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Old   September 26, 2012, 15:14
Default 64 bit CPU
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Hi Foamers,

i have 64 bit CPU, but unfortunately i have 32 bit UBUNTU. could this affect running of openFOAM, or shall i replace mu UBUNTU with 64 bit version.

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Old   September 27, 2012, 07:56
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wyldckat is just really nicewyldckat is just really nicewyldckat is just really nicewyldckat is just really nicewyldckat is just really nice
Greetings Ahmed,

Well... it all depends on several details:
  1. Depends on how much RAM your machine has. If you have more than 2-3GB of RAM, then I think you should take advantage of using the 64bit processor.
  2. If you have lesser than 2-3GB of RAM, it's a matter of how much performance do you really need?
    For example, from this page - you'll find these two times:
    • OpenFOAM 2.1.x 32bit: simpleFoam took 896s to run.
    • OpenFOAM 2.1.x 64bit: simpleFoam took 685s to run.
    As you can see, in this case it was about 30% faster to use 64bits.
  3. Do you have Ubuntu installed in a virtual machine? If so, things get a lot more complex, because it depends on the virtualization capabilities of the CPU, real Operating System and the virtualization software you're using.
So basically, if you do want to take advantage of your 64bit CPU, the best would be to install a 64bit Ubuntu, as you asked.

Best regards,
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