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species transport: amg divergence

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Old   September 1, 2007, 11:32
Default species transport: amg divergence
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luke
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I'm modeling species transport where there is air in a volume at the bottom, and then connected to this volume are a few different channels with helium at different temperature. I have put in a polynomial diffusion coefficient (T dependent) so I want to see how the air diffuses up given that the different channels are at different tempeartures. I'm using nita but after about 100 iterations I get divergence in the amg solver: species. Does anyone have any recommendations on how to avoid this? I lowered all my relaxations to around 0.4 thanks in advance

luke
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Old   November 22, 2015, 14:40
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Farzaneh A
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maybe if you change the viscosity model, that be solved. I have the same problem (for a similar case) and when I changed my viscosity model and the boundary conditions, I've got no error
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Old   November 22, 2015, 15:25
Default divergence of temperature/species
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Farzaneh A
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Hi everybody
I'm modeling the plume of an industrial stack with fluent, to find the concentration of SO2 in a special distance of stack, and there are 9 components that coming out from the stack.
the temperature of stack is 141 degree of centigrade and the ambient temperature is 15 degree.
when I define just SO2 for the outlet of stack, the solution will be converge. but when I inter all of components, at final it's diverged and I see these messages:
divergence of temperature
divergence of species-1
divergence of species-2

could you help me please? I think I make a mistake in the definition of mixture that comes out from the stack.

Farzaneh
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