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-   -   "Memory too low" problem with Fluent HELP NEEDED (http://www.cfd-online.com/Forums/fluent/40851-memory-too-low-problem-fluent-help-needed.html)

Amr May 6, 2006 08:10

"Memory too low" problem with Fluent HELP NEEDED
 
All,

I am simulating a 3-D hall with half-million cells. I am solving terbulence, energy, flow and three species. When I meshed the geometry in Gambit, every thing was okay. Then, after I exported the mesh into Fluent (version 6.0) and when I came to initialize the solution, it took a lot of time and poped up a message "Vertual memory too low".

I am using Win XP with 256 MB RAM, Intel 1.8 GHz processor. I figured out from my search on this forum that my hardware could work well. Now, is there a problem with the gambit set up?. Any ideas how to solve this problem?.

P.S: I tried to increase my paging file (vetual memory) up to 1 GB with no good.

Cheers,


Adriano May 6, 2006 08:46

Re: "Memory too low" problem with Fluent HELP NEED
 
Hi Amr, half-milion cells mean 1mln of nodes... too much for your RAM+paging. Anyway it's hopefull do not use virtual memory cos pc goes very slow!!!Let's try to mesh your model with less cells.

Adriano

Amr May 6, 2006 09:11

Re: "Memory too low" problem with Fluent HELP NEED
 
Hi Adriano,

I need to double echeck my count of cells with you. When I checked the overall volume mesh in Gambit, it says 490678 elements (I guess this means 3D cells right?). And below is the summary script when Fluent first reads the mesh file. Does this script below show that I had a problem in Gambit zone boundary set up?. Note that a used clever volume decomposition in order to use all Hex cells. I hope that this decomposition doesn't make any problems anyways. I checked the grid with Fluent and Ganbit and it gave me no errors.

32 hexahedral cells, zone 2, binary. 490844 hexahedral cells, zone 3, binary. 1432063 quadrilateral interior faces, zone 15, binary.

32 quadrilateral wall faces, zone 1, binary.

44206 quadrilateral wall faces, zone 4, binary.

16 quadrilateral interior faces, zone 5, binary.

18284 quadrilateral interior faces, zone 6, binary.

16 quadrilateral velocity-inlet faces, zone 7, binary.

16 quadrilateral wall faces, zone 8, binary.

48 quadrilateral wall faces, zone 9, binary.

9 quadrilateral pressure-outlet faces, zone 10, binary.

9 quadrilateral pressure-outlet faces, zone 11, binary.

48 quadrilateral wall faces, zone 12, binary.

9 quadrilateral pressure-outlet faces, zone 13, binary.

9 quadrilateral pressure-outlet faces, zone 14, binary.

64 quadrilateral interior faces, zone 16, binary. 513175 nodes, binary. 513175 node flags, binary.

HVN May 6, 2006 14:10

Re: "Memory too low" problem with Fluent HELP NEED
 
256 Mo of RAM isn't enough for your case: remember that Win XP need at least 256 Mo. I recommend you to upgrade your RM up to 1 Go.

Adriano May 8, 2006 03:05

Re: "Memory too low" problem with Fluent HELP NEED
 
I guess Arm, I think, according to HVN, that your problem is only in your pc's Ram. If checking in both fluent and gambit did not give any problems the only way is update your hardware!

GoodLuck, Adriano

Amr May 8, 2006 06:33

Re: "Memory too low" problem with Fluent HELP NEED
 
Adriano / HVN,

I was working last couple of days on reducing my grid elements. I reached the following: when I had around 127000 elements, fluent was running fine but too slow (i.e. the time per single iteration was 4 min !)and this is frustrating in my case as I am performing unsteady calculations. When I reduced the mesh further to 63000, the fluent is running very fine. Having done that, now, I need to share with you how is the best way to adabt my grid. In my last 63000 elements, the grid spacing in allover the hall is 0.5 m. Remember that my hall is (14W x 27L x 18H). Any ideas?

Amr

Adriano May 8, 2006 12:06

Re: "Memory too low" problem with Fluent HELP NEED
 
Maybe, u can start with a mesh like your last one and then, when u join your better solution, try to adapt your mesh by fitting the original one using adapt section o fluent. in this way u should optimize your mesh cos u'll add more cells only where it needs.

sorry for my english I hope u understand me!:)

Adriano


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