Divergence

aPostrophic · February 20, 2011, 07:37

Could anybody tell me what die fvm::div(phi,U) scheme is doing in OpenFoam?

Is div(-phi,U) the same as -div(phi,U) ?

akidess · February 21, 2011, 06:56

I suggest having a look at the Programmers Guide (P-38ff).

aPostrophic · February 21, 2011, 08:38

I read it already, but it does not help me.
According to the Programmers Guide -fvm::div(phi,U) und fvm::div(-phi,U)
should make no difference, but in my case it does.

eugene · April 5, 2011, 20:13

It depends on what convection scheme you are using. If it is symmetric (linear or harmonic) it shouldn't make a difference. If it is upwind or downwind biased, adding the minus will obviously switch the bias direction to the other cell bordering the face.

February 20, 2011, 07:37	Divergence	#1
aPostrophic New Member Join Date: Jan 2011 Posts: 6 Rep Power: 15	Could anybody tell me what die fvm::div(phi,U) scheme is doing in OpenFoam? Is div(-phi,U) the same as -div(phi,U) ?

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February 21, 2011, 06:56		#2
akidess Senior Member Anton Kidess Join Date: May 2009 Location: Germany Posts: 1,377 Rep Power: 29	I suggest having a look at the Programmers Guide (P-38ff).

February 21, 2011, 08:38		#3
aPostrophic New Member Join Date: Jan 2011 Posts: 6 Rep Power: 15	I read it already, but it does not help me. According to the Programmers Guide -fvm::div(phi,U) und fvm::div(-phi,U) should make no difference, but in my case it does.

April 5, 2011, 20:13		#4
eugene Senior Member Eugene de Villiers Join Date: Mar 2009 Posts: 725 Rep Power: 21	It depends on what convection scheme you are using. If it is symmetric (linear or harmonic) it shouldn't make a difference. If it is upwind or downwind biased, adding the minus will obviously switch the bias direction to the other cell bordering the face.