[aspect-devel] Difficulties with tracers and material model

[Eric Heien]

Hi Adriaan,

I wrote the tracer code so I can answer any questions about that.  The tracer code does abort if particles fall out of the mesh since it assumes the system is closed in terms of mass.  If CFL>1 then it's entirely possible for a particle to move past the boundaries of the model but it seems this would also cause other problems with the model.  If you want particles to be able to fall out of the system without causing an abort, you can comment out the AssertThrow in check_particle_count() but you should make sure this is the correct behavior for your model.

Good luck,

-Eric

On Jun 7, 2013, at 4:31 AM, A.B.M. Graas wrote:

> 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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