Thanks for you hint JMirisola!
FYI, I used the appearance feature to make the element(filter)meshed, this creates porous on the surface although you have no control over the sizes (40 microns in my case), but it roughly did the job,
Another question: the object(a chamber with a filter inside) is ready for the flow simulation, you should close the inlet and outlet as SW prompts you by putting "lids", I did so but it keeps giving the error saying: "The selected face dose not contact fluid or it is an external face of the model"
I changed the lids but still doesn't proceed the flow running to the chamber,
Any idea?
Thanks alot