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Problem with thin axisymmetric porous media

Question asked by Matthew Strangeway on May 2, 2016

I'm trying to model a filter made my wrapping a thin (0.008") sheet metal screen around a cylindrical frame. I'm approximating the screen and it's holes as an equally thin axisymmetric porous media and have a pressure drop that has pretty good agreement with what I see from the physical model. Because of the geometry of the holes in the screen, I would expect the streamlines as they cross the screen to be travelling mostly in the radial direction with little to no tangential velocity component. This is not the case, however, and the streamlines are mostly in the tangential direction. This is causing pressure gradients around the cylindrical frame on the filtrate side of the screen that I would not normally expect to see and is slightly concerning. I attached a picture showing the streamlines around a section of the screen. The screen is the light-blue, dotted line in the picture with the center of the cylinder it's wrapped around to the left of the picture. I guess my question is: is there something I can do with the porous media to force the streamlines to point more radially inward or is this just a necessary trade-off of using the porous media feature? Perhaps making the porous media thicker but calibrating it to have the same pressure drop? Thank you in advance for your response!