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-   -   Calculation for Turbulent Length Scale (http://www.cfd-online.com/Forums/cfx/83052-calculation-turbulent-length-scale.html)

aqib December 13, 2010 07:07

Calculation for Turbulent Length Scale
 
Hello everyone,
I am using SST (Gamma-Theta) Model for the simulation of my Cascade T106A.
I have the problem regarding to set my Turbulent Length Scale value.
By Default it is 1. How should i select this value?
Any formula for that?
Does it effect on my results?
Give your opinion....
Regards:
Chishty

ghorrocks December 13, 2010 17:22

Set the incoming and/or initial turbulence levels to match the experiments you are reproducing. The default is just a guessed value to give it a default value.

If you do not have experimental turbulence levels then your experimental conditions are not fully defined.

aqib December 14, 2010 00:55

i am using FSTI=0.1 & 0.4
but can't specify the Turbulent Length Scale....
Any formula or theory for that, from where i can get that value....

ghorrocks December 14, 2010 05:50

As I now know you are using Fluent I can't tell you exactly which options to choose but I am sure Fluent has similar options to CFX. To get the equations to convert between turbulence intensity, energy, length scales etc get a decent turbulence textbook such as "Turbulence modelled for CFD" by Wilcox.

aqib December 14, 2010 06:24

ok i will read that book and come back to you soon....


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