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How to add a mass source term to NS equation
Posted May 2, 2016, 5:08 p.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD) Version 4.3a, Version 5.2 2 Replies
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Hello everyone
I have a problem in adding a mass source term to the NS equation. I use it to account the mass loss due to vaporization during laser melting process. Currently I use the interface moving speed based on mass flux in the moving mesh module. But I'm not sure if it works properly.
Previously in V3, I can easily add the source term to the NS equation in the equation system.
But in the current V5 or V4 COMSOL, I cannot find the equation system, or any method to add a weak contribution to the continuity equation.
Do you have the solution? Thank you very much for your help.
I have a problem in adding a mass source term to the NS equation. I use it to account the mass loss due to vaporization during laser melting process. Currently I use the interface moving speed based on mass flux in the moving mesh module. But I'm not sure if it works properly.
Previously in V3, I can easily add the source term to the NS equation in the equation system.
But in the current V5 or V4 COMSOL, I cannot find the equation system, or any method to add a weak contribution to the continuity equation.
Do you have the solution? Thank you very much for your help.
2 Replies Last Post May 2, 2016, 5:56 p.m. EDT
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Posted:
9 years ago
Click the View button, and select "Equation View", per COMSOL Multiphysics version 5.2 Reference Manual page 165.
Best,
Jeff
Best,
Jeff
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Posted:
9 years ago
Thank you for your rapid response.
I found the weak form of the continuity equation in the laminar two phase flow, moving mesh module.
The form is as below.
test(p)*(-tpfmm.rho*tpfmm.divu-u*d(tpfmm.rho,x)-v*d(tpfmm.rho,y)-d(tpfmm.rho,TIME)+d(tpfmm.rho,x)*d(x,TIME)+d(tpfmm.rho,y)*d(y,TIME))
I can simply add a mass term with the test function in the end, right ?
One thing I could not understand is that why it starts with the shape function test(p), which denotes the pressure.
And one more thing is that whether the mass flux at the fluid-fluid interface contributes to the mass transfer or the mass loss during process. If so, the modification of continuity equation is not necessary. I understand that it indeed contributes to the mesh moving velocity at the interface, but not sure for the mass loss.
I found the weak form of the continuity equation in the laminar two phase flow, moving mesh module.
The form is as below.
test(p)*(-tpfmm.rho*tpfmm.divu-u*d(tpfmm.rho,x)-v*d(tpfmm.rho,y)-d(tpfmm.rho,TIME)+d(tpfmm.rho,x)*d(x,TIME)+d(tpfmm.rho,y)*d(y,TIME))
I can simply add a mass term with the test function in the end, right ?
One thing I could not understand is that why it starts with the shape function test(p), which denotes the pressure.
And one more thing is that whether the mass flux at the fluid-fluid interface contributes to the mass transfer or the mass loss during process. If so, the modification of continuity equation is not necessary. I understand that it indeed contributes to the mesh moving velocity at the interface, but not sure for the mass loss.