Courant number infinity
Hello Everyone!
What could be the reasons/causes why the Courant number is infinity? In pratice, what steps do you suggest to do in order to fix this issue? Thanks! |
The courant number can be roughly defined as U dt/dx. Thus, generally speaking, as long as you used a mesh with cells of finite dimension dx and a finite time step dt, the only reason for an infinite courant number is the divergence of the field U. This is the best one can say without any further information.
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Thank you for the reply! I am trying to debug my simulations since I get a courant number of infinity, but the time step is finite, and the cells have finite dimensions too. So I guess the problem is the divergence of U.
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Thanks. May I ask how can I check that the elements of the mesh have a finite dimensions? I am using GMSH, and it provides the gamma value (ratio between inscribed radius and circumscribed radius). This value ranges between 0.2 and 1 in my mesh. Is it enough to say that the elements have a finite dimension? I am trying to improve the mesh, and in some cases I also get Courant number of -1, but I can't explain why.
Thank you! |
First of all, what is the software? Are you aware about the way the CFL is computed? Check that all volumes are positive quantities.
However, you could simply experiencing a numerical instability, what about the velocity field? |
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