Workstation specs for unsteady aerodynamics

Mahd · September 8, 2022, 03:28

What would be an appropriate workstation to simulate 3D unsteady dynamic mesh computational aerodynamics (compressible/incompressible)
problems with about 80 million cell domain using Ansys Fluent? Also it would be better if the same workstation has capabilities to simulate fluid structure interactions.

Actually I need to submit some proposals (budget vs solving time). Hence, the budget has not been determined yet, but the simulation has to be done in an acceptable time (within few days to a week maximum).

If anyone has an idea about the core*hours (@3GHz) for such simulations that will be so helpful.

Any help will be appreciated

flotus1 · September 8, 2022, 17:07

It will be nearly impossible to estimate how long your simulations will take on any given hardware. There are just too many variables involved.

From your requirements thouch I would say you should be shopping in the 20k-25k€ price range. Transient, dynamic mesh and 80 million cells are fairly challenging. I would not go below two Milan-X CPUs and probably even 512GB of RAM. 256GB might be enough, but it could be pretty close. I'd rather be conservative here, doubling memory won't add too much to the total cost.
And please check how many threads your Fluent licenses are good for.

The other option is always going to a cluster. You can get even faster solver times than on a single workstation, and your upfront costs are much lower. Again, licensing is a factor here. There is no use for thousands of cores if your licenses only allow e.g. 128 threads.

wkernkamp · September 9, 2022, 01:17

Mahd,

Perhaps your engineers have a sample problem that they could run on an AWS server. That should give some insight into convergence and run time.

The run time can be adjusted for a difference in processors, cores, cache, and memory for your system configuration.

Mahd · September 9, 2022, 01:56

@Alex
Thank you for your reply, that was helpful.
The number of threads for the Fluent licenses will be studied based on our needs.
So do you have suggestions for the cluster specs?

@wkernkamp
Thanks. The current resources are quite poor, extrapolating from small domain to a large one might work for determining some of the configurations like RAM, but for the solving time, I think it's difficult to be estimated by linear extrapolations.

September 8, 2022, 03:28	Workstation specs for unsteady aerodynamics	#1
Mahd New Member Daniel Join Date: Jun 2020 Posts: 3 Rep Power: 5	What would be an appropriate workstation to simulate 3D unsteady dynamic mesh computational aerodynamics (compressible/incompressible) problems with about 80 million cell domain using Ansys Fluent? Also it would be better if the same workstation has capabilities to simulate fluid structure interactions. Actually I need to submit some proposals (budget vs solving time). Hence, the budget has not been determined yet, but the simulation has to be done in an acceptable time (within few days to a week maximum). If anyone has an idea about the core*hours (@3GHz) for such simulations that will be so helpful. Any help will be appreciated

September 8, 2022, 17:07		#2
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	It will be nearly impossible to estimate how long your simulations will take on any given hardware. There are just too many variables involved. From your requirements thouch I would say you should be shopping in the 20k-25k€ price range. Transient, dynamic mesh and 80 million cells are fairly challenging. I would not go below two Milan-X CPUs and probably even 512GB of RAM. 256GB might be enough, but it could be pretty close. I'd rather be conservative here, doubling memory won't add too much to the total cost. And please check how many threads your Fluent licenses are good for. The other option is always going to a cluster. You can get even faster solver times than on a single workstation, and your upfront costs are much lower. Again, licensing is a factor here. There is no use for thousands of cores if your licenses only allow e.g. 128 threads. Mahd likes this.

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September 9, 2022, 01:17		#3
wkernkamp Senior Member Will Kernkamp Join Date: Jun 2014 Posts: 308 Rep Power: 12	Mahd, Perhaps your engineers have a sample problem that they could run on an AWS server. That should give some insight into convergence and run time. The run time can be adjusted for a difference in processors, cores, cache, and memory for your system configuration.

September 9, 2022, 01:56		#4
Mahd New Member Daniel Join Date: Jun 2020 Posts: 3 Rep Power: 5	@Alex Thank you for your reply, that was helpful. The number of threads for the Fluent licenses will be studied based on our needs. So do you have suggestions for the cluster specs? @wkernkamp Thanks. The current resources are quite poor, extrapolating from small domain to a large one might work for determining some of the configurations like RAM, but for the solving time, I think it's difficult to be estimated by linear extrapolations.