Unsteady Residuals
 

Hi all,


I am simulating a simple combustor but have been getting steady-unsteady fluctuations of the residual. I have tried many different options to find the source of the fluctuations but have run out of ideas. Any ideas?

It fluctuated like crazy, then settles down nicely for about 100 iterations, then suddenly fluctuated again for about 100 iterations. This cycle happened repeatedly. (I tried to post the screenshot but the forum didn't allow it).



I'm doing a steady simulation, ~300000 node mesh, stoichiometric CH4-air, methane-air-2step.