plot formula for post processing

fjalil · July 7, 2010, 13:12

Hi,

I guess this is somwhere around the documentation I'm running against time, so I wanted to ask if anybody knows how to do this. I have to plot a fórmula along my domain in post processing.

The formula is

$I=\sqrt{0.5(u'^2+v'^2+w'^2)}/U$

Does anyone know the CEL names for these variables (u', v', w', U)?

I would really appreciate if someone could help me.

Francisca Jalil

ghorrocks · July 7, 2010, 20:09

You will have to define them as a variable in CFD-Post. If you used a two equation turbulence model then u', v' and w' will all be equal, and given by u'=sqrt(2*k/3) (see http://www.cfd-online.com/Wiki/Turbulence_intensity). If you used RSM they can be different, look up a turbulence textbook for the equations for that one.

If you used LES then are you talking about the resolved eddies or the sub-grid turbulence?

fjalil · July 7, 2010, 22:05

Thank you Glenn. I'm using a two equation turbulence model, so I guess it's the easy way. Thanks again!!

Francisca

ghorrocks · July 8, 2010, 09:34

Quote:

I'm using a two equation turbulence model, so I guess it's the easy way.

If you are using a 2-eqn model then it is the only way. There is no other way.

July 7, 2010, 13:12	plot formula for post processing	#1
fjalil New Member Francisca Join Date: Jun 2009 Posts: 14 Rep Power: 17	Hi, I guess this is somwhere around the documentation I'm running against time, so I wanted to ask if anybody knows how to do this. I have to plot a fórmula along my domain in post processing. The formula is $I=\sqrt{0.5(u'^2+v'^2+w'^2)}/U$ Does anyone know the CEL names for these variables (u', v', w', U)? I would really appreciate if someone could help me. Francisca Jalil

July 7, 2010, 22:05	Thanks!	#3
fjalil New Member Francisca Join Date: Jun 2009 Posts: 14 Rep Power: 17	Thank you Glenn. I'm using a two equation turbulence model, so I guess it's the easy way. Thanks again!! Francisca

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July 7, 2010, 20:09		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	You will have to define them as a variable in CFD-Post. If you used a two equation turbulence model then u', v' and w' will all be equal, and given by u'=sqrt(2*k/3) (see http://www.cfd-online.com/Wiki/Turbulence_intensity). If you used RSM they can be different, look up a turbulence textbook for the equations for that one. If you used LES then are you talking about the resolved eddies or the sub-grid turbulence?