topic Re: Different results with same cfz files(same settings) in CFD Forum

Different results with same cfz files(same settings)

joy.hong — Wed, 20 Apr 2022 06:19:42 GMT

Hi guys,

I'm new to CFD. My colleague sent me a cfz file with his settings, material, boundary conditions, meshing(automatic meshing), then I run the solve without any modification, but my results is significantly different from his, iteration times are different, can somebody tell me the reason? Do I miss some settings? I don't know which one is correct now, it will impact on our design a lot.

Thanks in advance, and I also attach the zip file

Joy

Re: Different results with same cfz files(same settings)

karol.suchon — Wed, 20 Apr 2022 11:56:52 GMT

Hello Joy,

Probably the results are the same, but the software just stopped the calculation too early( you could ask your teammate to create the convergence plot from 1 to 158 iterations, you could type the value on the bottom).

If we have everything on the auto it could happen that convergence is too coarse and it ends the calculation too soon, to change that go to solve->solution control->advanced and move the slider into the tight region, just not too much.

That allows to tighten the criteria and in most cases allows to reduce the numerical error of the calculation. In the simulation with everything on the auto settings the temperature like to be a little too high, especially in natural convection analysis.

Best regards,

Karol

Re: Different results with same cfz files(same settings)

joy.hong — Wed, 20 Apr 2022 13:24:43 GMT

Thank you Karol

Can I set a specific value of iterations before start to solve, I want to check if I have the same result when I have 188 iterations, same as my teammate, to make sure nothing else is missed

Joy

Re: Different results with same cfz files(same settings)

karol.suchon — Wed, 20 Apr 2022 13:32:54 GMT

Convergence criteria will have an impact on the results, if we tighten the criteria, the change of the value between the iterations will be smaller, so you cannot compare the results like that.

But I think that you could just continue the calculation without any changes, there is a chance that the software will continue the calculation and stop at exactly the same point as your teammates.

Best regards,

Karol

Re: Different results with same cfz files(same settings)

joy.hong — Wed, 20 Apr 2022 13:39:04 GMT

Understood, thank you