[kaeran]

Hello everyone,

I got a big problem in convergence while simulating in Fluent.
I have almost tried all steps that has been suggested in a thread about convergence by CENTURION 2011(http://www.cfd-online.com/Forums/flu...nvergence.html). But I couldn't solve my problem. Let me explain it first.

Inorder to run a transient simulation, initial converged inputs are essential. So, I ran a steady state pressure based simulation.
Convection and conduction processes takes place in quenching. So,obviously energy and turbulent model (k-w) were switched on.
I used pressure based coupled solver with pseudo transient method to speed up the convergence.
The discretization schemes were (default),
Pressure- Standard
Momentum- second order upwind
Energy- second order upwind

I have tried Higher order term relaxation with default (0.75) relaxation factor and also 0.25 (in another simulation). The simulation ran for 5000 iterations with pseudo time step of 1e-05.

The result was not so convincing i.e., the solution was not converged.
At the end of the simulation, my conservative terms (residuals)were of the order
continuity e-03
momentum e-05 in x direction
e-04 in y direction
e-05 in z-direction respectively
energy e-17
mass imbalance e+02

These residuals keeps on oscillating and I couldn't standardise the solution.I have also cross-checked the mesh. It has decent orthogonal quality and skewness (non-conformal mesh).

Minimum orthogonal quality is 0.20
Max. Skewness is 0.85
Max aspect ratio is 45

but, these values are accepted as the geometry of the CAD model is relatively complex.

And my question here is , should I try for more iterations or should I further reduce relaxation terms?

If there are any other suggestions, it is always welcome.
And please correct me, if the steps that I mentioned here are inappropriate.

I have been struggling with this problem for more than 2-weeks. I really need some help