
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor to enable the at least one processor to:
determining corresponding fluid viscosity of the non-Newtonian fluid under different shear rates through a pre-constructed non-Newtonian fluid rheological model, wherein the non-Newtonian fluid rheological model is used for describing the corresponding relation between the fluid viscosity and the shear rate of the non-Newtonian fluid;
establishing an initial coating die head flow field equation in the coating process of the non-Newtonian fluid;
determining initial conditions and boundary conditions of the initial coating die head flow field equation according to the characteristics of the non-Newtonian fluid so as to determine the coating die head flow field equation meeting the requirements;
and inputting the corresponding fluid viscosity under different shear rates into the flow field equation of the coating die head meeting the requirements, and determining the flow field of the non-Newtonian fluid.
10. A non-transitory computer storage medium storing computer-executable instructions configured to:
determining corresponding fluid viscosity of the non-Newtonian fluid under different shear rates through a pre-constructed non-Newtonian fluid rheological model, wherein the non-Newtonian fluid rheological model is used for describing the corresponding relation between the fluid viscosity and the shear rate of the non-Newtonian fluid;
establishing an initial coating die head flow field equation in the coating process of the non-Newtonian fluid;
determining initial conditions and boundary conditions of the initial coating die head flow field equation according to the characteristics of the non-Newtonian fluid so as to determine the coating die head flow field equation meeting the requirements;
and inputting the corresponding fluid viscosity under different shear rates into the flow field equation of the coating die head meeting the requirements, and determining the flow field of the non-Newtonian fluid.
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