CFD Course _ ERROR: residual of Mass is Not A Number: the solver has been stopped

Question

Hi, I always get the following Problem while simulating the half body with a CFL-Number of 3...

The simulation Simulation Half_CFL3 has failed: some NaN have been detected during the computation.
ERROR: residual of Mass is Not A Number: the solver has been stopped How can I fix this? Kind regards

Manuel NIB · Accepted Answer

Hi NicoBu, 
 when the output of the flow solver during the iterations beomces NaN (not a number) it means that teh simulation has diverged. This question also came up during the Q&A of class 1, in case you want to check out the answer in the recording. 
 A diverging simulation can have many different reasons, but one is that the CFL number has been set too high for a particular flow application (sometimes the flow is too complex to converge with CFL=3 and we need to apply a lower CFL number). As this class is also about numerical stability, I cannot go further into detail. 
 Does that help you? 
 Best regards Manuel

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CFD Course _ ERROR: residual of Mass is Not A Number: the solver has been stopped

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