Unusual Jump in Scaled Residual
 

Hi,
I am currently doing a 3D simulation for an aircraft.
model- k-w sst
steady-state pressure based solution
Mesh Quality:

Minimum Orthogonal Quality = 1.17479e-04 cell 796080 on zone 2 (ID: 1405101 on partition: 1) at location (-1.39139e+01 2.22699e+00 8.14461e+01)

Boundary conditions
velocity inlet
pressure outlet

Solution method
Coupled and second order for the rest.

During the solution phase, I get huge spikes in the calculation for both lift and drag force.
also, a message is posted " Stabilizing pressure coupled to enhance linear solver robustness." - don't know what it means.

I have attached images.
Any help would be appreciated.

Yeah that's what happens when you have a bad mesh. Your minimum orthogonal quality is pretty bad. You might want to start there.


Also you can make a plot of pressure or velocity at a bunch of places and see if you can find where the problem is. It should be quite apparent.

I tried improving the mesh quality. but it always gives the orthogonal quality as that. could you please suggest any way of improving the mesh quality?

Bad meshes are often times a result of people being too smart for their own good.

You keep getting bad mesh because you are repeating the same bad habits when you create the mesh. Figure out what this bad habit is and stop it. Unfortunately it's hard to figure out from just a report what this bad habit is. Especially when I have no clue where the bad cells are.

Could you please do what I already said and find the bad cells first? Try to change those.

Another suggestion that might take longer, mesh a very simple configuration like a box or a pipe so you can learn what are the key steps of meshing.