[siw]

Hi,

I'm running a transient external aero simulation around some bluff bodies (ICEM hybrid mesh ~20 million elements - on my 8 core PC takes ages to run). Re = 6 million.

I did the usuall steady state simulations (SST k-omega) to determine mesh and physcial time scale sensitivity in order to get a flowfield to initialise the transient run.

I expect a turbulent flowfield behind the bluff bodies with a range of scales - not a periodic shedding of vortices. So I don't know what transient time set-up to use. Therefore, following Glenn's reply (http://www.cfd-online.com/Forums/cfx...e-problem.html) I'm using the adaptive timestepping to CFX can work it out it self.

But I've found the RMS residuals have increased greatly (see image of the run in progress). In using the SAS-SST with Bounded CD advection scheme following the ANSYS SRS Best Practice document. I could not get the residuals any lower in the steady state run as the mesh size was getting far too large (however, the steady state monitor points became constant and the imbalances were all 0%).

Should I let this simulation to continue (it'll take ages) or does anyone known how to improve things. I'm also watching the monitor points which are starting to oscillate (which I expect was they are points in the turbulent wake).

Thanks