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cannot be convergenced or division by zero
Posted 26.08.2016, 18:41 GMT-4 0 Replies
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Now I am using COMSOL 5.0 to calculate mantle velocity field and thermal structure beneath mid-ocean ridge combining creeping flow node and convection-diffusion equation.
In my model, the viscosity is related to the temperature and spatial gradient of the velocity.
I first calculated the mantle flow and temperature for a constant viscosity. Then I use the strain rate and temperature from the initial solution to calculate viscosity values and solve the combined equations described above. Then I iteratively increased the maximum viscosity from 1e19 to 1e23.
While the solution cannot be converged at a viscosity value higher than 1e22.
The problem is 'division by zero'.
I changed the direct solver to iterative solver, and use constant Newton nonlinear method, the solution cannot be converged. If I use automatic Newton nonlinear method, the solution can be converged, but the results is wrong.
Could you give me some suggestions to solve the problem?
Many thanks,
John
Hello John Zhang
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