Are Ryzen processors good for CFD simulations

Hardware configuration for FEM simulations

Optimal PC for FE calculations

The range of FE calculations is large: from a simple framework model with a few hundred nodes to extremely complex calculations with several million degrees of freedom. We do not want to cover this range and concentrate on "usual calculations", as they are typically carried out in the design process for strength assessment. Typical models of this category can be found on our FEM calculation page.

These models usually look like this:

  • A maximum of 600,000 nodes for non-linear calculations (e.g. screw calculations)
  • Maximum of 2 million nodes for linear calculations
  • Static analyzes as well as modal analyzes

 

processor

With most FEM software packages, the number of cores that can be used for calculations is limited depending on the license. For example, Ansys can count on 4 cores for a medium five-digit amount. It does not make sense to increase the number of cores in the processor beyond this. The additional cores are not used for the calculation. This problem can be circumvented by purchasing licenses for additional cores, which is, however, very costly and is only worthwhile for calculating very complex problems.

When choosing the processor, the clock frequency of the cores and the operations per clock are essential. The operations per cycle (which were the main reason for the speed difference in the example above) are largely determined by the AVX extensions. Our recommendation today (2019) is to use a processor with AVX512. The manufacturer AMD does not currently have a processor with AVX512, so that only Intel remains in the selection. A suitable processor would be the Xeon W-2125, for example.

It should be noted that the cheaper processors sometimes only have one AVX pipeline per core. This should be avoided.

Every now and then you hear the opinion that you should have more cores than are used for the simulation. In our computers, the number of processors cores corresponds to the maximum usable cores (depending on license). Nevertheless, further work (e.g. writing a calculation report, Excel tables, ...) while the FE calculation is running is no problem.