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aerospaceman May 8, 2012 11:20

Best use of an existing PC
Dear all,

I've inherited a machine that I have to use for CFD (Fluent).

Its a quad-core i7 (not Sandybridge), with 16 GB ram.

Its currently running Windows 7. I was wondering what would be the best way to use this computer.

Is W7 the way to go? All this computer will do is solve solutions and post-process (Paraview).

Will running some other OS be more efficient? My simulations are around 1.5 million cells (wished it could be higher though).

Any help would be great, as I'm not too familiar with different OSs.

Many thanks in advance.

CapSizer May 10, 2012 08:32

Nothing much wrong with that machine, especially if you are going to be doing only 1.5 million cell runs. Provided that your Windows 7 is 64-bit, and your software (what are you using?) will run on it, it is unlikely that you will gain anything significant by messing around with a different O/S. In fact, with 16 GB of RAM, you should be good for at least 10 million cells (depends on the solver, of course) - just need to be a little patient!

aerospaceman May 15, 2012 20:08

Hi CapSizer,

Thanks for your reply!

I'm running Ansys Fluent and maybe openFOAM later on.

I think one of the problems is that I'm running transient simulations, so whilst I could probably run 10 million, it would take weeks to solve. With my 1.1 million mesh, it takes about 1-2s per iteration. But with a small time step (1E.4, say) and the necessity to run for say 60-80s, its a lot of iterations.

Thanks for the information. I'm using the 64bit version of Windows as you recommended.

Any tips on optimising the workload on the cores/threads?

CapSizer May 16, 2012 02:20

Well, if you are planning to run OpenFOAM, you should probably consider a switch to Linux. The OpenFOAM developers seem to favour Ubuntu these days, so if you go with Ubuntu you get a very painless install of OF. Your Fluent documentation will probably tell you that the software is only certified on Red Hat and Suse enterprise editions, but in fact you can make it work on almost any Linux distro, perhaps with a little effort. If there is some reason to go with a Red hat-based Linux such as Centos, Fedora or Scientific Linux, there is a compiled version of OpenFOAM called CentFOAM, which makes your life a bit easier.

In terms of optimising your workload, you just have to do some benchmarking to see where you stand with the hyperthreading. Most of what I've heard suggests that you should leave HT turned off for CFD, but there is no substitute for checking this yourself.

You can try "tuning" your BIOS settings for more performance. I once found quite a useful jump in speed simply by installing the latest BIOS, but that is probably a very rare experience. Depending on your CPU and motherboard, you may be able to get a useful boost in performance with overclocking, especially if you first install a really good CPU cooler. Some of the arcane memory settings may help a bit as well, and if you don't have the fastest memory that you can get for your system, it may well be worth replacing it with the fastest, memory being quite inexpensive now.

mjforsteruk June 8, 2012 16:42

Also try caelinux, predistributed with openfoam and other sci packages (based on ubuntu).

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