[anon_p]

Hi,

during my simulations I frequently get the error "recovering.... because transport equations did not converge or energy extrapolations" which keeps the time-step limited. I found another thread in this forum about a similar problem and tried to follow the recommended steps but was not able to find a solution. I tried to adjust the relaxation parameters but it didn't work.

My simulation geometry is a nozzle with needle and sac hole and I added an additional volume at the outlet of the nozzle in form of a cylinder in order to avoid influences of a back flow. I am investigating cavitation and use RANS.

Can you give me some advice how to avoid the extrapolation error please?

Thanks

[Pndsc]

Two things from my experience:

1) Check your BC's. I've had this issue when I had an incorrect inlet mass flow file supplying far less mass than the system would draw. Turns out you cant run CFD on a near vacuum. Who knew?

2) Chill out and let Converge vary the time step for you. The algorithm is really good and this is how I run all the time. You can set max CFLs to vary both with respect to simulation time and have different CFLs in different regions. Remember to set a comically low time step size (1e-8 or lower) to allow the algorithm to handle particularly awkward points.

[Yaju]

It is hard to determine what might be causing these errors without looking at the case. In general, these error might reflect in the temperature and velocity fields. So, you can restart your case and set a low twrite_post value in inputs.in, such that a post file is generated on each time-step. Examine these post files to see if you can determine the problematic location.

Additionally, you send your case to support@convergecfd.com for further support.