Solver for Low-Re medium Mach flow
 

Hello,

I posted a similar question before, which seems to need better definition:

The internal duct flow (hydr.diamater < 1mm) in consideration is characterised by a high pressure loss per length unit (p_in=3.5bar, p_out=2.3 bar, L=100mm), Mach numbers at 0.1-0.3, still low Reynolds numbers < 10000. The density drops along the length due to pressure drop and is calculated by the ideal gas law. As turbulence Models, Low-Re and v2f will be employed. Since the calculation diverges, very low relaxation factors for p and rho had to be chosen.

Star CD offers several solvers (SILMPLE, PISO, SIMPISO) and differencing schemes (UD, CD, QUICK, ...) The question is: is there a combination of solver/differencing scheme that is especially stable for the problem described?