courant number

maysmech · August 27, 2010, 15:35

Dear Foamers,

What is the meaning of Co number in the pisoFoam for example.
what should be its range? is it important in implicit methods?
i know it is for stability. how much it can be large?
please talk about the role and magnitude of this number in solving methods.
Regards,
Maysam

akidess · August 30, 2010, 02:13

Read Peric or Patankar about the PISO method and you will see assumptions are made that require a Courant number limit. This is independent of the implicit / explicit time marching scheme. For an incompressible flow you should get away with Co < 1, but there are cases (eg. VOF) that may require an even tighter criterion to produce nicer results.

August 27, 2010, 15:35	courant number	#1
maysmech Senior Member Maysam Join Date: Jan 2010 Posts: 308 Blog Entries: 2 Rep Power: 6	Dear Foamers, What is the meaning of Co number in the pisoFoam for example. what should be its range? is it important in implicit methods? i know it is for stability. how much it can be large? please talk about the role and magnitude of this number in solving methods. Regards, Maysam

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August 30, 2010, 02:13		#2
akidess Senior Member Anton Kidess Join Date: May 2009 Location: Delft, Netherlands Posts: 765 Rep Power: 13	Read Peric or Patankar about the PISO method and you will see assumptions are made that require a Courant number limit. This is independent of the implicit / explicit time marching scheme. For an incompressible flow you should get away with Co < 1, but there are cases (eg. VOF) that may require an even tighter criterion to produce nicer results.