[giack]

Hi to all
I want to know how is calculated AlphaCourantNo so I look for the code and I find this lines.

if (mesh.nInternalFaces())
{
scalarField sumPhi
(
pos(alpha1 - 0.01)*pos(0.99 - alpha1)
*fvc::surfaceSum(mag(phi))().internalField()
);

alphaCoNum = 0.5*gMax(sumPhi/mesh.V().field())*runTime.deltaTValue();

}

My understanding of this piece of code is that for each cell it sums the face flux magnitudes, divides it by the cell volume and multiplies it with deltaT/2. The maximum over all cells is then the Courant number.
But I don't understand the meaning of this term:

pos(alpha1 - 0.01)*pos(0.99 - alpha1)

Anyone kwon the meaning of it?
Thank to all

[pixarzhang]

Originally Posted by giack

Hi to all
I want to know how is calculated AlphaCourantNo so I look for the code and I find this lines.

if (mesh.nInternalFaces())
{
scalarField sumPhi
(
pos(alpha1 - 0.01)*pos(0.99 - alpha1)
*fvc::surfaceSum(mag(phi))().internalField()
);

alphaCoNum = 0.5*gMax(sumPhi/mesh.V().field())*runTime.deltaTValue();

}

My understanding of this piece of code is that for each cell it sums the face flux magnitudes, divides it by the cell volume and multiplies it with deltaT/2. The maximum over all cells is then the Courant number.
But I don't understand the meaning of this term:

pos(alpha1 - 0.01)*pos(0.99 - alpha1)

Anyone kwon the meaning of it?
Thank to all

I have the same question.Does anyone know the meaning?

[danieldeising]

Hi enzhen,
this line

pos(alpha1 - 0.01)*pos(0.99 - alpha1)

gives you all cells where the volumetric phase fraction takes
values between 0.01 and 0.99.
And this piece of code

0.5*gMax(sumPhi/mesh.V().field())*runTime.deltaTValue();

is the definition of the Courant number in multiple dimensions,
assuming that the calculated velocity field is divergence free.

So as a result, you obtain a Courant number in the interfacial area.

Hope this helps,

Best,
Daniel

[pixarzhang]

Originally Posted by danieldeising

Hi enzhen,
this line

pos(alpha1 - 0.01)*pos(0.99 - alpha1)

gives you all cells where the volumetric phase fraction takes
values between 0.01 and 0.99.
And this piece of code

0.5*gMax(sumPhi/mesh.V().field())*runTime.deltaTValue();

is the definition of the Courant number in multiple dimensions,
assuming that the calculated velocity field is divergence free.

So as a result, you obtain a Courant number in the interfacial area.

Hope this helps,

Best,
Daniel

thanks ~that does help