Simulation diverges at different flow velocity

I’m doing a simple aerodynamic analysis of a wing, at different flow velocities. In ‘Run 1’, the velocity is set at around 115 m/s and everything works great, with results that converge nicely. However, upon increasing the flow velocity to 150m/s, results did not stabilise. This can be seen in the run called “150 m/s divergent :(” and all the runs after that, especially the last one called “150 again longer”.

I tried refining the mesh but the problem persists. I subsequently realised that since i made the run time much shorter than than that of Run 1, it could be that it simply wasn’t running for long enought to converge, so I increased it in the runs called “150 longer”, but it didn’t help. Other than run time and flow velocity in boundary conditions, no settings or parameters were changed at all, so I don’t understand why the first run worked and the others don’t.

Link:

Hey @SultanaShah ,

All runs are successful from what I see and that is because they ran without excessive divergence trend until the number of iterations set by you. May I ask why you are checking the results of the first (converged with 3000 iterations) run with a run with only 200 iterations?

I suggest you run the simulations with default settings of at least 3000 iterations and wait for convergence or explicit divergence information. And then improve mesh quality if you do get a diverged residual plot.

Best,
Satvik

Hi , thank you for replying

I have already ran the simulation for 3000 iterations, it’s the last run called “150 again longer”. While the run was succesful, the force coefficients and residulas graphs have very diverging results, unline the first run called Run 1