Influence of number of cores and processor speed (GHz) in thermal simulations on ANSYS APDL
I am facing a problem whose theme I do not see clearly in the Ansys documentation, so I hope that someone here on the forum can give me some information.
I currently work with 2 computers with the following configurations:
RYZEN 2700 with 8 cores at 3.2GHz with 16 GB of RAM
XEON GOLD 5120 with 28 cores at 2.2GHz with 64 GB of RAM
Both with hypertreading disabled, and the simulations are running INCORE. Licenses are set up correctly.
My simulation consists in transient non-linear thermal simulation, using SOLID70 and SURF152 elements. ~210.000 nodes and ~270.000 elements. Conductivity and enthalpy as function of temperature. I also use element birth and death. I use JCG solver with default configurations (I already tested sparse solver and its slower).
The point is that, with 8 cores (SMP) on both pcs, the Ryzen one is approximately 30% faster ("Elapsed time spent computing solution(s)" in output file).
If I increase the number of cores in Xeon to 16, the difference remains the same, or even gets a little worse.
I know that after a certain point, increasing the number of cores does not decrease computational time.
So, my doubts:
1- Is there a way to predict the optimal number of cores to be used in a simulation, without having to do manual tests? (Like run with 4, 8, 16 cores, note the times and make a curve.)
2- Does the processor clock (GHz) have so much influence on the solution? Since when I use 8 cores on both PCs, Ryzen resolves much faster.
3- The main reason for my doubts is that a Ryzen desktop is currently being faster than an expensive Xeon workstation. Are we wasting money here?