[boddyouareboy]

hello Everyone,
I am a new guy of OpenFoam, nowadays I come to a problem that I can not solve. So I came here for help.

It is about the convergence rate of simpleFoam (details of schemes, plots can be found in the attached file) The tol is 1e-9, but it seems to be heavy oscillation when residual is low than 1e-7, and it takes such a huge number of iterations to further decrease the residual. I tried to change the discretizing scheme of divergence, (change upwind to SFCD) but there always be FOAM error : "attempt to reach EOF", I have no idea but change the last item "div((nuEff*dev(grad(U).T())))" back to "Gauss linear", and the results seems to be not correct.

So my question is that "Is there something I can do to improve the convergence rate?" BTW, the Tol should not be changed, because I need this kind of precision. And I also hope that some one can explain why to do this, I'd really appreciate it!

BR!