## Fluids

#### Total Turb. Kinetic Energy and Dissipation Rate

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• NimaNZ
Subscriber

Hi everyone

As in LES the TKE and TDR are not provided I have to calculate them through the CFF for the sampling process.

I can calculate the resolved TKE by: (rmse-x-velocity ^ 2 + rmse-y-velocity ^ 2 + rmse-z-velocity ^ 2) / 2

But how can I calculate the modeled TKE in the WALE SGS model to obtain the total TKE as TKE_tot=TKE_resolved+TKE_modeled

And how about the TDR?

I want these two values for obtaining the Lenght Scale of Turbulence as L=(K^3/2)/epsilon

I would appreciate any help or suggestion.

Thanks

• DrAmine
Ansys Employee
TKE modeled can be estimated from
S is the strain rate magnitude.

TDR is proportional to S^2. Proportionality constant is mu+mu_t.
• NimaNZ
Subscriber

Thanks a million for your reply. Can I calculate it through the following If so, is l_sgs the Ls in the ANSYS formulation? which is the following in the WALE model. And is the length scale of turbulence that I need for grid resolution assessment as L/delta?
*EDITED by DrAmine: Removed Picture*

• DrAmine
Ansys Employee
What about just using the formula I posted to be independent from the length scale (sma constant * cube root of volume the default is 0.1 and 0.325 for wale)? I will remove the picture from the help you are referring to. The length should be the
• NimaNZ
Subscriber
Sure, if I use that formula, should I add the CFF for sampling? or I can use the results of default sampling variables?
• DrAmine
Ansys Employee
Yes to get the time average value. Unsteady statistics are anyhow required to get the RMSE to build-up the resolved part.
• NimaNZ
Subscriber
Thanks a million
• DrAmine
Ansys Employee
You want to give me a million :) ?
• NimaNZ
Subscriber
well if I get this project published, why not? :))
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