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failed to evaluate variable, failed to evaluate expression, division by zero

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The error messages "failed to evaluate variable", "failed to evaluate expression", and "division by zero" can occur when you add a *new* physics node to a model that you have already solved and then you try to re-solve.
The problem can be that earlier you have set the following in your solution node:
Values of Dependent Variables > Initial values of variables solved for
Method: solution
Study: study 1 (for example)
Selection: Automatic

The errors are coming since COMSOL is looking for "initial conditions" for the new physics variable to come from the stored solution, which doesn't contain any information on the new physics variables that have just been added to the model.

One solution is therefore to set
Method: Initial expression
Study: Zero solution
Then COMSOL will be able to solve the model including the new physics node that you have added.
-DW

0 Replies Last Post 12 gen 2015, 13:24 GMT-5
COMSOL Moderator

Hello DW

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