Hi,
I need to calculate the inertial and viscous resistance for porous material in Fluent.
After checking the Fluent manual, I picked the Ergun equation.
My question is how to find the values for 3-directions? If I used the same value, I'm assuming that my material is isotropic.
Is there any other ways to calculate these values by equations not experimental?
Ahmed,
If you assume that your material is isotropic, the values of the inertial and viscous resistance are the same in all directions.
You need experimental measurements of pressure drop + porosity to estimate these values.
Regards.
You need the void fraction of the bulk at any time (porosity variation). I think that you need a topologycal aproximation (the conection network o porosity) to calculate a model of pressure variation in three direction, before application of Ergun's equation.
Dear Ahmed
I hope this article helps you
7.19.6 User Inputs for Porous Media
When you are modeling a porous region, the only additional inputs for the problem setup are as follows. Optional inputs are indicated as such.
1. Define the porous zone.
2. Define the porous velocity formulation. (optional)
3. Identify the fluid material flowing through the porous medium.
4. Enable reactions for the porous zone, if appropriate, and select the reaction mechanism.
5. Enable the Relative Velocity Resistance Formulation. By default, this option is already enabled and takes the moving porous media into consideration (as described in Section 7.19.6).
6. Set the viscous resistance coefficients ( 📷 in Equation 7.19-1, or 📷 in Equation 7.19-2) and the inertial resistance coefficients ( 📷 in Equation 7.19-1, or 📷 in Equation 7.19-2), and define the direction vectors for which they apply. Alternatively, specify the coefficients for the power-law model.
7. Specify the porosity of the porous medium.
8. Select the material contained in the porous medium (required only for models that include heat transfer). Note that the specific heat capacity, 📷, for the selected material in the porous zone can only be entered as a constant value.
9. Set the volumetric heat generation rate in the solid portion of the porous medium (or any other sources, such as mass or momentum). (optional)
10. Set any fixed values for solution variables in the fluid region (optional).
11. Suppress the turbulent viscosity in the porous region, if appropriate.
12. Specify the rotation axis and/or zone motion, if relevant.
Methods for determining the resistance coefficients and/or permeability are presented below. If you choose to use the power-law approximation of the porous-media momentum source term, you will enter the coefficients 📷 and 📷 in Equation 7.19-3 instead of the resistance coefficients and flow direction.
You will set all parameters for the porous medium in the Fluid panel (Figure 7.19.1), which is opened from the Boundary Conditions panel (as described in Section 7.1.4).
Figure 7.19.1: The Fluid Panel for a Porous Zone 📷
Thank you all for your help.
Prof. Eman Kareem, may you provide the link for the article? it looks helpful.
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