transition onset - SST:Gamma Theta Model

February 6, 2007, 02:52

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

February 8, 2007, 13:34

Inlet turbulence influences transition onset to a very large extent, at least for Langtry Menter.

February 20, 2007, 10:47

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

February 21, 2007, 06:24

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

February 21, 2007, 09:32

Prad,

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

Thanks

Adam

February 6, 2007, 02:52	transition onset - SST:Gamma Theta Model	#1
Prad Guest Posts: n/a	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

February 8, 2007, 13:34	Re: transition onset - SST:Gamma Theta Model	#2
Chebeba Guest Posts: n/a	Inlet turbulence influences transition onset to a very large extent, at least for Langtry Menter.

February 20, 2007, 10:47	Re: transition onset - SST:Gamma Theta Model	#3
Adam Guest Posts: n/a	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

February 21, 2007, 06:24	Re: transition onset - SST:Gamma Theta Model	#4
Prad Guest Posts: n/a	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

February 21, 2007, 09:32	Re: transition onset - SST:Gamma Theta Model	#5
Adam Guest Posts: n/a	Prad, Not sure what you mean. Could you please give me more information before I can help you. Thanks Adam

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