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-   -   Porosity profile, dividing a zone, or getting zone location from zone (http://www.cfd-online.com/Forums/fluent/102802-porosity-profile-dividing-zone-getting-zone-location-zone.html)

 khoopes June 2, 2012 19:39

Porosity profile, dividing a zone, or getting zone location from zone

For some research that I am doing, I am trying to model the flow through a screen. I have been using the porous media model in fluent and have been getting some good results. The idea is to generate a desired total pressure profile by changing the porosity in different locations of a screen. So far the shape of my profile looks very close to what I have been getting experimentally. I just need to do some more experiments so that I can get the Alpha and C2 parameters that fluent needs and have them be relatable to reality.

So far all of this work has been done on a 2D model. Basically a rectangle with a line down the center in the transverse direction for the porous-jump condition. One thing that I am doing is coupling FLUENT with Matlab so that I can have it iterate on the porosity at different locations to match the desired exit total pressure profile. This is working surprisingly well in 2D. I have Matlab scripted so it will generate the FLUENT code to take a start Fluent case, and then cut up the porous-jump zone into a set number of equally spaced zones and apply a given porosity to each. Then FLUENT solves and passes the resulting profile back to Matlab which then adjusts the porosities and tries again. The way that I have been doing this is using an adaptation register to mark the area I want to cut from the starting porous-jump zone and then use the split zone command to do the cutting. I just keep track of what the BC id number is and set the porosity. Like I said it is working really well.

I am now trying to move to a 3D case with a 2D porous-jump. I think this same method will work, but my problem will be that I think that I will only be able to select rectangular areas of my 2D screen to apply different porosities to. I would rather be able to select any geometry and not be limited to rectangles. I know there is a split zone by faces command that will split a zone by the cells faces that make it up, but I am not sure then how to specify the porosity as I will not know which new zone is where.

Maybe I am thinking about this problem wrong, but what I am looking for is a way to specify different porosities in different areas of zone (probably by dividing that zone) and not be limited to rectangular divisions.

If there was a way that I could get the x,y,z location of a zone after I split a zone into its faces that would be enough. I would just end up with the same number of zones as I have cells with faces on the starting zone, but that would work. It is frustrating because I can do it with the mouse, if I select a zone it will tell me the zone-id, but I cannot seem to find a way that I can, through the command line interface, get the x,y,z location of a zone just by knowing its ID.

The best way would be to be able to define an alpha or C2 profile like I can for a velocity profile, but I am not sure the porous jump model supports it.

Any help would be appreciated of if you do not fully get what I am saying let me know and I can try to explain it again.