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-   -   also porosity setting (https://www.cfd-online.com/Forums/phoenics/51970-also-porosity-setting.html)

 billow November 12, 2005 08:24

also porosity setting

I'm confused with porosity setting such as VPOR and EPOR,ect.I have read Giorgio Crasto's messege at: http://www.cfd-online.com/Forum/phoenics.cgi?read=2532 but still not clear. I'm simulating a reactor filled with porous media which generates some kind of gas continuly. And I already added gas generation rate and DARCY resistance by PATCH-COVAL. I'm wondering if i should add porositys in the porous regin.(I have tried it and got a very diffrent result in pressure and velocity). If I should do it,how to do? the generation rate need to be converted by some way?

 mike November 14, 2005 07:35

Re: also porosity setting

If you solve for the superficial velocity, then you do not need to specify the volume porosity and area porosity vector. This is because their values are unity.

If you specify non-unity porosity values then you are actually solving for the "minimum-area" velocity, and so the resistance coefficient for the porous medium will differ from that used when solving for the superficial velocity.

 billow November 14, 2005 12:15

Re: also porosity setting

Thanks for your help, but how about the pressure? when I put in the porosity the velocity increased and the pressure be increased remarkably which I don't known why. (I think the pressue in Phoenics is 'static pressure' so it might be same with 'no porosity set' condition)

 mike November 16, 2005 07:26

Re: also porosity setting

If you are consistent when implementing each of the two different porous-media approaches, ie superficial and minimum-area, then the predicted pressure distribution should be the same. It is simplest to test this out in one dimension.

In general, it is best to use the superficial approach because this presents no problems at the junction of porous and non-porous materials, if these exist in the flow domain.

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