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Eulerian Modeling: Frictional Viscosity Help

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Old   July 8, 2009, 14:46
Default Eulerian Modeling: Frictional Viscosity Help
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Casey
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Dear All,
I tried to make a UDF to mimic the frictional viscosity (Schaeffer) coded inside of fluent, but I was not able to do it. I know fluent sets a limit of 10^5 for the frictional viscosity, but I dont know how fluent deals with the frictional viscosity when the deviatoric strain rate is zero (since this is in the denominator or the frictional viscosity). I am simulating a bed of particles interacting with a jet of gas, so initially the particles aren't moving and I am having trouble with my UDF finding a way to properly limit the frictional viscosity. I tried using something where if deviatoric strain < 10^-12 then frictional viscosity = (Pf*sin(phi))/(solidsvof*10^-12). However, when I did this I still could not repeat the simulation results had found. Even with a higher limit on the frictional viscosity, the bed in my case was more liquid like than the fluent case.

Can anyone help? I have been banging my head against this problem for weeks. Let me know if you need more information.
Thanks,

casey

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