[godiex2]

I'm using ANSYS Fluent for some simulations in my dissertation. I wanted to ask about the energy equation used when running LES with incompressible fluid, no mixing or reaction. I found the energy equation listed in the ANSYS Fluent Theory Guide (in 5.2.1 Heat Transfer Theory) but I can't find the details about the turbulent thermal conductivity (k_t). Can anyone please link me to it if I missed it?

Is there a filtered form of the energy equation for LES in ANSYS Fluent? A link to that would be much appreciated.

[LuckyTran]

The turbulent conductivity you get from the turbulent Prandtl number which you can find as a setting. Specifically for LES though, this is the turbulent Prandtl number for the subgrid scales only since the filtered scales are resolved.

Of course a closure model has already been invoked. In general, it would be a turbulent heat flux which you can write other ways (not using turbulent conductivity). The filtered energy equation looks identical except you have filtered variables instead of normal variables and subgrid variables instead of turbulent variables, i.e. ksgs instead of kt. There is an ubiquitous notation clash here since ksgs is also the subgrid kinetic energy (instead of subgrid thermal conductivity).

[godiex2]

Originally Posted by LuckyTran

The turbulent conductivity you get from the turbulent Prandtl number which you can find as a setting. Specifically for LES though, this is the turbulent Prandtl number for the subgrid scales only since the filtered scales are resolved.

Of course a closure model has already been invoked. In general, it would be a turbulent heat flux which you can write other ways (not using turbulent conductivity). The filtered energy equation looks identical except you have filtered variables instead of normal variables and subgrid variables instead of turbulent variables, i.e. ksgs instead of kt. There is an ubiquitous notation clash here since ksgs is also the subgrid kinetic energy (instead of subgrid thermal conductivity).

Thank you for the response!
May I ask the relation between the effective Prandtl number and the turbulent Prandtl number?

[Golaselo]

Originally Posted by godiex2

Thank you for the response!
May I ask the relation between the effective Prandtl number and the turbulent Prandtl number?

Hello godiex, did you find out solution about turbulen heat flux?