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MaxCo with interFoam

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Old   January 5, 2009, 04:39
Default Hello again. Thinking about
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Sebastian Gatzka
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Hello again.

Thinking about the maxCo entry in controlDict I'm asking myself what this entry is good for if I'm using Euler implicit discretisation for the temporal derivative, which should be unconditionally stable for ALL timesteps.

What is maxCo limiting in this case?
The velocity field?

Greetings.
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Old   January 5, 2009, 07:36
Default Hi Sebastian, yes, maxCo is
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Hi Sebastian,

yes, maxCo is based on the velocity field. The stability is limited by the PISO algorithm, which is stable for Co up to 1 i think. But Co should be lower for interFoam, it should be around 0.25. To overcome this, you can use subtimestepping for MULES. A good choice is maxCo = 0.5 and two subtimesteps for gamma.

Concerning Euler: even if Euler is unconditionally stable, this does NOT mean that it is unconditionally accurate ;-)

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Old   January 6, 2009, 04:05
Default Thank you, Christian. That mak
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Sebastian Gatzka
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Thank you, Christian. That makes sense.
Who can tell the correct Co-limit for PISO?
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