[aspect-devel] Zhong et al. (2008) topography and geoid benchmark

Wed Jan 25 02:05:58 PST 2017

Hi everyone,

Thanks for the replies! Scott I haven’t tried out the benchmark or the bussinesq approximation so I don’t have any constructive suggestions for you yet, but it seems like another pair of eyes on this can’t hurt. I will look into the Zhong Stokes flow benchmarks (for topography and geoid) and see how far I get!
Thanks for offering computing time for this John! The resources I have should be enough but if not it’s great to know this is an option.

Best,
Jacky

PS: Due to an email screwup on my side Shangxin's email on this wasn’t part of the thread so I’m pasting it here:

Hi Jacky and Ian,

Last Month I found that my geoid code may still have bugs because I failed to reproduce the geoid with the same rheology from CitcomS. I already confirmed that my topography part has no problem (same as the output grid topography when computed back from spherical harmonics) but the density integral part still needs to be tested and I'm working on this now, also including reproducing the geoid kernel in Zhong et al. (2008) paper. I'd like to also try one calculation with the newly merged true boussinesq approximation after I update my ASPECT code. I haven't benchmarking the topography calculation with the paper. That's of course also a worthwhile work.

There is no essential change in my geoid code on github. I only add some extra output such as splitting the density and topography contribution in my own code. If you need this, I can further update it.

Best,
Shangxin

_________________________________
Jacqueline Austermann
Newton International Fellow
Department of Earth Sciences
University of Cambridge

www.people.fas.harvard.edu/~jaustermann<http://www.people.fas.harvard.edu/~jaustermann>

On Jan 24, 2017, at 9:39 PM, Scott King <sdk at vt.edu<mailto:sdk at vt.edu>> wrote:

I responded to Jacky and not to all.  We’ve tried the Zhong problems again (post 12/31/16) with the new Bousinessq model, and the results are not quite as good as previous (the mystery continues).  I don’t know if there is something we have not thought about that is a trick here.  We use the simple model and the case we are looking at is constant viscosity, so...  We went back to all parameters = 1 and gravity=Ra.   I don’t know if we should be using alpha = 10-2 and gravity=Ra*1e2 with the Business model.   I would have thought not.  Grants Bousinessq  results are not as good as the original version with alpha = 10-2 and gravity=Ra*1e2   We’ve noticed no real benefit to being dimensional either.

Grant is presently trying the Davies et al cylindrical benchmarks (with the distributed prm file) just to confirm his newly built version of Aspect will reproduce those results.

I notice some parameters that look like they are dealing with convergence in the Davies et al prm file that is included in the distribution.   Is there any insight on those?   I don’t have the source on the machine I have e-mail so I can’t send.  Thought this might ring a bell.

Best,

Scott

On Jan 24, 2017, at 4:10 PM, Rene Gassmoeller <rene.gassmoeller at mailbox.org<mailto:rene.gassmoeller at mailbox.org>> wrote:

As far as I recall there have been several tries to reproduce the time-dependent setup of this benchmark, but without the option to solve the exact boussinesq approximation we always had trouble to reproduce the vrms velocity to better than 5% or so. The most recent and extensive try was done by Scott and Grant Euen (presented at Grant's poster at AGU). I am not sure if anyone tried the Stokes flow / topography / geoid setup though, at least I did not, and I agree with John it might be very useful to have those.

Best,

Rene

On 01/24/2017 11:31 AM, John Naliboff wrote:
Hi Jacky,

I don't recall that benchmark being done with ASPECT, but it would indeed be great to do it.  If access to computing time for some of the high resolution runs would be helpful, just let me know and we can get you access to the CIG resources on STAMPEDE.

Cheers,
John

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

On 01/24/2017 02:17 AM, Jacky Austermann wrote:

Hi group,

Has anyone done / tried the Zhong et al. (2008) G3 benchmarks for surface and CMB topography? If this hasn’t been done and people think it’s worthwhile I’d be happy to give it a shot. This might also be a possibility to test the geoid post processors that people worked on during the last hackathon. Ian and Shangxin, if you’re willing to share I could test your geoid post processors (just let me know if the ones that are on your github repositories are up to date or update them if they aren’t).

Cheers,
Jacky
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