Divergence or failure to converge in the nonlinear solution

Potential causes of divergence in the nonlinear solution include:

• taking too large of a time step. The initial guess is outside of the region of convergence for the Newton method.
• an incorrect system of equations.

Suggestions:

• Try taking a smaller initial time step or use -estimateInitialTimeStep.
• Turn on -useConvergeHeuristics.
• Carefully validate that the model is implemented correctly and that the systems of equations are well-posed. Too few boundary conditions (i.e. an underconstrained system of equations) can also lead to wandering and divergence.
• Try turning on -applyDamping. The damped Newton will likely converge very slowly, and this should be used only as a last resort.