fluent中多孔介质设置问题和算例文档格式.docx

1、打开grid图，看看X,Y,Z的方向，如果是X向，矢量为1,0,0,同理Y向为0,1,0，Z向为0,0,1,如果所需要的方向与坐标轴正向相反，则定义矢量为负）圆锥坐标与球坐标请参考fluent帮助。2）定义粘性阻力1/a与内部阻力C2：请参看本人上一篇博文“终于搞清fluent中多孔粘性阻力与内部阻力的计算方法”，此处不赘述；3）如果了定义粘性阻力1/a与内部阻力C2,就不用定义C1与C0，因为这是两种不同的定义方法，C1与C0只在幂率模型中出现，该处保持默认就行了；4）定义孔隙率porousity，默认值1表示全开放，此值按实验测值填写即可。完了，其他设置与普通k-e或RSM相同。总结一下，

2、与君共享!Tutorial 7. Modeling Flow Through Porous MediaIntroductionMany industrial applications involve the modeling of flow through porous media, such as filters, catalyst beds, and packing. This tutorial illustrates how to set up and solve a problem involving gas flow through porous media.The industri

3、al problem solved here involves gas flow through a catalytic converter. Catalytic converters are commonly used to purify emissions from gasoline and diesel engines by converting environmentally hazardous exhaust emissions to acceptable substances.Examples of such emissions include carbon monoxide （C

4、O）, nitrogen oxides （NOx）, and unburned hydrocarbon fuels. These exhaust gas emissions are forced through a substrate, which is a ceramic structure coated with a metal catalyst such as platinum or palladium.The nature of the exhaust gas flow is a very important factor in determining the performance

5、of the catalytic converter. Of particular importance is the pressure gradient and velocity distribution through the substrate. Hence CFD analysis is used to design efficient catalytic converters: by modeling the exhaust gas flow, the pressure drop and the uniformity of flow through the substrate can

6、 be determined. In this tutorial, FLUENT is used to model the flow of nitrogen gas through a catalytic converter geometry, so that the flow field structure may be analyzed.This tutorial demonstrates how to do the following:_ Set up a porous zone for the substrate with appropriate resistances._ Calcu

7、late a solution for gas flow through the catalytic converter using the pressure based solver._ Plot pressure and velocity distribution on specified planes of the geometry._ Determine the pressure drop through the substrate and the degree of non-uniformity of flow through cross sections of the geomet

8、ry using X-Y plots and numerical reports.Problem DescriptionThe catalytic converter modeled here is shown in Figure 7.1. The nitrogen flows in through the inlet with a uniform velocity of 22.6 m/s, passes through a ceramic monolith substrate with square shaped channels, and then exits through the ou

9、tlet.While the flow in the inlet and outlet sections is turbulent, the flow through the substrate is laminar and is characterized by inertial and viscous loss coefficients in the flow （X） direction. The substrate is impermeable in other directions, which is modeled using loss coefficients whose valu

10、es are three orders of magnitude higher than in the X direction.Setup and SolutionStep 1: Grid1. Read the mesh file （catalytic converter.msh）.File /Read /Case.2. Check the grid. Grid /CheckFLUENT will perform various checks on the mesh and report the progress in the console. Make sure that the minim

11、um volume reported is a positive number.3. Scale the grid.Grid! Scale. （a） Select mm from the Grid Was Created In drop-down list.（b） Click the Change Length Units button. All dimensions will now be shown in millimeters.（c） Click Scale and close the Scale Grid panel.4. Display the mesh. Display /Grid

12、.（a） Make sure that inlet, outlet, substrate-wall, and wall are selected in the Surfaces selection list.（b） Click Display.（c） Rotate the view and zoom in to get the display shown in Figure 7.2.（d） Close the Grid Display panel.The hex mesh on the geometry contains a total of 34,580 cells.Step 2: Mode

13、ls1. Retain the default solver settings. Define /Models /Solver.2. Select the standard k- turbulence model. Define/ Models /Viscous.Step 3: Materials1. Add nitrogen to the list of fluid materials by copying it from the Fluent Database for materials. Define /Materials.（a） Click the Fluent Database. b

14、utton to open the Fluent Database Materials panel.i. Select nitrogen （n2） from the list of Fluent Fluid Materials.ii. Click Copy to copy the information for nitrogen to your list of fluid materials.iii. Close the Fluent Database Materials panel.（b） Close the Materials panel.Step 4: Boundary Conditio

15、ns. Define /Boundary Conditions.1. Set the boundary conditions for the fluid （fluid）.（a） Select nitrogen from the Material Name drop-down list.（b） Click OK to close the Fluid panel.2. Set the boundary conditions for the substrate （substrate）.（b） Enable the Porous Zone option to activate the porous z

16、one model.（c） Enable the Laminar Zone option to solve the flow in the porous zone without turbulence.（d） Click the Porous Zone tab.i. Make sure that the principal direction vectors are set as shown in Table7.1. Use the scroll bar to access the fields that are not initially visible in the panel.ii. E

17、nter the values in Table 7.2 for the Viscous Resistance and Inertial Resistance. Scroll down to access the fields that are not initially visible in the panel.（e） Click OK to close the Fluid panel.3. Set the velocity and turbulence boundary conditions at the inlet （inlet）.（a） Enter 22.6 m/s for the V

18、elocity Magnitude.（b） Select Intensity and Hydraulic Diameter from the Specification Method dropdown list in the Turbulence group box.（c） Retain the default value of 10% for the Turbulent Intensity.（d） Enter 42 mm for the Hydraulic Diameter.（e） Click OK to close the Velocity Inlet panel.4. Set the b

19、oundary conditions at the outlet （outlet）.（a） Retain the default setting of 0 for Gauge Pressure.（c） Enter 5% for the Backflow Turbulent Intensity.（d） Enter 42 mm for the Backflow Hydraulic Diameter.（e） Click OK to close the Pressure Outlet panel.5. Retain the default boundary conditions for the wal

20、ls （substrate-wall and wall） and close the Boundary Conditions panel.Step 5: Solution1. Set the solution parameters. Solve /Controls /Solution.（a） Retain the default settings for Under-Relaxation Factors.（b） Select Second Order Upwind from the Momentum drop-down list in the Discretization group box.

21、（c） Click OK to close the Solution Controls panel.2. Enable the plotting of residuals during the calculation. Solve/Monitors /Residual.（a） Enable Plot in the Options group box.（b） Click OK to close the Residual Monitors panel.3. Enable the plotting of the mass flow rate at the outlet.Solve / Monitor

22、s /Surface.（a） Set the Surface Monitors to 1.（b） Enable the Plot and Write options for monitor-1, and click the Define. button to open the Define Surface Monitor panel.i. Select Mass Flow Rate from the Report Type drop-down list.ii. Select outlet from the Surfaces selection list.iii. Click OK to clo

23、se the Define Surface Monitors panel.（c） Click OK to close the Surface Monitors panel.4. Initialize the solution from the inlet. Solve /Initialize /Initialize.（a） Select inlet from the Compute From drop-down list.（b） Click Init and close the Solution Initialization panel.5. Save the case file （catal

24、ytic converter.cas）. File /Write /Case.6. Run the calculation by requesting 100 iterations. Solve /Iterate.（a） Enter 100 for the Number of Iterations.（b） Click Iterate.The FLUENT calculation will converge in approximately 70 iterations. By this point the mass flow rate monitor has attended out, as s

25、een in Figure 7.3.（c） Close the Iterate panel.7. Save the case and data files （catalytic converter.cas and catalytic converter.dat）.File /Write /Case & Data.Note: If you choose a file name that already exists in the current folder, FLUENTwill prompt you for confirmation to overwrite the file.Step 6:

26、 Post-processing1. Create a surface passing through the centerline for post-processing purposes.Surface/Iso-Surface.（a） Select Grid. and Y-Coordinate from the Surface of Constant drop-down lists.（b） Click Compute to calculate the Min and Max values.（c） Retain the default value of 0 for the Iso-Value

27、s.（d） Enter y=0 for the New Surface Name.（e） Click Create.2. Create cross-sectional surfaces at locations on either side of the substrate, as well as at its center. Surface /Iso-Surface.（a） Select Grid. and X-Coordinate from the Surface of Constant drop-down lists.（c） Enter 95 for Iso-Values.（d） Enter x=95 for the New Surface Name.（f） In a similar manner, create surfaces nam