Air flow through a porous medium
 

Hey guys,

I'd like to ask your help. I'm trying to simulate an airflow through a porous medium. I just have the following information about this medium: it's a nylon filter of porosity 0.49.

It's used at the exit of a wind tunnel to control the pressure inside it. I don't know the pressure drop across the filter.

Is there any way of modeling it just knowing the porosity?

Thank you in advance,

Matheus.

Well, yes and no.

Yes, you can model it only with the porosity, but one of the things needed by a porous domain is the information on how much losses it will input in your flow. So if you don't have that, you won't be able to tell if your results are correct. In other words, your domain won't put a pressure loss in your flow, which is very likely incorrect.

You can either try to search the internet for information close to what you want to model or you can try to infer the pressure loss from mass flow and velocity magnitude. But without any data about how it works in reality it you won't be able to validate your simulation.

If you have nothing else to go by then assume it is made up of little orifaces of regular size. You choose a size which is representative of the pore size in the membrane. You can work out an approximate pressure drop from the oriface plate equation. Very approximate but better than nothing.