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 Andy Chen December 28, 2009 09:49

turbulence model equation

Dear experts:

Turbulence model have one equation(turbulent energy model) that have dissipation term.Another, two equation(k-e model) that e was turbulence disspation transport equation. And, what about different on dissipation term and turbulence dissipation transport equation.

I studied paper. Everyone usually use one equation(turbulent energy model) to calculate turbulent energy dissipation budget. And FLOW-3D can output turbulence dissipation. But it seems different between on dissipation term and FLOW-3D output turbulence dissipation.

 MuxaB December 31, 2009 20:50

Quote:
 Originally Posted by Andy Chen (Post 241044) Dear experts: Turbulence model have one equation(turbulent energy model) that have dissipation term.Another, two equation(k-e model) that e was turbulence disspation transport equation. And, what about different on dissipation term and turbulence dissipation transport equation. I studied paper. Everyone usually use one equation(turbulent energy model) to calculate turbulent energy dissipation budget. And FLOW-3D can output turbulence dissipation. But it seems different between on dissipation term and FLOW-3D output turbulence dissipation. Thanks your help!
Hi,

What difference do you see between dissipation term in the turbulent energy equation and turbulent dissipation? They are the same, aint they?

 Andy Chen January 1, 2010 04:27

Quote:
 Originally Posted by mike@flow3d.com (Post 241211) Hi, What difference do you see between dissipation term in the turbulent energy equation and turbulent dissipation? They are the same, aint they?
I think that difference on unit. Beacuse the unit of dissipation term in one equation (turbulent energy equation) is [m^2/s^3] and the unit of turbulent transport dissipation (two eauations) is [kg/m/s^2]. Are they the same?

 MuxaB January 1, 2010 18:55

Quote:
 Originally Posted by Andy Chen (Post 241218) I think that difference on unit. Beacuse the unit of dissipation term in one equation (turbulent energy equation) is [m^2/s^3] and the unit of turbulent transport dissipation (two eauations) is [kg/m/s^2]. Are they the same? Thanks your reply mike!
The difference in your units is just density. Divide your turbulent transport dissipation by density and you have the same units. In any case, the two dissipations are the same quantities. In FLOW-3D turbulent dissipation has units of m^2/s^3.

 Andy Chen January 1, 2010 22:45

Quote:
 Originally Posted by mike@flow3d.com (Post 241248) The difference in your units is just density. Divide your turbulent transport dissipation by density and you have the same units. In any case, the two dissipations are the same quantities. In FLOW-3D turbulent dissipation has units of m^2/s^3.
Ok, I see. Thanks your help, Mike. :D

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