Solution not converging, but oscillating residuals around a constant value
 

Hi Fluent users,

I am a new fluent user and I am analysing an impingement system for a vane internal cooling passage, using a realizable k-eps model.
I started using a incompressible ideal gas, the solution converged without any problems but the calculated density was completely wrong, so I changed the material as an ideal gas. Now my solution doesn't converge anymore: all the residuals oscillate around a constant value, and in particular the continuity residuals oscillate around a value which is far from the convergence criteria one.
I tried to change the under relaxation factors (it dumps the oscillatins but it doesn't improve the convergence), to use a finer mesh and to use the fluent mesh adaptation tool but without any results.

Can anbody help me?

Cheers

Irene

It is difficult to judge from the few information you gave
What is the pressure and velocity value at the injection system (or maximum pressure in the system) ? Do you have good values of y+ ? Did you check the quality of your mesh ?

Below are a few things you could try :
- Using the density based solver
- start with a lower mass flow (or velocity or pressure) inlet and increase it gradually
- Start by an inviscid flow then add turbulence

GG

I think your case is transient! not steady-state.