# Define Porous media by Volume Selection

#1

The following feature is something that is often done in the filtration industry.

I would like the ability to define porous media by an imported volume. In the project attached you will see I have 2 volumes one for the flow domain and one for the porous medium (air filter). Currently all we can do is define a porous media by geometry primitive. This will not work for a cylindrical air filter where the flow moves radially. As shown in the picture the flow would come in from the inlet into the inner diameter of the filter. The flow would then move radially through the porous media and finally around the outside diameter of the filter to the outlet.

Here is a project example of this geometry: https://www.simscale.com/workbench?publiclink=70955638-8a78-43a6-bd91-a5cb4642aef5

I would use solid_1 as the flow domain and solid_0 as the selection for porous media instead of a geometry primitive. Note: solid_0 is overlapping solid_1.

In the end I would need to be able to also define the porous media resistance in a cylindrical coordinate system. Where I could define resistance in the radial, axial, and tangential directions. Can this be done currently? Or, would this be another feature to vote for?

Thanks,
Eric

#2

Hi @eweber !

I cant really understand where is you filter zone should be. Could you please specify it in more details?

And previuos topic on porosity definition is here, probably you can find useful info here:

#3

The picture that I have shown in my initial post shows the airflow pattern of a cross section. The model is axisymmetric and I am showing a cut down the middle. This is a cylindrical filter where air flows in from the inlet and into the inside of a cylindrical filter then the air moves radially out through the filter. In the picture the porous media is red.

Here is a picture of a real life example. The filter seals on the endcaps.

https://www.donaldson.com/en-us/engine/filters/articles/keep-running-with-donaldson/

Does that explanation help?

-Eric

#4

Hi @eweber,

I finnaly understood the idea of your project. It seems like OpenFOAM in general is capable for solvins such a roblems - https://www.cfd-online.com/Forums/openfoam-pre-processing/61982-porous-case.html
and the final part here - https://github.com/OpenFOAM/OpenFOAM-4.x/blob/master/etc/caseDicts/general/fvOptions/porosity/porousZone

But there is no such an option in Simsclae right now unfortunatly.

The best thin you can do in this sitiation in set up the case in Simscale manually with usual porouse system coordinate system, donwload this case and edit settings manually according to OpenFOAM manual for cylindrical porosity and run it (again, locally).

Best regards,
Eugeny.

#5

I would like to use a porous media to simulate perforation. CADing and meshing perforated shapes is CPU costly, and it usually fails.

Is there any movement to include porous media shapes in Simscale?

If I download open foam can I model complex porous media shape, not just simple shapes?

Can I create a custom boundary condition in Simscale that has flow based on normal velocity to the surface?

#6

Hi @dhamilton!

Several things that might help you out here:

For the last link that I mentioned, please not that there might be changed involved that are not covered in the post. Let us know if that’s something you were looking for.

Jousef