Residuals in CFX-Solver

Andy

Hello, I got a general question concering the residuals in the CFX-Solver. I had a calculation that did not converge to RMS-resdiual=1e-4 within a certain flow domain. Then I put my article in an adjusted domain which by accident had double the cross section than actually needed (the aim of my adjustment was to reduce the blockage factor from 20 (way too large, I know) to 3 but in the end I had BF=1.5). Within this domain the calculation met the convergence criteria without a problem.

My question is if the explanation can be found in the definition of the RMS in CFX. If the RMS-calculation includes all cells in the same way then I would reduce the RMS-residual just by adding many 'easy' cells that do not experience the complex flow conditions like around my article. If that is right, I could make almost every calculation to converge just by adding a lot of 'easy' cells that is by enlarging my domain. Is there some limiter to this effect except just using the MAX-residual-target?

Regards Andy