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Old   March 28, 2010, 19:15
Default reynolds shear stress
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lorenzo.iovio
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How can I build a scalar scene for the Reynolds shear stress?I have to select some in the physics model?or something else?
In the field functions this stress doesn't appear!!!
I am using k-epsilon model or k-omega model for the turbolence!
Thanks to all!
Lorenzo
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Old   March 29, 2010, 13:48
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Pete Launie
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I think you have to write your own unless the RST model is activated. At least that's what I had to do.

here is what I had in 2D, it was supposed to give me a vector: RS[ii],RS[jj],RS[ij] but the last term [ij] is wrong as I wasn't sure how to get du/dy, or dv/dx (simply). I abandoned it as I had other more pressing things to work on.

[
2*$TurbulentViscosity*(grad(mag($$Velocity))[1])-(2/3)*$Density*$TurbulentKineticEnergy,

2*$TurbulentViscosity*(grad(mag($$Velocity))[2])-(2/3)*$Density*$TurbulentKineticEnergy,

2*$TurbulentViscosity*(grad(mag($$Velocity))[3])]


it came from http://www.cfd-online.com/Wiki/Bouss...ity_assumption
with StarCCM defining the strain rate tensor in eqn [306] (Search StarCCM Help)

If you come up with an answer though it would be helpful.
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Old   July 8, 2010, 16:25
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Joshua Counsil
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Can't you just multiply the velocity correlations, e.g., uu, by the density? The velocity correlations are directly extractable from CFX-Post.
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