I have been working on a flow simulation of an air system which has a couple of HEPA filters and a blower. I have flow rate and pressure drop from the filter supplier and a blower curve. When I asked the filter supplier for the porosity of the filter they told me that it was N/A, however any setting I try to use for the filter within the porous media features require me to enter porosity. I havent been able to find this information anywehere else either, so I have set the porosity at 0.3 as a best guess.
The filter has a spec of 510 CFM at 0.40" H20 and the blower has a rate of 475 CFM at 0.78" H20. Since I have two filters I expect the flow through the filter should be laminar, but the simulation shows that flow is uneven and almost in a vortex.
Is there another way to set up a porous material that does not require entering a porosity?
From what I have read there is no direct correlation between micron size and porosity; is there any other way to link these properties?