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-   -   transition onset - SST:Gamma Theta Model (http://www.cfd-online.com/Forums/cfx/23616-transition-onset-sst-gamma-theta-model.html)

Prad February 6, 2007 03:52

transition onset - SST:Gamma Theta Model
 
Hi, am having problems with ascertaining my

TRANSITION ONSET CORRELATION: Option = User Defined Transition Onset Reynolds Number = 260.0*(1.0+x/(1.0[m]))

Cant seem to figure out what happens when I change values. Maybe I've overlooked some thing. I've tried variations but they're all larger by approx. factor 2 when compared with my experimental (Ca vs. Cw plots for various angles)data. What is the influence of inlet conditions (eddy viscosity etc)? Other approaches (Langtry Menter) do not bring better results. There's very little background available. Maybe someone here works with tra- onset regularly. Any suggestions are welcome. Gracias Prad

Chebeba February 8, 2007 14:34

Re: transition onset - SST:Gamma Theta Model
 
Inlet turbulence influences transition onset to a very large extent, at least for Langtry Menter.

Adam February 20, 2007 11:47

Re: transition onset - SST:Gamma Theta Model
 
Sensitivity to inlet conditions are indicitave of the gamma theta model structure in general. Mostly Tu and viscosity ratio.

What are you modelling and how, what is your grid stats, where did you get your correlation for retheta?

Adam

Prad February 21, 2007 07:24

Re: transition onset - SST:Gamma Theta Model
 
Hi Adam, have an Eppler profile, all boundaries are 4~5x distant from the foil (2cells deep), y+ around 1, have now switched all values to default values. Drag is influencing my polar which is straying from experimental values.Thanks for further info Prad

Adam February 21, 2007 10:32

Re: transition onset - SST:Gamma Theta Model
 
Prad,

Not sure what you mean. Could you please give me more information before I can help you.

Thanks

Adam


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