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QUESTIONS about Coupled Implicit

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Old   March 6, 2005, 22:05
Default QUESTIONS about Coupled Implicit
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Hi Everyone,

I just had some general questions about the coupled implicit solver:

1. Is it okay if your final run has a second order flow, but a first order turbulence model? (Once I turn on the second order upwind for the standard k-e...a lot of weird stuff turbulent viscosity goes very high, then temperature and pressure goes too high, residuals start diverging and levels out constantly, eventually whenever there is adaption, the solution diverges and kills itself. )

2. i am running a cold nitrogen gas flow through a supersonic nozzle and I want to see the pressure impingements on a flat plate. I get really good convergence when i run a second order flow but a first order turbulence model. is this okay??

3. when should i turn on the second order turbulence model? Can i turn it on after the mass imbalance is close to zero?

4. What equation should i use to determine the turbulent viscosity ratio? I know that it is laminar viscosity/turbulent viscosity.

5. i got really high turbulent viscosity ratio cells, but i do not know how to get rid of them. is it because my elements are too skewed?

hope to hear from you soon. thank you. regards, manish
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