Hello, i am working in a sanitary company. Our Problem at our simulations with Flow 3D is that we often need very small cell sizes in our cartridges (0,25mm at nested blocks) and high flow velocities (up to 10 - 15m/s in these cells). So the time steps at transient analyses become very small. Using "automatic limited compressibility" and a higher "con" (0,65 - 0,75) helps to get a faster solution but the solution times are still too long. Currently we are in desicion which workstations we should buy for the future work with flow3d.

What are your opinions and experiences? Should we take a workstation with 8 cores (for example 2 Quadcore Intel Xeon with 3,16 GHz, 12 MB L2-Cache & 1333 MHz FSB) or 2 Intel® Xeon Dualcores? Alternatively is it better to use 2 Dual-Core AMD Opteron processors with AMD HyperTransport Technology at the bus system?

Currently we work with a Dual core intel xeon with 3,0 GHZ and a 1333 MHz FSB and the long solution times are not satisfying our requests.

Please help me to built a decision and thanks a lot for your efforts.

Best regards, Jochen

Intel is coming out with a new chip called Nehalem, which has similar NUMA type memory access as AMD currently does. Some of our benchmarks show that Intel processors are generally faster with FLOW-3D, than are AMD chips.

I'd go for 8 cores, although SMP scaling in FLOW-3D does not often go beyond 4 threads at the moment, but plans have been laid out to push it to 8 and 16 cores.

Whatever you decide to get, look for the fastest memory bus, good graphics, large disk space and... good processors!

Michael, thank you for your quick response,

because the new chip Nehalem is not yet available and at the moment not certified for our other CAE applications we will go to 2 Quadcores from intel.

Greetings, Jochen

Sounds good, Jochen. How do you certify new chips? Test it for speed and accuracy? Or just speed?

Michael

Nehalem is available for desktop machines now. The architecture is labeled "Core i7". You will be able to make use of all cores if you get any processor with Core i7. This architecture solves memory bandwidth problem in older "Core 2" processors.

http://www.intel.com/products/deskto...s_body+dt_core

AMD's Shanghai is a good alternative, if you are not able to procure the "Core i7" processor or if it does not fit your IT resource planning. They have a 6-core release planned in this year which you can use to upgrade keeping the old system as is.

Nehalem is certainly faster than Shanghai. Nehalem uses DDR3 memory which is faster than DDR2 memory used by Shanghai. You should budget for the more expensive DDR3 memory as well.

FLOW-3D is a memory Bandwidth limited application, with today's computer architecture.

Hello Michael, we don't certify the new chips in our company ourselvs. That was a little missunderstood. Because we use 4 other CAE codes beside Flow3D we only buy hardware which is certified from each software package.

Jochen