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Old   July 13, 2006, 14:40
Default About productivity in CFD
Production CFD Consultant
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How would you define productivity in the context of cfd?

For example when I have been using cfx I had a process that allowed me to run a lot of cases and then analyse trends from many calculations. In fluent I charge a consulting project more because the licenses are more expensive. However my analysis is based on less simulations and less information as you spend a lot of time clicking in fluent, especially for post-processing. I also have less time to do verification on different turbulence models.

Some people do their analysis based on 1 run.

Although it hard to be entirely focus on the number of runs, I am not sure having a low productivity in terms of simulations is good either.

Where is the middle ground according to you?

Prod. CFD

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Old   July 14, 2006, 09:42
Default Re: About productivity in CFD
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How many runs do you need to be "productive"? This question cannot be answered generally, because it depends on multiple parameters. Here is one consideration:

If "Some people do their analysis based on 1 run" that could be either completely nuts or quite appropriate in two different scenarios. If you're using an unfamiliar code to solve a new problem for the first time, it would be irresponsible to rely on a single run. However, if the problem is recurring, with relatively minor changes to problems you have previously solved, and if you are very familiar with the code, "1 run" may well be enough.

Considering this, it is obvious you're much more productive when your work is supported by extensive experience (with both the code and the flow problem), so you can concentrate on new details. If there is no such experience, because the new problems are radically different, and your work with a less familiar software is not streamlined, then you'll have to spend more time on it.

I guess the clue is to increase productivity along with skills and experience.
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Old   July 14, 2006, 14:30
Default Re: About productivity in CFD
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I agree with Mani. This is more of a side note.

If you're doing the same thing repeatedly in Fluent, then there are different ways of being able to automate the process. If it's a complex calculation you're looking for, there are UDFs. If it's something that Fluent will automatically put out for you (forces, surface averages, images, etc), then you can use journals (or batch scripts... same thing, just batch scripts implies that you're running Fluent without any interaction, where Journals are more like macros, where you tell Fluent when you want to run it) or you can even execute a command every so-many-iterations.

If you're looking for info on this, get involved in the Fluent forum.

Hope this helps, and good luck, Jason
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Old   July 14, 2006, 14:54
Default Re: About productivity in CFD
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what about return on investment? you need to get or save some money from using the license? how much do you need to use the code for this. Fluent is expensive and as said before the process is tedious (lots of clicking) so it is hard, but the cfx guys might be being had because fluent/cfx is a two-speed company now. Is it better to drive in dear car or the truck?

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Old   July 15, 2006, 09:10
Default Re: About productivity in CFD
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I think that in a way the productivity of the CFD itself is really immaterial. What counts is the progress and success of the project or design itself, and CFD is just a part of that system. So the question is how you can best hook CFD into the design process so that the design process benefits the most. In my experience, when the design and CFD practitioners are either the same person, or work very closely together, CFD becomes a very productive part of the process. The more you distance the CFD from the design process, the less productive it becomes. So as an outside contractor it becomes that much more difficult to be "productive", whatever that may be. But many organisations cannot afford to spend what it takes to build up a meaningful in-house capability, so they have to farm the CFD work out. "Buying CFD answers" from an outside contractor is IMHO very expensive and inefficient, so the trick is to integrate the temporary CFD contractor into the design process, but this is much easier said than done, and tends to conflict with a lot of corporate culture.
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