[aspect-devel] Difficulties with tracers and material model

[A.B.M. Graas]

Hi there,

Quick introduction; my name is Adriaan Graas and as a bachelor student I
perform geodynamic benchmarks with ASPECT at the University of Utrecht. I
am very impressed with the possibilities of ASPECT, however there are some
problems I run into.

- Running particle tracers crash with the message "Particle count
unexpectedly changed". This happens mostly when timesteps are large (CFL
number is large). I suspect that the tracers postprocessor might not be
ready for particles leaving through velocity boundaries?

- In many of my models I model plasticity by using a Material Model
implementing the new Interface. Often, though not always, there are
unexpected irregularities (viscosity jumps) in the corners. I found  that
the evaluate() method of the Material Model is never called with a position
Point in the corners before the Stokes equation is solved. However,
afterwards the evaluate() method is called by the Viscosity postprocessor.

- If "Max nonlinear iterations" and/or "Nonlinear solver scheme" is set in
the input file, one is not able to turn off the nonlinear iterative solver
by setting "Nonlinear iteration" to false.

Please don't hesitate to ask for input files or additional explanation.

Thanks in advance,

Adriaan Graas
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