4 core & 8 core: same 64bit XP, Xeon, x5570, 2.93GHZ

leeruoyun · August 12, 2009, 15:09

for same *.def file, run both on 4 core & 8 core workstation (other config are same: 64bit XP, Xeon, x5570, 2.93GHZ)

see cpu info here: http://picasaweb.google.com/leeruoyu...56084054998514

4 core is converged within 300 iterations, while 8 core not converged within 300

why ? CPU bothers ?

thanks for advice !

version: CFX12 64 bit

ghorrocks · August 12, 2009, 23:06

It is unusual for adding extra processes to affect the convergence of the simulation. What type of simulation is it?

Glenn Horrocks

leeruoyun · August 14, 2009, 02:58

thank you !

it is really strange. any random initilization for CFX ? e.g., how solver to kick off the flow with the prescribed turbulent intensity ? In this case, we would always get different results for different run (i do not believe this as when i run 2 time in the same pc, results are same), puzzled ........ slower or faster we should always get the same thing ah ...

ghorrocks · August 16, 2009, 08:24

Hi,

CFX only uses random numbers (to my knowledge) in modelling lagrangian particles with turbulence and in generating inlet/initial conditions for LES models. I do not know of any other random numbers used in CFX - but I am not a developer so I am only guessing.

You still have not described what you are doing.

Glenn

leeruoyun · August 19, 2009, 00:47

hi i am doing porous media (seepage flow) problem... i will test another case soon (free surface problem) ...

August 12, 2009, 15:09	4 core & 8 core: same 64bit XP, Xeon, x5570, 2.93GHZ	#1
leeruoyun New Member lee ruoyun Join Date: Aug 2009 Posts: 4 Rep Power: 16	for same *.def file, run both on 4 core & 8 core workstation (other config are same: 64bit XP, Xeon, x5570, 2.93GHZ) see cpu info here: http://picasaweb.google.com/leeruoyu...56084054998514 4 core is converged within 300 iterations, while 8 core not converged within 300 why ? CPU bothers ? thanks for advice ! version: CFX12 64 bit

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August 12, 2009, 23:06		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	It is unusual for adding extra processes to affect the convergence of the simulation. What type of simulation is it? Glenn Horrocks

August 14, 2009, 02:58		#3
leeruoyun New Member lee ruoyun Join Date: Aug 2009 Posts: 4 Rep Power: 16	thank you ! it is really strange. any random initilization for CFX ? e.g., how solver to kick off the flow with the prescribed turbulent intensity ? In this case, we would always get different results for different run (i do not believe this as when i run 2 time in the same pc, results are same), puzzled ........ slower or faster we should always get the same thing ah ...

August 16, 2009, 08:24		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Hi, CFX only uses random numbers (to my knowledge) in modelling lagrangian particles with turbulence and in generating inlet/initial conditions for LES models. I do not know of any other random numbers used in CFX - but I am not a developer so I am only guessing. You still have not described what you are doing. Glenn

August 19, 2009, 00:47		#5
leeruoyun New Member lee ruoyun Join Date: Aug 2009 Posts: 4 Rep Power: 16	hi i am doing porous media (seepage flow) problem... i will test another case soon (free surface problem) ...