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Density problems

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Old   February 22, 2002, 04:48
Default Density problems
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Hi, I have a huge problem where I use an user defined density (densit.f) density=f(T), because in my case I get the density (and temperature) from a PDF. But as soon as the density starts to vary (very small variation in the beginning), I get oscillations in the pressure field and hence the velocity field, especially near my outlet (standard). I use a pseudo transient solution. I will appreciate any help. Regards, Ulf
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Old   February 24, 2002, 23:32
Default Re: Density problems
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Pressure equation is basically derived from the continuity equation. In each iteration, p and v will be corrected for mass conservation. If you changed density, p and v should reflect the change. I think that is why in StarCD, a density equation will be solved for compressible flow in order to resolve conservation. If you gave a flow rate either thru inlet or outlet B.C. definition, and then you changed density in the field, I wonder if mass conservation can be satisfied. So, I would suggest checking your flow field if you artificially generated mass source or sink.
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