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Fluid flow in porous medium

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Old   February 5, 2020, 05:18
Default Fluid flow in porous medium
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Gokkul Raj
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Hello everyone

Currently, I am working in ANSYS Fluent with a porous medium. It is a 3D k-e model. I am having a doubt regarding the boundary conditions. I am specifying the porosity as well as Viscous and Inertial resistance. Is it fine to give the surface as a Wall for a porous medium? Because it seems to be in contrast with the definition of porous!

And is it possible to create an enclosure around the pipe and visualize the flow through the porous holes?

Thanks in advance!!
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Old   February 5, 2020, 06:54
Default BC for porous
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You may use pressure outlet as well. It won't change the solution much. There is usually a specific direction of the flow in the porous medium as well, it is alright to use lateral boundaries as walls as well. However, if the interest is in predicting the flow in multiple directions, then you have to use pressure outlet.

Fluent doesn't create any pores or holes. All the cells are open to the flow. Only the resistance is offered via source terms. You don't need to create a pipe or any other domain to visualize the flow. You may do it assuming porous domain is not porous; it's just another domain with a momentum sink.
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Old   February 5, 2020, 10:41
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Hello sir

I have tried giving the lateral boundaries as pressure outlets. I had got good results compared to giving it as a wall.

Now I am facing a problem, if I change the porosity, I am getting the same results for all porosities. Also, I am reducing the viscous resistance and inertial resistance of the order -3. Is this necessary to do?
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Old   February 5, 2020, 10:45
Default Porosity input does not affect the flow
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Porosity input has no effect on the predicted flow-field and the stress here is on input. Porosity affects the resistance coefficients and that's how it affects the flow. Otherwise, porosity is used only to determine superficial velocity. When other models, such as thermal energy, are involved, then porosity plays a significant role.
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boundary condition, enclosure, fluent, fluid flow, porous

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