Training Guide > Porous Media Flow Tutorials > Isotropic Porous Media Tutorial > Specifying Porosity Coefficients
Specifying Porosity Coefficients
As discussed in the introduction to this tutorial, the porous region is defined by its inertial and viscous resistance coefficients, which are 25 kg/m4 and 1500 kg/m3s, respectively. As the porous region is isotropic, these values hold in all directions. The coefficients, along with the turbulence parameters in the porous region, must now be specified.
To start with, the Porous region must be defined as a porous medium.
- Select the Porous node under the Regions node and, in the Properties window, change the Type property to .
- Select the Porous > Physics Conditions > Turbulence Specification node
- Change the Method property to
- Select the Physics Values > Porous Inertial Resistance node.
In the Properties window, note that the Method property is, by default, set to . This is suitable because the constant resistance coefficients correspond to the principal (diagonal) components of the porous resistance tensor.
- Select the Porous Inertial Resistance > Principal Tensor > XX Component > Constant node and change the Value property to
25 kg/m4.
- Similarly, set the Value properties for the YY Component > Constant and ZZ Component > Constant to
25 kg/m4 also
.
The XX Axis and YY Axis do not need to be changed because the porous resistance components are specified in the directions of the default axes.
- Open the Porous Viscous Resistance > Principal Tensor node.
- Using the same method as for the inertial resistance, specify each of the three components of the viscous resistance to be 1500 kg/m3-s.
- Select the Turbulence Intensity node and change the Value property to
0.1.
The default turbulent length scale of 0.01 m is suitable for this case so it does not need changing.
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