Courant number explodes
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Hello Foamers!
i am trying to simulate the bifurcation that is depicted in the bifurcation.png file. There is one inlet in the right of the geometry and three outlets at the right. I use icoFoam to solve the flow problem. the deltaT is 1e-4. The courant number at first is very small but is increased with a small step after each iteration. After 10000 iterations the courant number is getting too big so the simulation stops. The mesh is ok after checkMesh. I calculate the Dp in order to have the desired mean velocity in the pipe before the bifurcation and then i divide with density. 0/p File object p; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField uniform 0; boundaryField { inlet { type fixedValue; value uniform 0.012957446; } outlet_internal { type fixedValue; value uniform 0; } outlet_externalbig { type fixedValue; value uniform 0; } outlet_externalsmall { type fixedValue; value uniform 0; } walls { type zeroGradient; } } 0/U File object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { inlet { type pressureInletVelocity; value uniform (0 0 0); } outlet_internal { type zeroGradient; } outlet_externalbig { type zeroGradient; } outlet_externalsmall { type zeroGradient; } walls { type fixedValue; value uniform (0 0 0); } } transportproperties transportModel Newtonian; nu nu [ 0 2 -1 0 0 0 0 ] 0.000002057; Can anyone help me to solve the problem ? I stuck over 15 days |
Hey
Why are you running a transient simulation for this case? |
I know that Poiseuille flow is treated as steady state.
But i have developed a code based on transient solver and i need to evaluate the results of my case with experimental data |
Ahh okay. Did you try running adjustable time stepping? Also, try pimplefoam solver : use higher outerCorrectors and relax the solution
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If you know the desired velocity at the inlet, just impose that, rather than the pressure at the inlet (it seems you use that to find the pressure drop?).
Also, as a suggestion, I would not recommend icoFoam. You could use pimpleFoam, and have better control on the solution process (outer correctors, adaptive time-step, under-relaxation, ...). |
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