How to obtain the SGS turbulent kinetic energy in LES model

GaryPei · June 3, 2020, 21:11

Dear Experts,

I am using the LES model to simulate the room airflow on StarCCM+. I would like to compare the contour of total turbulent kinetic energy to the RANS model.

I am aware that the total turbulent kinetic energy of LES has resolved and SGS parts. Now I can calculate the resolved part using field variance (thanks to this forum). But I still don't know how to obtain the SGS turbulent kinetic energy (after searching the forum).

I used the WALE SGS model and seems there is no built-in function for this. I tried to create the new field function but I had difficulty defining this value. The equations in guidebook shows the SGS Tke is the function of strain rate tensor. I have no clue how to define it as field function.

Please let me know if you have any advice. Thank you.

Regards,
Gen Pei

LuckyTran · June 4, 2020, 06:17

If you enable temporary storage retained then the modulus of the strain rate tensor will be available as a field function which is all you need.

The strain rate tensor, being a tensor, is somewhat tricky to define using only vector field functions.

theindianlel · May 30, 2023, 05:23

You can activate aeroacoustics model(even if you are not going to use it) to get the in-built SGS Turbulent Kinetic Energy variable.

June 3, 2020, 21:11	How to obtain the SGS turbulent kinetic energy in LES model	#1
GaryPei New Member gen pei Join Date: Aug 2019 Posts: 10 Rep Power: 6	Dear Experts, I am using the LES model to simulate the room airflow on StarCCM+. I would like to compare the contour of total turbulent kinetic energy to the RANS model. I am aware that the total turbulent kinetic energy of LES has resolved and SGS parts. Now I can calculate the resolved part using field variance (thanks to this forum). But I still don't know how to obtain the SGS turbulent kinetic energy (after searching the forum). I used the WALE SGS model and seems there is no built-in function for this. I tried to create the new field function but I had difficulty defining this value. The equations in guidebook shows the SGS Tke is the function of strain rate tensor. I have no clue how to define it as field function. Please let me know if you have any advice. Thank you. Regards, Gen Pei

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June 4, 2020, 06:17		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,490 Rep Power: 64	If you enable temporary storage retained then the modulus of the strain rate tensor will be available as a field function which is all you need. The strain rate tensor, being a tensor, is somewhat tricky to define using only vector field functions.

May 30, 2023, 05:23		#3
theindianlel New Member TheIndianLel Join Date: Mar 2019 Posts: 24 Rep Power: 6	You can activate aeroacoustics model(even if you are not going to use it) to get the in-built SGS Turbulent Kinetic Energy variable.