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Old   June 24, 2008, 12:14
Default Maybe a dumb question but... H
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John Deas
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Maybe a dumb question but... How is it that Fluent is capable of fully-implicit time discretisation while OpenFOAM is not ?
Or, if put another way, what would be required to have fully-implicit time discretisation in OF ?
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Old   June 24, 2008, 12:39
Default What do you mean by "fully imp
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Eugene de Villiers
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What do you mean by "fully implicit" time discretization, and why do you think there is a difference between Fluent and OpenFOAM in this regard?
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Old   June 24, 2008, 12:46
Default You would need to solve the eq
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You would need to solve the equations of mass, momentum and energy simultaneously instead of segregated.
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Old   June 24, 2008, 12:49
Default For example, you won't have li
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For example, you won't have limitation on your Courant Number in Fluent.

This question arised as the Courant number can be a limitating factor and force you to have timesteps smaller than the one required by the eddy dissipation time.
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Old   June 24, 2008, 13:11
Default Most of the time schemes in Op
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Eugene de Villiers
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Most of the time schemes in OpenFOAM are "fully implicit". There are probably other things that Fluent does to run stable at very high CFL numbers.

On the other hand I regularly run LES with maximum CFL numbers of 2-3 without problems. It depends on the solver and your limiters I guess.
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Old   June 24, 2008, 13:50
Default Sorry Eugene - time to read a
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Hrvoje Jasak
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Sorry Eugene - time to read a book. The guy is talking about a block solution of the compressible flow system, which is "more implicit" than the segregated solution you are used to.

This is coming with my new block matrix implementation.

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Old   June 24, 2008, 13:59
Default Hrv, "This is coming with my
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Xiaofeng Liu
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Hrv,
"This is coming with my new block matrix implementation"

When? I have been looking forward for this for a long time.
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Old   June 24, 2008, 14:37
Default As you may have guessed, it is
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Hrvoje Jasak
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As you may have guessed, it is all about funding: fully financed projects get priority, deadlines etc, meaning that interesting pieces of work get delayed.

It has been delayed for an inexcusable number of times, but it will make you happy to know that some people are already running block-coupled solutions.

Apologies for the delay,

Hrv
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Old   June 24, 2008, 14:46
Default We should thank you for develo
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We should thank you for developing such a great software!
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Old   June 24, 2008, 18:23
Default Great! Hrv I should also th
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Great! Hrv

I should also thank you for sharing.
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Old   June 25, 2008, 08:40
Default Dear Hrv I wondered if the
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Dear Hrv

I wondered if the community can enjoy such piece of work via the development version? This would be thankful news (among others).

Best wishes
Patricio
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