Oscillating Residuals
Hi all
I'm calculating a flow arround a Turbofans nacelle with mixing of core and bypass massflow using a 6 million nodes large grid. I have a converged solution for a freestream velocity of 50m/s and I now want to simulate the flow at different freestream velocities. Unfortunately the residuals for the velocities, energie and continuity are beginning to oscillate after 100 Iterations in between 1e1 and 2e1 with an amplitude of around 1e1 and no convergence is reached. My Simulation parameters are: Solver: Coupled explicit parallel on 8 cpus Gas: Ideal Gas Law for Compressible Flows Turbulence: Realizable keps CFL: 0.2 Maybe a multigrid can solve the problem??? Thanks for any suggestions. Cairol 
Re: Oscillating Residuals
ups ...

Re: Oscillating Residuals
What about changing the underelaxation parametres for velocity , If I were you I would decrease underrelax parametre 0.1 point and then see what happens

Re: Oscillating Residuals
Thanks for your Answers
I changed the underrelaxation parameter as well as the CFLNumber to 0.1 and used the coupled implicit solver instead of the explicit like Razvan suggested. Unfortunately, the same oscillation appears after a 100 iterations. Again, my simulation parameters are: Solver: Coupled implicit parallel on 8 cpus Gas: Ideal Gas Law for Compressible Flows Turbulence: Realizable keps  first order upwind CFL: 0.1 Massflows on inlets and outlets are more or less steady during the run, that is no oscillation appears in Massflow! Cheers Cairol 
Re: Oscillating Residuals
I took the segregated solver and .................................................. .................................................. ............... it is going to converge
Cheers Cairol 
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