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EARSM Turbulence model

sima101f

HI.

I am trying to run a simualtion for axial compressor. I have previously done simualtion for same mesh with S-A, Kw-SST and EARSM(baseline). I was interested in running with EARSM by hellsten, so I changed the expert parameter IEASRM=1(suggested by manual) but my simulation diverges as soon as simulation shifts to finer mesh. I tried to run simulation at coarse mesh(1 1 1) which works veryy well and then use this as intial solution to run at fine mesh (0 0 0) but simualtions diverged. I tried using intial solution  of EARSM base model but that also didnot work. 

Could you please suggest here something ?

Thank you very much

Sid

  • Gaurav
    0

    Hi,

    If you are using fine mesh (0 0 0), in that case, change your CFL number to 1 or check with a value less than 1.0.

    Have you checked the IEASRM turbulence model without using the simulation data of the coarse grid (1 1 1), as the initial solution?

    Activate your coarse grid initialization and keep the number of grid levels at 3.

    You can also try other combinations, such as 2 3 1 or 0 3 2; verify that the same convergence problem exists or not.

    Suppose you are using the CPU booster, and if you notice the oscillating type solution, then you can change your multigrid sweep direction from increasing on a higher level to linear progression. (Try without a CPU booster.)

    GS

  • Colinda
    +1

    Hi,

    Could you get the simulation converged?

    If not, I would have a few questions:

    • Which version of Fine Turbo are you using?
    • At which conditions are you running, operating conditions or e.g. close to stall?
    • Can you please show a convergence plot for the simulation with baseline EARSM, both for the density residuals and the turbulence quantities? What did you use as initial solution for this simulation?
    • What is the motivation to run the model by Hellsten? Is it because the result with the baseline model does not meet your expectations? If so, why?
    • Have a look at the results of the coarse mesh simulation in CFView, inspect it very carefully: the velocity field, pressure and temperature in the whole domain, as well as the turbulence quantities: are they as expected? 
    • Is the divergence immediately in the first iteration on the finest grid level or after a few iterations. In the latter case save the solution just before the divergence and carefully inspect it to see where possible unphysical results are located in the domain.
    • How did you define the inlet boundary conditions, including those for turbulence? 

    Best regards,
    Colinda

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