Learning Forum

[Pritesh Ramya]

Hello!

I have been trying to simulate flow past a cylinder with Re = 26700 using three turbulence models, namely, k-w SST, k-e realizable with enhanced wall treatment (henceforth referred to as KEEWT) and Spalart-Allmaras. Now in the past versions of Fluent, I have seen that k-w SST and Spalart-Allmaras had Low-Re correction and Low Re damping options respectively (I assume they serve the same purpose). Given that my maximum y+ is approximately equal to 0.6, I wanted to switch this functionality on for my k-w SST and Spalart-Allmaras runs. I was able to do it for k-w SST but I could not find the option for Spalart-Allmaras in the version of Fluent I am using, i.e., 2022 R2. I have gone through the user guide and there is no mention of the absence of this feature. Does it mean that you guys have removed the option, given that it is a low-Re turbulence model?

Thank you.

[Federico Alzamora Previtali]

Hello Pritesh,

in which earlier versions of Fluent have you seen this Low-Re Damping for Spalart-Allmaras? I must say that I have not seen this in my time here but if you know the version, I could point to the documentation with release notes if/when this option was removed.

[Pritesh Ramya]

Hello Federico!

Thank you for your response.

I must confess I am not aware of the exact version number. However, while I was searching for Low-Re correction/damping option for the Spalart-Allmaras turbulence model, I was directed to the following ANSYS website.

https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node435.htm

https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node423.htm

The second link provided even showed an interface of Fluent which appeared to be an old version. Since I wanted to see if my results will be influenced on account enabling such an option and since I could not find this option in 2022 R2 version, I posted this question. Could you please provide some more clarification on this? My apologies for any sort of inconvenience. Thank you! 

[Federico Alzamora Previtali]

Hello Pritesh, 

No inconvenience at all! The documents on the link that you shared are from Fluent 12 (2009). I see that from Fluent 18, the option was removed, but the reason is not explicitely documented in any of the release notes.

To add to this, I must say that we typically support the current release, today 23R1, and the two previous releases, today 22R2, 22R1. 

[Pritesh Ramya]

Hello Federico,

Thanks a lot for the clarification.

Given that the model is giving me satisfactory results now, without enabling the Low Re/Damping option and also that it is not available in the current releases anymore, I don't have any further problems. Thanks a lot for your apt response.