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-   -   SA model in CFX (https://www.cfd-online.com/Forums/cfx/205688-sa-model-cfx.html)

lostking18 August 23, 2018 13:30

SA model in CFX
 
Hi, there

I am trying to use Spalart–Allmaras turbulence model in CFX but haven’t directly found it in the list of turbulence models. On the internet it seems to suggest that SA model is the ‘Eddy Viscosity Transport Equation Model’. But there is no official documents to state that. Moreover the paper that referred by ‘Eddy Viscosity Transport Equation Model’ is from Menter instead of Spalart and Allmaras. Could anyone tell me how can I implement SA model in CFX?

Thank you very much! ;)

karachun August 24, 2018 03:46

You can enable SA model by switching beta features ON.
https://www.cfd-online.com/Forums/cf...ce-models.html
https://imgur.com/LBiJlw3
https://imgur.com/ipH5Nlm

lostking18 August 26, 2018 06:40

Quote:

Originally Posted by karachun (Post 703767)

Hi, Karachun:

Thanks! And I also got some additional info from Ansys technicians about the boundary condition set-up of SA model:

The S-A-Model is still in Beta-Stadium in CFX.
The GUI is not consistent. For this particular boundary condition, the value of TI is simply ignored.

The other options require two values to calculate the turbulent viscosity nu_t at the inlet:
Intensity and Length Scale: nu_t = Cmu * sqrt(k) * length_scale, k = 1.5 * Intensity^2 * Velocity^2
k and epsilon: nu_t = Cmu * k^2 / epsilon
k and omega: nu_t = k / omega
k and Length Scale: nu_t = Cmu * sqrt(k) * length_scale

Hope this will also be helpful. ;)

karachun August 26, 2018 07:15

Thanks for reply!

modest_may September 6, 2018 20:35

Quote:

Originally Posted by lostking18 (Post 704000)
Hi, Karachun:

Thanks! And I also got some additional info from Ansys technicians about the boundary condition set-up of SA model:

The S-A-Model is still in Beta-Stadium in CFX.
The GUI is not consistent. For this particular boundary condition, the value of TI is simply ignored.

The other options require two values to calculate the turbulent viscosity nu_t at the inlet:
Intensity and Length Scale: nu_t = Cmu * sqrt(k) * length_scale, k = 1.5 * Intensity^2 * Velocity^2
k and epsilon: nu_t = Cmu * k^2 / epsilon
k and omega: nu_t = k / omega
k and Length Scale: nu_t = Cmu * sqrt(k) * length_scale

Hope this will also be helpful. ;)

Thank you for your kind and helpful message.
Do you know the requirement for the yplus value near the wall? Should the yplus be smaller than 1? There are two options, including default and scalable, for the wall function term.


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