Cuda backend error ‘CudaOutOfMemory’ ‘CudaInvaildDevice’

General
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I’m writting this here as it as good a place as any and will hopefully aid people in the future. The NACA deep stall case is somewhat difficult to run for a number of reasons.

  1. In deep stall there are some very large flow features, consequently the span required to not artifical enforce periodicity is very large. For example, for a low pressure turbine blade a span 20% of chord is normally considered to be acceptable in many circumstances. However, in the paper cited it seems that somewhere between 2 and 4 times the chord was needed.

  2. The case has quite high memory requirments. As a result of the previous point, this cause is quite large in terms of total number of degrees of freedom. This is also compounded by the case having large seperated dynamics, and so there is a large region behind the suction surface where the mesh resolution is higher than what might normally be seen in a fully attached flow.

  3. The time period of the dynamic is quite low, and so has to be run for a long time in order to generate meaningful time averages. This is a consequence of the shedding that is occuring this means that a significant amount of computational resouces are needed if a full run is to be attempted. As either case needs to be run for a long time or strong scaled out to a large number of partitions.

  4. The mesh is not the best quality. This is not to do a disservice to Jin Seok, making meshes for high order methods is challenging and this is a very challenging case, however the mesh quality could potentially be improved and this is a contributing factor to the difficult startup proceedure.

Opinion part:

All in all this is a very challenging case to run and unless you really want to run this case to explore some aspect of the physics that lack understanding I would recommend other cases. If you just want to run a CFD case, I would recommend the SD7003 case at a shallow angle of attack and a Reynold number O(10^5).

This being said, I know that there are some people/organisations out there that use this case as a proof of scaling and this a good candidate. Although, some of the setup requirments make it less than ideal. A worthy alterantive might be the T106 low pressure turbine. There is lots of data out there on it, it is a very standard LES test case, and is much more straightforward to get working.