[RemyCavecchia]

Hi everybody,

I'm coming to you cause I'm stuck with kOmegaSSTLM transition model, I'm trying to validate it in different conditions for a research study on laminar/turbulent transition.

I've tried to use this model on the T3A tutorial which works quite well, I 've compared the results to the original paper of Langtry and Menter and plotted Cf/Re for the experimental data, the kOmegaSST and the kOmegaSSTLM.
The results seem quite good:



As we can see the kOmegaSST version is acting fully turbulent and the kOmegaSSTLM seems to find the good transition position for a turbulent viscosity ratio of 12 as described in the 2009 paper.

But when I change the BCs to simulate the T3B or T3A- conditions things are going bad. I've done the BCs calculation like a hundred times to be sure and doesn't seem to make any mistake.



Here the kOmegaSST is acting fully turbulent as expected but the kOmegaSSTLM seems to behave fully laminar like no transition occurs.
I've done a small correction in the case cause I found out, in the experiment details, that the flat plat as an angle of attack of 0.5degrees to avoid the detached flow at the leading edge which was not the case in the tutorial.
Thought it would solve the problem but even if the kOmegaSST behavior seems better there is nearly no change to the kOmegaSSTLM.


I give you below the details of my inlet BCs just to let you know. I didn't change any of the wall BCs from the tutorial.



I have checked all the source code of the model and didn't see any difference with the original one proposed by Langtry and Menter.


If someone as any idea this would help me!!


Thanks.

[syavash]

Originally Posted by RemyCavecchia

Hi everybody,

I'm coming to you cause I'm stuck with kOmegaSSTLM transition model, I'm trying to validate it in different conditions for a research study on laminar/turbulent transition.

I've tried to use this model on the T3A tutorial which works quite well, I 've compared the results to the original paper of Langtry and Menter and plotted Cf/Re for the experimental data, the kOmegaSST and the kOmegaSSTLM.
The results seem quite good:



As we can see the kOmegaSST version is acting fully turbulent and the kOmegaSSTLM seems to find the good transition position for a turbulent viscosity ratio of 12 as described in the 2009 paper.

But when I change the BCs to simulate the T3B or T3A- conditions things are going bad. I've done the BCs calculation like a hundred times to be sure and doesn't seem to make any mistake.



Here the kOmegaSST is acting fully turbulent as expected but the kOmegaSSTLM seems to behave fully laminar like no transition occurs.
I've done a small correction in the case cause I found out, in the experiment details, that the flat plat as an angle of attack of 0.5degrees to avoid the detached flow at the leading edge which was not the case in the tutorial.
Thought it would solve the problem but even if the kOmegaSST behavior seems better there is nearly no change to the kOmegaSSTLM.


I give you below the details of my inlet BCs just to let you know. I didn't change any of the wall BCs from the tutorial.



I have checked all the source code of the model and didn't see any difference with the original one proposed by Langtry and Menter.


If someone as any idea this would help me!!


Thanks.

Hi Remy,

This thread looks interesting. How did you take the turbulent intensity into account?
What about the mesh resolution? Did you examine the sensitivity of the results to streamwise and wall-normal mesh resolution??

Syavash

Edit: I see in the table you provided that exact values of omega and k are calculated!

[RemyCavecchia]

Originally Posted by syavash

Hi Remy,

This thread looks interesting. How did you take the turbulent intensity into account?
What about the mesh resolution? Did you examine the sensitivity of the results to streamwise and wall-normal mesh resolution??

Syavash

Edit: I see in the table you provided that exact values of omega and k are calculated!

Hi Syavash,

Thanks for your interest.
About the turbulence, as you noticed after, I took it into account calculating k, omega and Retheta.
About the mesh I allready tried finer meshes in both direction without any change, but it seems that I can find something close to a transition (but not at the good location) with a coarser mesh, i'm gooding deeper in this way and I'll let you know.

[syavash]

Originally Posted by RemyCavecchia

Hi Syavash,

Thanks for your interest.
About the turbulence, as you noticed after, I took it into account calculating k, omega and Retheta.
About the mesh I allready tried finer meshes in both direction without any change, but it seems that I can find something close to a transition (but not at the good location) with a coarser mesh, i'm gooding deeper in this way and I'll let you know.

Remy,

Thanks for sharing your findings. I will look forward to hearing more on this interesting subject.

Regards,
Syavash

[purnp2]

Hello, Remy,
Can you share case files of all the three flat-plates? Did you create these cases by yourself?
I am working on a similar topic where I'll be using an EARSM model (with laminar-turbulent transition equations) for simulation.
Thanks.