[karananand]

I have a model where the turbine blades are cooled internally. The discretization to NS equation was first performed with 1st order upwind for momentum, energy and viscous model chosen and standard for pressure. The gradient was calculated with Least squares Cell based. the solution converged with residual set to 1e-4 for all except 1e-6 for energy.

After the solution converged, to get more accurate results, I switched to Second order upwind for all except pressure which was left as standard with gradient calculated with Least squares Cell based. This time however the solution seems stagnant with continuity at 1e-2, turbulence at around 5e-4 and momentum around 2e-4 energy is at 1e-5. I started with the converged solution to begin with.

Why is it that the solution is not getting converged for second order upwind? Is there a way I can force the solution to converge for this discretization method?