[Fth9]

Hello

I want to work on turbulent combustion, large eddy simulation, and spray combustion with Ansys Fluent. What kind of workstation would you recommend for solving a model with around 10 million cells, in terms of processor, RAM, etc.?

[wkernkamp]

Originally Posted by Fth9

Hello

I want to work on turbulent combustion, large eddy simulation, and spray combustion with Ansys Fluent. What kind of workstation would you recommend for solving a model with around 10 million cells, in terms of processor, RAM, etc.?

You should fill out the specially prepared questionair here: General recommendations for CFD hardware [WIP]


With your answers, knowledgeable people will be able to answer/guide you.

[Fth9]

Originally Posted by wkernkamp

You should fill out the specially prepared questionair here: General recommendations for CFD hardware [WIP]


With your answers, knowledgeable people will be able to answer/guide you.

Which software do you intend to use?
Fluent, CFX, OpenFOAM
Workbench Meshing, Fluent Meshing

Are you limited by license constraints? I.e. does your software license only allow you to run on N threads?
No license constraints

What type of simulations do you want to run?
Large eddy simulation, spray combustion, radiation heat transfer

And what's the maximum cell count?
10 million

If there is a budget, how high is it?
5000€

What kind of setting are you in? Hobbyist? Student? Academic research? Engineer?
Academic research and engineer

Where can you source your new computer?
Buying a complete package from a large OEM? Assemble it yourself from parts? Are used parts an option?
This can be any option


Which part of the world are you from? It's cool if you don't want to tell, but since prices and availability vary depending on the region, this can sometimes be relevant. Particularly if it's not North America or Europe.
Europe

Thanks a lot

[wkernkamp]

I am not the expert on what to get in Europe. A member flotus is. In the past a budget like yours allowed a dual epyc system. The memory bandwidth is critical for CFD and a large L3 cache positively influences performance. On processors with eight memory channels, the maximum useful cores is about 32. So you would select two epyc 32 core cpus. Pick the ones with the largest L3 cache. This is important, because the cpus with less L3 memory may have fewer dies. This causes a redcued bandwidth to the IO system. An eight channel epyc needs all eight channels to have at least one dimm. The dimms should be the same to get a balanced configuration. Unbalanced configurations have significantly reduced performance. Newer epyc cpus have 12 channels. They are better, but probably out of range for your budget. I saw a post by someone who chose a single epyc of the latest generation. Seems like a good idea, but did not see a comparison. Lets see what flotus has to say.

[Fth9]

Originally Posted by Fth9

Which software do you intend to use?
Fluent, CFX, OpenFOAM
Workbench Meshing, Fluent Meshing

Are you limited by license constraints? I.e. does your software license only allow you to run on N threads?
No license constraints

What type of simulations do you want to run?
Large eddy simulation, spray combustion, radiation heat transfer

And what's the maximum cell count?
10 million

If there is a budget, how high is it?
5000€

What kind of setting are you in? Hobbyist? Student? Academic research? Engineer?
Academic research and engineer

Where can you source your new computer?
Buying a complete package from a large OEM? Assemble it yourself from parts? Are used parts an option?
This can be any option


Which part of the world are you from? It's cool if you don't want to tell, but since prices and availability vary depending on the region, this can sometimes be relevant. Particularly if it's not North America or Europe.
Europe

Thanks a lot

current issue

[flotus1]

If used parts are an option, and you can assemble it yourself:
2x Epyc 7532. They are relatively cheap, 32 cores each, and fully enabled with 256MB of L3 cache. Pair it with 16x16GB of DDR4-3200 reg ECC memory.

For new CPUs, the AMD Epyc 9454 might be within budget. Prices start around 2600€.
Motherboard: 800€
12x16GB DDR5-4800 reg ECC: 1100€
Not too much left for the other parts, but if you can stretch the budget by a few hundred euros, this is probably the better option.

[Fth9]

Originally Posted by flotus1

If used parts are an option, and you can assemble it yourself:
2x Epyc 7532. They are relatively cheap, 32 cores each, and fully enabled with 256MB of L3 cache. Pair it with 16x16GB of DDR4-3200 reg ECC memory.

For new CPUs, the AMD Epyc 9454 might be within budget. Prices start around 2600€.
Motherboard: 800€
12x16GB DDR5-4800 reg ECC: 1100€
Not too much left for the other parts, but if you can stretch the budget by a few hundred euros, this is probably the better option.

Thanks a lot. What do you think about the AMD EPYC™ 9654?

[Fth9]

Originally Posted by wkernkamp

I am not the expert on what to get in Europe. A member flotus is. In the past a budget like yours allowed a dual epyc system. The memory bandwidth is critical for CFD and a large L3 cache positively influences performance. On processors with eight memory channels, the maximum useful cores is about 32. So you would select two epyc 32 core cpus. Pick the ones with the largest L3 cache. This is important, because the cpus with less L3 memory may have fewer dies. This causes a redcued bandwidth to the IO system. An eight channel epyc needs all eight channels to have at least one dimm. The dimms should be the same to get a balanced configuration. Unbalanced configurations have significantly reduced performance. Newer epyc cpus have 12 channels. They are better, but probably out of range for your budget. I saw a post by someone who chose a single epyc of the latest generation. Seems like a good idea, but did not see a comparison. Lets see what flotus has to say.

Thanks a lot.

[flotus1]

Originally Posted by Fth9

Thanks a lot. What do you think about the AMD EPYC™ 9654?

New retail, that's more than 5000€ for the CPU alone.
The cheap ones you find on ebay are all engineering or qualification samples. With everything that entails. Buy at your own risk

There are also severe diminishing returns with more than 48-64 cores on these CPUs. They have a lot of memory bandwidth, but there are still limits for CFD. If you need the higher core count -and the performance that should come with it- you are better off with two 48-core CPUs.

[Fth9]

Originally Posted by flotus1

New retail, that's more than 5000€ for the CPU alone.
The cheap ones you find on ebay are all engineering or qualification samples. With everything that entails. Buy at your own risk

There are also severe diminishing returns with more than 48-64 cores on these CPUs. They have a lot of memory bandwidth, but there are still limits for CFD. If you need the higher core count -and the performance that should come with it- you are better off with two 48-core CPUs.

Is there a seller you recommend on eBay to buy the parts you mentioned or is there an online retail site you recommend?

[flotus1]

I don't have any specific sellers in mind.
Epyc 7532 sold one ebay at reasonable prices all come from China.

For new parts, I usually start searching here: https://geizhals.eu/?cat=mbsp3&xf=49...DIMM%7E644_SP5

[Fth9]

Originally Posted by flotus1

I don't have any specific sellers in mind.
Epyc 7532 sold one ebay at reasonable prices all come from China.

For new parts, I usually start searching here: https://geizhals.eu/?cat=mbsp3&xf=49...DIMM%7E644_SP5

Hello again, What do you think of these processors?

AMD EPYC™ 9554
Intel® Xeon® Gold 6530
Intel® Xeon® Gold 6554S
Intel® Xeon® Platinum 8558U
Intel® Xeon® Gold 6542Y
Intel® Xeon® Gold 5520+
Intel® Xeon® Gold 6538Y+
Intel® Xeon® Gold 6548Y+
Intel® Xeon® Gold 5512U
Intel® Xeon® Gold 6548N
Intel® Xeon® Gold 6538N