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May 9, 2004, 17:57 |
about the discretization of unsteady term
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#1 |
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Hi..everyone..
I have question for the unsteady methods. one is three time level method, another is Adam-bashforth methos. Usually, the most of LES is using the adams-bashforth method for the convection terms and the Crank-Bicolson for the diffusion term. I'm making code for LES using three-time level method(SIMPLE scheme is used) What's the difference three time level and Adam-Bashforth ones? Does have any problems if I use the three time level methd in SIMPLE for LES code? If it is wrong, How to apply the adams-bashforth method to SIMPLE scheme? Thank you for your concerned |
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May 10, 2004, 13:01 |
Re: about the discretization of unsteady term
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#2 |
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Crank Nicholson is a single step implicit scheme.
Adams Bashforth is a multi-step scheme, which reads as, u_n+1 = u_n + 1/2*(3*u_n - u_n-1) I don't know what is a three time level scheme. Most likely, it is a three step scheme (possibly BDF) or a three stage Runge Kutta, (which can be second order accurate at best). You can find details of such schemes in any numerical book on ODEs. I recommend: E Hairer, SP Norsett and G Wanner, Solving ordinary differential equations, second edition (2 vols.). But it may be too advanced for beginers. Hope this helps. |
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