SimScale CAE Forum

Results not converging properly

Hi I made these models in fusion 360 and was running them for CAD analysis. In most of the simulations, the x directional velocity has converged while the other two have not. I am calculating the drag in the x direction so should I be worried about this, if yes then how can I improve convergence. As well as that in Residual readings the “omega” reading is fluctuating a lot. So should I be worried about that and if yes how can I improve its convergence.

Link for the simulation:
https://www.simscale.com/workbench/?pid=3459659064222237020&rru=d20fc1c6-e637-4583-b0ce-39f6734733d8&ci=fdd0f042-42c6-42a3-bc3d-4967e3e1df08&ct=CONVERGENCE_PLOT&mt=SIMULATION_RESULT

Best Regards
Ishaan Agarwal

Hi Ishaan,

Welcome to the forum!

To improve convergence, I think you have to refine the mesh. Specially, adding a region refinement around the body is very useful. Also, the local mesh size in the body can be decreased multiple times to perform a mesh independence analysis.

Hi @ggiraldof thanks for the response. I tried making the mesh finer for the simulation setup called “Sidepod 2” which I ran as “Run 3”. However, the results seemed to be more converged in “Run 2” where the mesh was coarser. So I am not sure why this is happening. So if possible could you check the runs and tell me how can I ensure convergence.

Link for the simulation:
https://www.simscale.com/workbench/?pid=3459659064222237020&mi=spec%3A42ca2cee-1eb3-49e9-8ddf-f2df526263a5%2Cservice%3ASIMULATION%2Cstrategy%3A41

Best Regards
Ishaan Agarwal

I’m sorry I missed this the first time, but your enclosure is too small, compared with the size of the body. The flow needs proper space between the body and the boundaries to properly develop.

I would recommend you to use the proportions outlined in these tutorials:

Also, as you would be into it, I suggest you to leverage symmetry to save on computation time.

Hi @ggiraldof thanks for the reply. So I followed the article and setup my simulation and ran the simulation “Run 2” under “Copy of Sidepod 2”. However upon checking convergence I realized that Uz and Uy were not converging in the Domain and Walls plot and had random spikes in the Inlet plot. The same can be said for the P in the outlet plot. Therefore I made the mesh finer and ran “Run 4”. Despite the mesh being finer the results were less converged. Could you please tell me why I am getting these spikes and why upon making my mesh finer the results are less converged. Hence what do I need to do to achieve proper convergence.

Photo of “Run 2” Inlet plot:

Photo of “Run 4” inlet plot

Best Regards
Ishaan Agarwal