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December 2, 2012, 08:41 |
Passive Scalar boundary conditions
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#1 |
New Member
Francesco
Join Date: Dec 2012
Posts: 3
Rep Power: 13 |
Hello,
I am performing a simulation of the advective-diffusive mass transfer for the oxygen in a fluid. I have a bifurcating pipe (an artery and a vein), with a velocity inlet, a velocity outlet, and a pressure outlet as boundary conditions. I'm using the passive scalar model to simulate the oxygen, and I would like to impose the normal concentration gradient, on the two outlets, but since I'm using a velocity and a pressure as boundary conditions, I can only impose a specified value on those faces. For what concerns the other boundaries, I have a concentration sink on the wall of the pipes (with a specified value of 0), and a constant concentration on the inlet. I have also tried to use the flow-split condition, but sometimes the solution start diverging because of a recirculation on the cells of the boundary layer, even if I try extend the pipe to damp the recirculation. The Schmidt number I'm using is quite high (2700), and I noticed that if I change the constant value on the outlets from 0 to 1 the solution for the passive scalar remains the same, on the other hand, imposing the gradient would be conceptually more correct. Does anyone have any suggestion? Thanks in advance, Francesco |
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December 13, 2012, 04:15 |
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#2 |
Senior Member
siamak rahimi ardkapan
Join Date: Jul 2010
Location: Copenhagen, Denmark
Posts: 220
Rep Power: 18 |
I hope I understood correct. If you want to have a normal distribution of a phase (oxygen) you can use lagrangian multiphase mode. Then the second phase will be defined as a normal distribution.
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Good luck Siamak |
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Tags |
boundary condition, passive, scalar, schmidt, starccm+ |
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