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Old   January 10, 2002, 14:25
Default FEM vs FDM
  #1
Jack
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Can we use FEMs for flow analysis?
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Old   January 10, 2002, 16:38
Default Re: FEM vs FDM
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andy
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Yes.
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Old   January 10, 2002, 18:23
Default Re: FEM vs FDM
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P.Fonteijn
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Discontinuites, like shocks, are hard to describe. And, don't expect any speed up compared to FDM. FEM is as slow as FDM.

Pascale
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Old   January 10, 2002, 22:18
Default Re: FEM vs FDM
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cfd user
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There are many existing commercial codes which use FEM as their discretization. It will tend to be slower as mentioned in another response but literature shows it to be more accurate, requiring less grid points then FDM or FEM. Links between a FEA solver and CFD solver can be made with the finite element technique. It will probably be the way some day.
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Old   January 11, 2002, 01:40
Default Re: FEM vs FDM
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Ist
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Dear all,

How about with FVM ? I think it is more stable solution compared with FDM. But, what's your comment ?
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Old   January 16, 2002, 17:31
Default Re: FEM vs FDM
  #6
kenn
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if it's an old FEM software, I guess it can't solve convetion dominating flow problems very well, because of stability issue.

but in fluid mechanics, todays' finite element kind methods are much better than FDM
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Old   January 16, 2002, 17:48
Default Re: FEM vs FDM
  #7
kenn
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all FEM, FDM, FVM, and spectral element methods are special forms of weighted residue methods. none of them are better method for every problems. by logic, FV must have disadvantages. it's stable due to it's local control of conservation, which is obviously better than global control; it treats complex gemotry much better than FD, which has to use boundary fitted coordinates or transformation to another space(computational space). so, FV is a general-purposed method. so why still FD?

I guess, for many problems, FV lacks accuracy.

FD could converge much faster than both FV and FE for many problems.

Spectral element converges even faster, however, in each step it costs more time to do integration( I guess) something like that.

also, FD is the easiest method to implement. BEM(boundary element) is the fastest method.

so, I'll say, if a problem can be solved using FD or BE gracefully, then use them; otherwise, consider the other three methods.
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Old   January 17, 2002, 09:11
Default Re: FEM vs FDM
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Herve
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Look at the book edited by 33. Wendt, J.F., (1996), "Computational Fluid Dynamics – An Introduction", Springer. or the paper by Idelsohn, S.R., Oņate, E., (1994), "Finite Volumes and Finite Elements: Two 'Good Friends'", Int. J. num. Meth. Eng., Vol. 37, pp. 3323-3341. for a comparison. the advantage of FVM is that it is easy and fast to compute, and mass conservative (something more difficult to achieve with FEM I believe).
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Old   January 18, 2002, 19:13
Default Re: FEM vs FDM
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Scott
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www.cfdesign.com
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Old   January 21, 2002, 03:04
Default Re: FEM vs FDM
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Ist
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I think those method (FEM, FDM and FVM) has disadvantage and advantage. No method has not disadvantages. Ok
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Old   January 27, 2002, 11:42
Default Re: FEM vs FDM
  #11
yangqing
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now is FVM , one fdm method
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