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-   -   Which CFD program is more economic for small airplane use? (http://www.cfd-online.com/Forums/main/170-cfd-program-more-economic-small-airplane-use.html)

Lans September 9, 1998 08:33

Which CFD program is more economic for small airplane use?
 
Can any one give any information about CFD code more economic for small project use? some of them too expensive for small project use. Thanks

Sven Keski-Seppälä September 10, 1998 04:21

Re: Which CFD program is more economic for small airplane use?
 
Lans wrote : "Can any one give any information about CFD code more economic for small project use? some of them too expensive for small project use. Thanks"

This is a very simple and straigthforward question (and rather common I would say). Unfortunatley, there are no simple answer to it :( (I will not pretend to have the answer anyway :)

However it raises several other questions.

What is it that the CFD code should contribute with ? (estimations of aerodynamic coefficients (input to flightmechanics), predictions of fluid phenomena (vortex, transition ...), increased understanding of existing knowledge (e.g. explain EFD results, flight test results ..))

What are the options if we do not use CFD ? (experience, rule of thumb, EFD, flight tests, trial and error ...)

How badly is the information needed ? How accurate must it be ? How should we preceede if the information not is available ? To what extent do we accept uncertanies, that is, what risks (for (sub)project failure) are we accepting ?

Come so far in the discussion, it should exists a 'price tag' for the option of NOT using CFD. Given that cost, the costs of using CFD for the same problem should be investigated. Simultaneously, the (expected) accuracy and reliability of the planned CFD simulation with the given CFD code (solver/approach) must be considered. If we have an CFD-software with costs (not only for buying/license but also for introduction costs (education and hardware)) that (supposedly) meet the requirements of accuracy and reliability, well, we have a candidate :)

Naturally we also have to consider the time aspect :)

Well, that was my thougts on this matter. I will with interest read and consider any other response to this question. Especially, I will reflect on the arguments that are used for advocating in any particular software direction :)

Best regards Sven

PS, sorry if my english is broken and if I do not use the appropriate CFD nomenclature :)

John C. Chien September 10, 1998 09:24

Re: Which CFD program is more economic for small airplane use?
 
Assuming that the software is free ( it's really possible, if you are working in a school environment. Most of time, a big discount is available.) and assuming that the wind tunnel time is free ( it might not be possible because it requires a lot of energy- electricity.) , we still don't known whether we can design or analyze a small aircraft or not. ( There is a book on aircraft configuration design by AIAA series.) The issue is not the " free software " but the " free consulting help ". In addition to the free software, it also requires computer hardware. ( workstations through super-computers ). The possible answer is to look for educational CFD software available for PC environment first. There you may be able to get a big discount. As for the small airplane project, if you can get the software developer interested in your problem, then the problem will be largely solved. ( remember that the software itself is not very useful, it is only a binary record of a small amount of human activities in solving equations related to fluid dynamics.)

Bambang I. Soemarwoto September 13, 1998 21:14

Re: Which CFD program is more economic for small airplane use?
 
You might want to take a look at Public Domain Aeronautical Software (PDAS). Their web site is www.pdas.com

regards, Bambang


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