Adjoint solution diverging with "Frozen viscosity" option as "No"

diwakaranant · October 7, 2013, 15:53

Hi

I was running adjoint simulation for RANS case for Onera M6 wing on hybrid coarse mesh.

The adjoint simulation is converging with "Frozen viscosity" option as "Yes"
but it is diverging when the option is kept as "No".

Can anyone say why is this happening ?

I am attaching the convergence plot and the .cfg file

Thanks
Anant

economon · October 11, 2013, 16:49

Hi Anant,

Setting the frozen viscosity to NO will enable the adjoint turbulence model (S-A) that is implemented in the code. Including the sensitivity of the viscosity by coupling the adjoint turbulence model can often slow convergence (not to mention that the stability requirements will likely be different too). You might try modifying the numerical methods and CFL number in this scenario to see if you can regain convergence.

Hope this helps,
Tom

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October 11, 2013, 16:49		#2
economon Super Moderator Thomas D. Economon Join Date: Jan 2013 Location: Stanford, CA Posts: 271 Rep Power: 14	Hi Anant, Setting the frozen viscosity to NO will enable the adjoint turbulence model (S-A) that is implemented in the code. Including the sensitivity of the viscosity by coupling the adjoint turbulence model can often slow convergence (not to mention that the stability requirements will likely be different too). You might try modifying the numerical methods and CFL number in this scenario to see if you can regain convergence. Hope this helps, Tom