[aspect-devel] Van Keken et al. 2008 subduction benchmark

John Naliboff jbnaliboff at ucdavis.edu
Thu Oct 27 10:28:23 PDT 2016

Hi Max,

I haven't tried this benchmark specifically, but yesterday I tried a 
problem (GeoMod compression) with prescribed internal boundary 
conditions using the same plugin.

The internal velocity field I prescribed was quite simple compared to 
the subduction benchmark (uniform horizontal and vertical velocity), but 
time-dependent.  I had no solver issues when the internal velocity 
constraints did not vary with time, but immediately had solver issues 
once I incorporated time-dependence.

I'm not sure what the solution on my end is, but perhaps velocity-based 
mesh refinement (multiple initial refinement steps) in your case would 

As I recall, mesh refinement in at least Peter's code (SEPRON-based) 
helped minimize pressure oscillations in the region of the 
discontinuity.  Susanne Buiter's code (SULEC, no AMR) also has similar 
issues to what you describe below with this benchmark.


John Naliboff
Assistant Project Scientist, CIG
Earth & Planetary Sciences Dept., UC Davis

On 10/27/2016 09:13 AM, Max Rudolph wrote:
> I was wondering if anyone has been successful in setting up the Van 
> Keken et al. 2008 subduction benchmark using ASPECT? I have been using 
> this as a starting point to set up a more complicated corner flow 
> model and have not yet been successful.
> This benchmark solution requires a rigid overriding plate and 
> kinematic subducting plate. There is a discontinuity along the 
> subduction interface. I tried imposing kinematic boundary conditions 
> on the left and bottom of the box and using Jonathan Perry-Houts' 
> prescribed velocity plugin (cookbooks/prescribed_velocity), but the 
> Stokes solver fails to converge. Looking at the pressure field, it's 
> not surprising to see very large oscillations in this region where the 
> velocity field is discontinuous. It occurred to me that using the 
> locally conservative discretization might help. However, when the 
> locally conservative discretization is enabled, the internal 
> prescribed velocities are no longer enforced anywhere. Is it obvious 
> why this might be the case?
> Regards,
> Max
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> Aspect-devel at geodynamics.org
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