Sir, after completion of just 2D nozzle alone, I am again trying to solve this problem with domain as flow visualization is also important.
For 2D nozzle with 1mm unstructured cell sizing I am getting solution which are converging. (Even I did grid convergence test it was working well)
But the moment I add a domain to the nozzle my solution diverges for both type of mesh with and without inflation layers.
After many discussions you told me two important things
1) Check the variation of cells (And I have checked the area ratio its average value is close to 1 and max value is 48 due to inflation layers)
2) Use Adaptation (And according to me there is no point in using this if the solution doesn't stabilize first )
I have uploaded the steps as video in YouTube. And also you can see the mesh quality I am obtaining for the grid. (Please see the video, maybe I am doing something wrong in other settings)
These are the results I obtained after 1000 iteration, you can clearly see that the solution is not stabilizing at any point it just blows off that's why adaptation cannot be applied.
Even for unstructured mesh (both unstructured quad cells and unstructured triangular cells I have tried) the solution is not stabilizing, I don't know for nozzle alone it is working fine but as soon as I add domain to it for flow visualization solution blows off.