How to calculate the turbulence dissipation under the SAS-SST model in fluent?

- September 15, 2023 at 2:03 pm
  
  ztjia
  Subscriber
  
  when I use the SAS-SST model, I do not understand the epsilon(turbulence/turbulent dissipation rate epsilon). Does the "epsilon" represent the turbulent dissipation rate in SAS-SST model? I know that SAS-SST model can tranfer to the LES-like mode in the unsteady flow, so is the turbulent dissipation rate in SAS-SST model calculated by " effective viscosity*strain rate*strain rate"? hoe you can help me, thank you, waiting for your reply. Also, how to calculate the dissipation rate in the SBES model (k-omega SST)?
- September 20, 2023 at 6:16 pm
  
  Essence
  Ansys Employee
  
  Yes, epsilon is the turbulent dissipation rate. Please refer to the Ansys guide link:
  https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v232/en/flu_th/x1-1810005.20.2.html
  https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v232/en/flu_th/flu_th_sec_turb_scales_SBES.html?q=sbes
- September 21, 2023 at 6:42 am
  
  ztjia
  Subscriber
  
  sorry,the link I can not open
  - September 21, 2023 at 6:43 am
    
    ztjia
    Subscriber
    
    sorry, I can not open the link?is there any problem?
- September 21, 2023 at 8:13 am
  
  Rob
  Ansys Employee
  
  Click on Help in Fluent & paste the above into the browser that opens. Documentation is password protected but the solvers have a token/cookie/biscuit to bypass that step.
  - September 22, 2023 at 5:26 am
    
    ztjia
    Subscriber
    
    thanks for your reply. there still are some questions. for example, when I use SBES model based on the k-omega SST, how to calculate the subgrid viscosity? does the effective viscosity in fluent(Turbulence variable) include the subgrid viscosity? and under the SBES model, does S(strain rate tensor) represent the instantaneous velocity?

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