RSM low Re Stress - Omega convergence issues

Jonathan · September 23, 2015, 17:37

Hi all,

i was wondering whether i could get some help / advice on an issue i am having with the Fluent RSM (stress-omega variant) model.

I have a mesh which converges very nicely with Menters SST model, as well as with the default RSM model (linear-pressure strain model), but i am struggling like heck to get the low Re stress-omega variant to play nicely.

What is different between the setups:

I have the flow out of a nozzle guide vane which i calculate using the same model as the one which i am going to use in the downstream row i am looking at, i create profiles for the velocity / turbulence parameters, and then i solve the downstream blade row.

So for the k-wSST model - i solve the upstream flow with the k-wSST model, and use these BC's with the downstream row. Ditto for the RSM linear pressure-strain model and RSM low Re stress-omega models ... only the latter doesnt converge nicely at all?

Anyone got any experience with RSM models which they might want to share?

thanks in advance
Jonathan

PS i am using the low Re corrections and shear flow corrections as well as coupled PBNS solved in the rotating frame ... 2nd order upwind on everything.

PPS 1st order upwind solves very nicely for the problem at hand

Fabio88 · April 20, 2016, 05:33

Hi Jonathan,

I am actually running unsteady simulations on a cylinder with the RSM-stress/omega. I have similar issues about convergence (simulation explode).
The simulation is working with both k-omega SST turb model and standard k-epsilon wall enhanced model.

Do you find any solution about your problem which maybe can also help me to solve mine?

If you need more detail I can provide you.

Fabio

September 23, 2015, 17:37	RSM low Re Stress - Omega convergence issues	#1
Jonathan Senior Member Join Date: Mar 2010 Posts: 174 Rep Power: 17	Hi all, i was wondering whether i could get some help / advice on an issue i am having with the Fluent RSM (stress-omega variant) model. I have a mesh which converges very nicely with Menters SST model, as well as with the default RSM model (linear-pressure strain model), but i am struggling like heck to get the low Re stress-omega variant to play nicely. What is different between the setups: I have the flow out of a nozzle guide vane which i calculate using the same model as the one which i am going to use in the downstream row i am looking at, i create profiles for the velocity / turbulence parameters, and then i solve the downstream blade row. So for the k-wSST model - i solve the upstream flow with the k-wSST model, and use these BC's with the downstream row. Ditto for the RSM linear pressure-strain model and RSM low Re stress-omega models ... only the latter doesnt converge nicely at all? Anyone got any experience with RSM models which they might want to share? thanks in advance Jonathan PS i am using the low Re corrections and shear flow corrections as well as coupled PBNS solved in the rotating frame ... 2nd order upwind on everything. PPS 1st order upwind solves very nicely for the problem at hand

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April 20, 2016, 05:33		#2
Fabio88 Member Fabio Malizia Join Date: May 2010 Location: Leuven (Belgium) Posts: 51 Rep Power: 16	Hi Jonathan, I am actually running unsteady simulations on a cylinder with the RSM-stress/omega. I have similar issues about convergence (simulation explode). The simulation is working with both k-omega SST turb model and standard k-epsilon wall enhanced model. Do you find any solution about your problem which maybe can also help me to solve mine? If you need more detail I can provide you. Fabio