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cannot be convergenced or division by zero

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Hi guys,
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

0 Replies Last Post 26.08.2016, 18:41 GMT-4
COMSOL Moderator

Hello John Zhang

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