topic Re: Converging-Diverging Nozzle Divergence When Solving in CFD Forum

Converging-Diverging Nozzle Divergence When Solving

Anonymous — Mon, 07 Jan 2019 19:14:30 GMT

I am trying to test a converging-diverging rocket nozzle by following the tutorial here. I followed that tutorial exactly, using the dimensions of their nozzle, and it came out almost perfect. That could be how I designed the nozzle compared to theirs. I am attempting the same procedure with my nozzle, but with no luck. I have tried refining the nozzle mesh several times using the size adjustment and surface refinement, but I only ever get to iteration 5, where it gives me the error message that the analysis was stopped due to divergence, and Autodesk 360 stops working, but that is another problem. I have attached my nozzle file, created in Inventor, as I needed an equation curve for the bell. I welcome any and all suggestions to be able to get this working.

Re: Converging-Diverging Nozzle Divergence When Solving

marwan_azzam — Mon, 07 Jan 2019 22:10:29 GMT

Hello there,

Thank you for reaching out to the community.

You mention Autodesk 360. Are you using Autodesk CFD? If so, which version?

Also, if you are using Autodesk CFD, please send us the support share file (*.cfz) of your model so we can work with it here.

The ipt file is just the geometry and without the setup we cannot duplicate the analysis you have.

Cheers,

Marwan

Re: Converging-Diverging Nozzle Divergence When Solving

marwan_azzam — Tue, 08 Jan 2019 14:38:47 GMT

Hello Luke,

I see that you did not post the cfz file. That is OK.

I opened the ipt file you posted and the geometry stood out as a possible cause for your convergence issue.

The problem is with the circled end in the image below:

You do not leave any room for flow to develop.

Extend that end to something like this and try again.

I'm also attaching a new ipt file with the modified geometry.

Please let us know if that solves the problem.

Regards,

Marwan

Re: Converging-Diverging Nozzle Divergence When Solving

Anonymous — Tue, 08 Jan 2019 20:04:11 GMT

Thank you, next time I will try and attach the actual file used with CFD, and specify my version of Inventor and CFD.