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UDS Diffusivity in porous media

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Old   November 6, 2013, 10:21
Default UDS Diffusivity in porous media
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Tom Tranter
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Hi,

I'm trying to simulate conduction through porous media with an electric potential. I've set up the potential as a UDS and I have materials with UDS diffusivity defined to represent the electric conductivity. As far as I can tell from previous posts the UDS diffusivity is not automatically multiplied by the porosity and volume averaged between the materials like the thermal conductivity is when solving the energy equation.

My question is how do I access the solid material properties, specifically the UDS diffusivity, of the porous media in a UDF so that I can manually adjust the value to generate an effective conductivity in each porous zone?

Thanks
Tom
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Old   November 7, 2013, 09:26
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Tom Tranter
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Please can anyone point me in the right direction here. I need UDSI_DIFF for the solid part of a porous zone basically. I cannot find any reference in the manual or variations of UDSI_DIFF in mem.h
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Old   February 13, 2014, 07:21
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A-A Azarafza
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Hi Friend,
You need to define diffusivity for each of the UDS using user-defined diffusivity macro. To calculate effective diffusivity, you can invoke the porosity using C_POR(c,t) macro for each of the cells in the zones you want to set effective porosity. I mean, for instance, if you want to use Bruggeman model as effective diffusivity, first, define diffusivity using DEFINE_DIFFUSIVITY (If I'm not wrong) for each zone and then multiply it by C_POR (c,t) macro. I hope it helps
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