How can I run underworld at desired resolution and apple a periodic boundary condition?

[QwZhang]

Hi all,
I have two problems when using Underworld (version 1.7.0).
(1) I find it's wired that when I run a 3D subduction model (similar to Capitanio(2011)'s configuration) at cell number of 96x64x96 (or 64x32x64, 96x48x96 or 128x64x128, etc.) in x-, y- and z- direction, respectively, at multigrid level of both 4 and 5 using 120 CPU cores on the supercomputer Tianhe-2, Underworld runs extremely slow, not even one step in one hour; while I try the same model with higher resolution (e.g., 192x64x192), Underworld runs well and the consumed CPU hours is about 5~10 minutes per step, which looks reasonable. So I have no idea why model with high resolution (e.g., #cell=192x64x192) takes much less CPU hours than the one with 1/8 or 1/4 of total number of cells (e.g., #cell=96x32x96). This is quite strange for a multigrid solver. I simply want to use #cell of 96x32x96, not 192x64x192, to get what I want without having to deal with much more output data and cosuming much more CPU hours.

(2) No-slip boundary condition is not the best choice in some case when redistibution of materials leads to space problem and thus yields realistic results. So how can I apply a periodic velocity boundary condition on the sidewalls of a box to allow inflow/outflow of the materials? I tried but failed to find an example of this type of bondary condition in the documents of Underworld.

Any instructions or hints will be appreciated.

Best regards,
Qingwen

Reference
Capitanio, F, et al, 2011, Subduction dynamics and the origin of Andean orogeny and the Bolivian orocline. Nature.

[jmansour]

Hi Qingwen. We've recently added a github repo for Underworld1:

https://github.com/underworldcode/underworld1

I've added your issue there:

underworldcode/underworld1#1

[QwZhang]

Okey, thank you very much for your reply.
Qw