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-   -   DO NOT WAIT TIME ON EXA POWER(LESS)FLOW (http://www.cfd-online.com/Forums/main/11053-do-not-wait-time-exa-power-less-flow.html)

Is known as Mr CFD at my workplace March 21, 2006 10:48

DO NOT WAIT TIME ON EXA POWER(LESS)FLOW
 
I've been doing CFD for a number of years. My experience taught me that if something sounds too good to be true - then it normally is not true ! One example I can think of is EXA Powerflow - sold as revolutionary, effectless, 21 century (at one stage, even no need for turbulence models)bla bla bla...... It turns out powerflow is only powerful for generating pretty pictures (GENERATING UN-PHYSICAL EFFECTS AS SIDE PRODUCT). Exa salemen are the worse liars I ever came across - DO NOT BELIEVE A WORD THEY SAID - COMPLETELY WASTE OF TIME !

Jonas Larsson March 21, 2006 11:12

Re: DO NOT WAIT TIME ON EXA POWER(LESS)FLOW
 
Oh, that is interesting to hear, I was under the impression that Exa was doing quite well now, especially in the automotive sector. Many car manufacturers have started using Exa in the last couple of years. Have you run Exa in any benchmarks against other more traditional CFD codes?

pc March 22, 2006 08:05

please elaborate
 
If you're going to bad mouth a product you should at least provide some details supporting your statements.

What were you trying to simulate? Were you comparing with analytic results? Solutions from other codes? What were the "un-physical effects" you observed?

Makaveli March 22, 2006 09:45

Re: please elaborate
 
This view seems to be one that's been around for a long while now (doing a quick search of this site) with a lot of bad mouthing going on and it does seem that the sales people at EXA have told a few (well maybe allot) of mis-truths. But as Jonas has stated powerflow seems to have found a niche market in external automotive aerodynamics with companies such as BMW, karmann and Volkswagen-Audi group using it. I have read an internal report from VW on the development of the Phaeton comparing results gained with powerflow with wind tunnel testing, the report showed a strong correlation between the tests and the CFD (sorry can't say too much more due to confidentiality agreements). I believe the reason for this is the complex geometry prevents powerflow from poorly predicting separation (a problem I understand it suffers from - again from this forum).

I have not used the software myself as I cannot afford to buy a licence for a second CFD code (I am currently using Fluent) but it is my belief that powerflow seems suitable for the niche it has found. It also has some very interesting features, including a very easy meshing system and although the "21st century CFD" seems a little rich, a Boltzmann Lattice solver is a an interesting addition to the CFD community. Maybe given as much development time as the current crop of FVM and FE solvers it will become just as multi-purpose, providing reliable results for a number of situations.

As pc said can you elaborate on your problems with powerflow as this is an area of interest to me. I have read "Evaluation of PowerFLOW for aerodynamic applications" (http://research.nianet.org/~luo/journal-pubs.html) and I am aware of the problems outlined in it but this paper is a little old now so some more information regarding newer versions would be nice.


pc March 24, 2006 08:05

guess not
 
I guess he didn't have much more to add....

Makaveli March 27, 2006 09:40

Re: guess not
 
Looks that way. I was hoping for an interesting debate, but unsubstantiated accusations just amount to tabloid-esque slander, not debate. Shame

anonymous April 6, 2006 22:13

Re: DO NOT WAIT TIME ON EXA POWER(LESS)FLOW
 
Unfortunately CFD has become a commodity and many sales managers are under tremendous pressure to make numbers each quarter. In may experience CFD shopping I have found the Fluent staff most reputable (mostly PhD, CFD literate). The less sophisticated the product the less sophisticated the sales staff. CFdesign sales staff are by far least trustworthy and product is junk. If the sales person is not an engineer by training beware.

guang ai April 13, 2006 07:42

CFdesign? *NM*
 


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