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Convergence problem in incompressible Navier-Stokes
Posted Aug 5, 2010, 8:16 a.m. EDT Microfluidics 1 Reply
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Hi,
I'm quite a rookie in using comsol and I'm experiencing some problems in microfluidics simulations.
Either if I use very simple circuits or more complicate ones I can't reach a correct solution with the numerical values I use because of convergence problems.
On the other hand if I put completely different values (for example the same used in tutorials) everything seems to work very well.
If you have any suggestion on how to solve this kind of numerical convergence problems, please help me.
Thank you,
Giovanni ACCETTA
Ps for instance I'm using the incompressible navier stokes model
UPDATE: the problem is mainly in the pressure which is high (~10^3) compared to viscosity and density of water as far as the dimensions of the channel. So I would need either a rescaling of the dimensions/constants or of the pressures used. But I don,t know how this will affect the resulting velocity field(which I should use in a convection and diffusion problems).
I hope someone can help me.
I'm quite a rookie in using comsol and I'm experiencing some problems in microfluidics simulations.
Either if I use very simple circuits or more complicate ones I can't reach a correct solution with the numerical values I use because of convergence problems.
On the other hand if I put completely different values (for example the same used in tutorials) everything seems to work very well.
If you have any suggestion on how to solve this kind of numerical convergence problems, please help me.
Thank you,
Giovanni ACCETTA
Ps for instance I'm using the incompressible navier stokes model
UPDATE: the problem is mainly in the pressure which is high (~10^3) compared to viscosity and density of water as far as the dimensions of the channel. So I would need either a rescaling of the dimensions/constants or of the pressures used. But I don,t know how this will affect the resulting velocity field(which I should use in a convection and diffusion problems).
I hope someone can help me.
1 Reply Last Post Aug 6, 2010, 1:21 p.m. EDT
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Posted:
1 decade ago
Just if someone get the same problem:
I solved it by simply changing the boundary condition on the inlets and outlets.
In fact even if in theory more stable the "pressure, no viscous stress" condition gave me problems, while I obtained the correct solution with the laminar inflow condition with proper lenght.
Thanks.
I solved it by simply changing the boundary condition on the inlets and outlets.
In fact even if in theory more stable the "pressure, no viscous stress" condition gave me problems, while I obtained the correct solution with the laminar inflow condition with proper lenght.
Thanks.