||March 14, 2011 15:59
I am running an alpha sweep on a serrated leading edge wing (top view attached entitled "Wing"). Basically setting the wing at varying angles of attack with respect to the free stream in order to obtain lift and drag coefficients. However the simulation was having trouble converging at a low value and i'm wondering if anybody can comment on why this is and/or how to ensure it converges lower.
The simulation is run at a Reynold's Number of 3 million and the number of cells are listed on each picture with the Spalart-Allmaras as my turbulence model. You can see that as cell density increases, some of the residuals smooth out but they don't drop more than three orders of magnitude. The flow domain, as shown in "Slide1" is divided into a higher density region (Body#1) surrounding the Wing and a lower density region (Body#2) in the outer region.
This simulation is in Star-CCM+ but i'm hoping this question about residuals and convergence is generic enough to apply to CFD as a whole. I would also like to avoid playing with under-relaxation values in order to ensure accuracy.