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Inviscid Flow

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Hi,

I want to model a 2d inviscid flow in comsol v4.1, but when I set Dynamic viscosity=0 , I have some convergence problem.

It can be solved by using full Navier-Stokes Equations, but when I set the dynamic viscosity to zero, it does not converge.

should I use lower value instead of Zero?

what is the classic way of modeling the inviscid flow in COMSOL?


best

3 Replies Last Post 2014年2月26日 GMT-5 13:38

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Posted: 1 decade ago 2011年5月24日 GMT-4 12:27
any suggestion ?>?
any suggestion ?>?

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Posted: 1 decade ago 2014年2月26日 GMT-5 09:29
Hi, I have the same problem. Could you solve your problem?
Hi, I have the same problem. Could you solve your problem?

Eric Favre COMSOL Employee

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Posted: 1 decade ago 2014年2月26日 GMT-5 13:38
Hello,

Inviscid fluid is often (but not always) associated with irrotational flow theory.
If this applies to you, this is pretty straightforward in COMSOL :
since the flow is irrotational, you can write
u = grad (phi) (u derives from a potential phi).
together with mass conservation div (u) = 0
implies
laplacian (phi) = 0 (Laplace equation in COMSOL).
You only need to derive phi wrt space to get the velocity component.
Do not forget to think about the boundary conditions : a condition on u or v writes into a Neumann boundary condition for phi where you imposes n.grad (phi) = for instance d(phi)/dx = u along a vertical boundary.

Good luck,

Eric Favre
Hello, Inviscid fluid is often (but not always) associated with irrotational flow theory. If this applies to you, this is pretty straightforward in COMSOL : since the flow is irrotational, you can write u = grad (phi) (u derives from a potential phi). together with mass conservation div (u) = 0 implies laplacian (phi) = 0 (Laplace equation in COMSOL). You only need to derive phi wrt space to get the velocity component. Do not forget to think about the boundary conditions : a condition on u or v writes into a Neumann boundary condition for phi where you imposes n.grad (phi) = for instance d(phi)/dx = u along a vertical boundary. Good luck, Eric Favre

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