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Flow between concentric cylinders
Posted Mar 25, 2010, 7:04 p.m. EDT 3 Replies
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Hi everyone
My name is Nader and I switched from FLUENT to COMSOL for my research and I am trying to learn it, I am working on modeling of fluid between two concentric cylinders but I dont know how to solve it, I used different models with different tolerance numbers but it gives me the same answer that FAILED TO FIND THE SOLUTION, how should I find out which one of these models are good for what?
cheers
My name is Nader and I switched from FLUENT to COMSOL for my research and I am trying to learn it, I am working on modeling of fluid between two concentric cylinders but I dont know how to solve it, I used different models with different tolerance numbers but it gives me the same answer that FAILED TO FIND THE SOLUTION, how should I find out which one of these models are good for what?
cheers
3 Replies Last Post Sep 22, 2010, 2:49 p.m. EDT
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Posted:
1 decade ago
There is a flow example in models of comsol (multiphysics->fluid dynamics)
usually relative set to 0.001, and abs set to 1e-4 (0.1mm) should work. you should also have enough fine mesh too.
usually relative set to 0.001, and abs set to 1e-4 (0.1mm) should work. you should also have enough fine mesh too.
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Posted:
1 decade ago
and one more thing: ramp your in flow in transient flows using flc2hs function on the inlet boundary. this way you relax the solver.
you can also use steady-state solution as the initial state too.
you can also use steady-state solution as the initial state too.
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Posted:
1 decade ago
Hi
When I use rotating velocity of 0.001[1/s] for inner cylinder it works quite well but when I increase the rotating velocity it start to diverge. unfortunately, i couldnt implement correct smoothing function for boundary condition.
Vx = w*y
Vy= -w*x
these are the boundary conditions and i dont know how to use smoothing functions like flc2hs for this case for the case of having a wave or heaviside function it works well but not for here.
When I use rotating velocity of 0.001[1/s] for inner cylinder it works quite well but when I increase the rotating velocity it start to diverge. unfortunately, i couldnt implement correct smoothing function for boundary condition.
Vx = w*y
Vy= -w*x
these are the boundary conditions and i dont know how to use smoothing functions like flc2hs for this case for the case of having a wave or heaviside function it works well but not for here.