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-   -   Where's the turbulence and where is not? (http://www.cfd-online.com/Forums/main/2965-wheres-turbulence-where-not.html)

peter.zhao January 4, 2001 12:01

Where's the turbulence and where is not?
 
When I calculate a steady problem about a sphere ,including its wake,at supersonic perfect gas flow with Mach number 2.0,I am puzzled about how to judge where's turbulence so that the turbulent model takes effect.

All comments are welcomed!Thanks in advance.

John C. Chien January 4, 2001 14:32

Re: Where's the turbulence and where is not?
 
(1). What equations are you using? (2). If it is not in the equations, it is not going to show up in the results. (2). Turbulence can be in the freestream, in the wall boundary layer, and in the wake.

moomoo January 4, 2001 16:27

Re: I have some turbulence to spare
 
First I would suggest for you to define what turbulence is. Then It should become clearer where the regions of strong turbulence are...

ie. where are the regions of high fluctuating vorticity....

peter.zhao January 10, 2001 09:26

Re: Where's the turbulence and where is not?
 
I calculate N-S equation with B-L turbulance model for simplicity.It's well known the B-L model only modifies the viscous coefficient and the heat conduction coefficient with a premise that you should judge which region the B-L model takes effect.Some people judge the magnitude of viscous coefficient according to the experience and achieve succuss,but I don't know the detail of the implementation.

John C. Chien January 10, 2001 13:42

Re: Where's the turbulence and where is not?
 
(1). You can find the Baldwin-Lomax model and some discussions in the book "Turbulence Modeling for CFD" by David Wilcox. (2). For simple boundary layer flow, the model's F is a function of vorticity. For non-simple flows, this can be a source of problem. Anyway, the model was designed for simple boundary layer flows only, and it is a simple algebraic model.


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