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-   -   Question about Fluent (http://www.cfd-online.com/Forums/fluent/28788-question-about-fluent.html)

Bill August 6, 2001 13:29

Question about Fluent
 
Why is Fluent the world's largest (no. of users) CFD code when it is clearly worse than both CFX and Star? The physices in Fluent are poor and if its anything complex the convergence is terrible.

True, gambit is easy to use, but not for complex files and CAD import is v bad and the adaption is a pain in the arse. Whats the point in getting a mesh if its so bad the answers are wrong.

I assume that it is just good marketing. Anyone have any ideas?

J.D. August 6, 2001 14:23

Re: Question about Fluent
 
It is important to remember that computer programs are only as stupid as the person that is operating them. Keep that in mind the next time you are pondering such deep, personal questions.


Scott Whitney August 6, 2001 14:50

Re: Question about Fluent
 
I've used both CFX and Fluent. To me, Fluent was easier to use. It was certainly cheaper to license (free to universities). And I got my converged results in half the time when using Fluent (maybe I was just not good at CFX).

Post processing was much, much easier on CFX.

So I guess the score is 3 points to 1 point. I no longer use CFX.

Ann August 6, 2001 15:57

Re: Question about Fluent
 
Fluent is not a better code with any stretch of imagination. It is a user friendly code and that seems to be 99% of the selling job. Once you get the code, and you have a slightly more difficult problem than a channel flow, then you would start to encounter problems. At that point, they start pushing consulting services on you. For them it is a win/win situation. They have wonderful marketting and agressive (and sometimes complacent) sales force, which the other guys don't have. They are much bigger now and can afford being arrogant (which they are). It is true that Gambit is easy to use, but it is also very deficient if you want to do complicated meshes. So I agree with you the mesh is usually bad and the answer is most of the time wrong, specially if you do a mesh refinement study, you will notice that convergence is really in the eye of the beholder. The physical models are plenty but lousy. If you have for example a low Re number turbulent flow, just forget it. The models are extremely poor. The code is so diffusive that will give you a fully convereged laminar solution where the flow is clearly turbulent. They pretend that they do validation studies, but that is also a marketting gimmick.

The real problem is that their competition is not as agressive as they are and they also don't have their act together.


Lou August 8, 2001 09:32

Re: Question about Fluent
 
Its interesting to see the difference between the answers here and on the main form.

My experience is that if its multi-phase then forget it. Gambit is easy to use, but thats no use when the mesh doesn't produce any answers.

Its true about the mesh adaption, it is very hard to use and takes a long time. I thought maybe the mesh was the problem but I couldn't even get it to work with pipe flow with my problem.

Maybe fluent want to comment on this. We hear all about their marketing machine, but they haven't commented.

Or perhaps they think its better not to say anything on this kind of debate?


John C. Chien August 8, 2001 12:46

Re: Question about Fluent
 
(1). About the mesh adaption, based on my experience, it works. I had studied this part of option extensively several years ago. That is, you can refine the mesh at the boundary, or you can specify a region. (there are also other options which are not frequently used) (2). From business point of view, I don't think any CFD company is interested in solving your problem at all. Since you are using their codes already,they want you to continue using the code in the future, and also have the opportunity to work on your problem. (3). So, "my theory" is, as long as your problem remains un-solved, everybody will have a chance to work on it. When it is completed, the opportunity is gone. (it will arrive sooner or later, they are not interested in rushing to the end) (4). To get the solution you want, you will have to say it clearly in the contract. But this is not easy task for CFD. (4). So, unless the investment will clearly bring more business to the vendors, there is no incentive for them to spend their research money ahead of the time.


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