[CIG-LONG] cig-long email list
Eunseo Choi
echoi at ldeo.columbia.edu
Fri May 1 13:42:18 PDT 2009
Hi, Todd
Thanks for the suggestion.
I've thought about it and think it might be the only proper (not just
better) way of comparing two codes.
However, I've never succeeded in running Gale so far.
Also, maybe the comparison is meaningful to some degree if two systems
are not that different?
Eunseo
Todd Ehlers wrote:
> Hi Garrett and Eunseo
> If possible you might want to run both on the same hardware and compile both codes with the same compiler with the same optimization flags.
> . Cheers,
> Todd
> Sent via BlackBerry from T-Mobile
>
> -----Original Message-----
> From: Eunseo Choi <echoi at ldeo.columbia.edu>
>
> Date: Fri, 01 May 2009 08:39:51
> To: Garrett Ito<gito at hawaii.edu>
> Cc: Mark Behn<mbehn at whoi.edu>; <cig-long at geodynamics.org>
> Subject: Re: [CIG-LONG] cig-long email list
>
>
> Hi, Garrett
>
> I agree that our first order goal should be to compare performance.
> My model will have 150x45x6 elements and be made as similar to yours as
> possible in terms of initial/boundary conditions.
> I'll get back to you when I get results.
> Thanks.
>
> Eunseo
>
>
>
>
>
> Garrett Ito wrote:
>
>> Hi Enseo,
>>
>> Regarding your question about viscosity-- remember that Gale is a
>> purely viscous code so it simulates plasticity with variable,
>> strain-dependent viscosity (i.e., pseudoplasticity). As for the
>> benchmark, at this point I'm most interested in seeing whether the
>> two codes are comparable in speed (or shall I say "slowness"). What
>> will be most important at this point is that the plasticity law uses
>> generates localized zones of strains like faults. Yes, I can produce
>> a whole suit of 3D calculations with whatever number of elements in
>> the 3rd dimension, plus details on cpu #'s and compute times. I'll
>> start one soon with 150x45x6 (i.e., I think Gale will want at least 4
>> elements in the 3rd dimension). Lemme know how your side is coming
>> and we can work on details of the comparisons.
>>
>> Thanks,
>>
>> Garrett
>>
>> Eunseo Choi wrote:
>>
>>> Hi, Garrett
>>>
>>> First of all, thanks for responding to my comments and suggesting an
>>> interesting benchmark.
>>>
>>> SNAC cannot currently handle Drucker-Prager plasticity, so I'll use
>>> Mohr-Coulomb model.
>>>
>>> A more fundamental issue is that SNAC is hardwired to be 3D, which means
>>> it can solve a 2D problem using a thin 3D model with plane strain
>>> conditions.
>>> A pseudo-2D model like this will obviously raise the numerical cost
>>> compared to a true 2D one, rendering the benchmark unfair.
>>>
>>> So, could you please set up a one-element thick 3D model from your 2D model?
>>> Let me know if it's too much work on your side.
>>>
>>> I also need to know how long in terms of model time you ran this model,
>>> if it was run on a single processor, and how many time steps were taken.
>>>
>>> Finally, here is a non-technical (I guess) question.
>>> According to the Gale's manual, the Frank Kamenetskii viscosity is
>>> defined as temperature-dependent only.
>>> Then, why do we see the viscosity field varying consistently with the
>>> strain rate field?
>>> Such a correspondence is expected when viscosity is also stress-dependent.
>>> Am I misunderstanding something?
>>>
>>>
>>> Best,
>>> Eunseo
>>>
>>>
>>>
>>> Garrett Ito wrote:
>>>
>>>
>>>> Hi Eunseo,
>>>>
>>>> Aha! my little comment did catch your eye--good. Your suggestion of
>>>> comparing Gale and SNAC is a great one and I'd like to try. Here's
>>>> one we could look at. Its a simple case rifting in which extension is
>>>> driven by the two side boundaries apart, each at ~12.6 km/Myr (so full
>>>> spreading rate is 25.2 km/Myr). Free inflow at the base and top free
>>>> to move up and down. Frank Kamenetskii temperature-dependent
>>>> viscosity with Drucker Prager yielding. The temperature structure has
>>>> T=273K at the surface and 1473K at the base with a linear profile in
>>>> between. A box of postfailure strain is imposed at t=0 to control
>>>> where the faults initiate. The attached pdf shows Gale's solution in
>>>> 2D with 150x45 elements. I also attached Gale's input file so you can
>>>> see the rheology parameters. How does this sound?
>>>>
>>>> Garrett
>>>>
>>>> ----- Original Message -----
>>>> From: Eunseo Choi <echoi at ldeo.columbia.edu>
>>>> Date: Wednesday, April 29, 2009 5:34 pm
>>>> Subject: Re: [CIG-LONG] cig-long email list
>>>> To: cig-long at geodynamics.org
>>>>
>>>>
>>>>
>>>>> Hi, Garrett
>>>>>
>>>>> SNAC is a 3D code like Gale so it is supposed to be
>>>>> computationally
>>>>> expensive compared to any 2D codes.
>>>>> I believe this is not what you meant.
>>>>>
>>>>> As far as I know, the performance of SNAC and Gale has never
>>>>> been
>>>>> compared quantitatively yet. Please let me know if it's done
>>>>> even
>>>>> qualitatively.
>>>>> So, I wonder why you have the impression that SNAC is too
>>>>> expensive for
>>>>> 3D models.
>>>>>
>>>>> By the way, SNAC can do Mohr-Coulomb plasticity in 3D and
>>>>> doesn't have
>>>>> the restriction that plastic flow should always be incompressible.
>>>>>
>>>>> Eunseo
>>>>>
>>>>>
>>>>> Garrett Ito wrote:
>>>>>
>>>>>
>>>>>> Hi Mark,
>>>>>>
>>>>>> Good-- I'm glad to see 3D is starting to get a
>>>>>>
>>>>>>
>>>>> footing in the
>>>>>
>>>>>
>>>>>> community. This is my main reason for using Gale as I
>>>>>>
>>>>>>
>>>>> already do
>>>>>
>>>>>
>>>>>> faulting in 2D with FLAC (and it is my understanding that SNAC
>>>>>>
>>>>>>
>>>>> is too
>>>>>
>>>>>
>>>>>> computationally expensive in 3D ?). Correction... Mohr-
>>>>>>
>>>>>>
>>>>> Coulomb has
>>>>>
>>>>>
>>>>>> been removed from Gale because it was unstable in 3D and is
>>>>>>
>>>>>>
>>>>> identical
>>>>>
>>>>>
>>>>>> to Drucker-Prager in 2D.
>>>>>>
>>>>>> Garrett
>>>>>>
>>>>>> ----- Original Message -----
>>>>>> From: Mark Fleharty <mark.fleharty at gmail.com>
>>>>>> Date: Wednesday, April 29, 2009 12:46 pm
>>>>>> Subject: Re: [CIG-LONG] cig-long email list
>>>>>> To: Garrett Ito <gito at hawaii.edu>
>>>>>> Cc: cig-long at geodynamics.org
>>>>>>
>>>>>>
>>>>>>
>>>>>>> Garrett,
>>>>>>>
>>>>>>> It is good to hear from someone else who is doing 3D
>>>>>>>
>>>>>>>
>>>>> simulations in
>>>>>
>>>>>
>>>>>>> Gale. I am also doing 3D simulations with Gale.
>>>>>>> Welcome aboard.
>>>>>>>
>>>>>>> I thought that Mohr-Coulomb doesn't work in Gale in 3D.
>>>>>>> Was that
>>>>>>> something that got fixed?
>>>>>>>
>>>>>>> Mark
>>>>>>>
>>>>>>> On Wed, Apr 29, 2009 at 4:27 PM, Garrett Ito
>>>>>>> <gito at hawaii.edu> wrote:
>>>>>>>
>>>>>>>
>>>>>>>> Dear colleagues,
>>>>>>>>
>>>>>>>> I would like to introduce myself as a new to
>>>>>>>>
>>>>>>>>
>>>>> the cig-long
>>>>>
>>>>>
>>>>>>> list and new
>>>>>>>
>>>>>>>
>>>>>>>> GALE user. I would like to encourage us all to use
>>>>>>>>
>>>>>>>>
>>>>> the cig-
>>>>>
>>>>>
>>>>>>> long list more
>>>>>>>
>>>>>>>
>>>>>>>> often to help spread the knowledge of the CIG codes.
>>>>>>>>
>>>>>>>>
>>>>> I think
>>>>>
>>>>>
>>>>>>> it would be
>>>>>>>
>>>>>>>
>>>>>>>> helpful, for example, we made it a practice of sending
>>>>>>>>
>>>>>>>>
>>>>>>> individual questions
>>>>>>>
>>>>>>>
>>>>>>>> to cig-long along with questions you send to Walter/Eun-seo
>>>>>>>>
>>>>>>>>
>>>>>>> about the
>>>>>>>
>>>>>>>
>>>>>>>> various coding issues.
>>>>>>>>
>>>>>>>> Just to start a conversation...I have started using GALE--
>>>>>>>>
>>>>>>>>
>>>>>>> really in
>>>>>>>
>>>>>>>
>>>>>>>> collaboration with Walter Landry--over the last half year with
>>>>>>>>
>>>>>>>>
>>>>>>> interests in
>>>>>>>
>>>>>>>
>>>>>>>> applications of studying faulting and magmatism at mid-ocean
>>>>>>>>
>>>>>>>>
>>>>>>> ridges in 3D.
>>>>>>>
>>>>>>>
>>>>>>>> A lot of my work to date has been to experimenting with the
>>>>>>>>
>>>>>>>>
>>>>>>> Mohr-Coulomb,
>>>>>>>
>>>>>>>
>>>>>>>> Drucker-Prager, and StrainWeakening (e.g., damage laws and
>>>>>>>>
>>>>>>>>
>>>>>>> healing) and
>>>>>>>
>>>>>>>
>>>>>>>> understanding the faulting behavior predicted by Gale.
>>>>>>>>
>>>>>>>>
>>>>>>> Recently, we have
>>>>>>>
>>>>>>>
>>>>>>>> started running jobs in 3D, which I have found to be
>>>>>>>>
>>>>>>>>
>>>>>>> surprisingly cpu
>>>>>>>
>>>>>>>
>>>>>>>> intensive. I view improving the performance of Gale
>>>>>>>>
>>>>>>>>
>>>>> for 3D faulting
>>>>>
>>>>>
>>>>>>>> problems as an important goal and on which I will be working
>>>>>>>>
>>>>>>>>
>>>>>>> closely with
>>>>>>>
>>>>>>>
>>>>>>>> Walter and the Underworld group over the next year.
>>>>>>>>
>>>>>>>> I look forward to hearing more from you.
>>>>>>>>
>>>>>>>> Garrett
>>>>>>>> --
>>>>>>>>
>>>>>>>> =====================================
>>>>>>>>
>>>>>>>> Prof. Garrett Ito
>>>>>>>>
>>>>>>>> SOEST, Geology & Geophysics
>>>>>>>>
>>>>>>>> 1680 East-West Rd., POST 810
>>>>>>>>
>>>>>>>> Univ. of Hawaii
>>>>>>>>
>>>>>>>> Honolulu, HI 96822 USA
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> 808-956-9717
>>>>>>>>
>>>>>>>> gito at hawaii.edu
>>>>>>>>
>>>>>>>> www.soest.hawaii.edu/GG/FACULTY/ITO
>>>>>>>>
>>>>>>>> ======================================
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> CIG-LONG mailing list
>>>>>>>> CIG-LONG at geodynamics.org
>>>>>>>> http://geodynamics.org/cgi-bin/mailman/listinfo/cig-long
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>> --
>>>>>>> Mark Fleharty
>>>>>>> +1 505 217-2089
>>>>>>>
>>>>>>>
>>>>>> ---------------------------------------------------------------
>>>>>>
>>>>>>
>>>>> ---------
>>>>>
>>>>>
>>>>>> _______________________________________________
>>>>>> CIG-LONG mailing list
>>>>>> CIG-LONG at geodynamics.org
>>>>>> http://geodynamics.org/cgi-bin/mailman/listinfo/cig-long
>>>>>>
>>>>>>
>>>>>>
>>>>> --
>>>>> =====================================
>>>>> Eunseo Choi
>>>>> Post-Doctoral Research Scientist
>>>>>
>>>>> Lamont-Doherty Earth Observatory
>>>>> 303f Oceanography
>>>>> P.O. Box 1000
>>>>> 61 Rt. 9W
>>>>> Palisades, NY 10964-8000
>>>>>
>>>>> http://www.ldeo.columbia.edu/~echoi
>>>>> Phone: 845-365-8813 Fax: 845-365-8156
>>>>> =====================================
>>>>>
>>>>> _______________________________________________
>>>>> CIG-LONG mailing list
>>>>> CIG-LONG at geodynamics.org
>>>>> http://geodynamics.org/cgi-bin/mailman/listinfo/cig-long
>>>>>
>>>>>
>>>
>>>
>> --
>>
>> =====================================
>>
>> Prof. Garrett Ito
>>
>> SOEST, Geology & Geophysics
>>
>> 1680 East-West Rd., POST 810
>>
>> Univ. of Hawaii
>>
>> Honolulu, HI 96822 USA
>>
>>
>>
>> 808-956-9717
>>
>> gito at hawaii.edu
>>
>> www.soest.hawaii.edu/GG/FACULTY/ITO
>>
>> ======================================
>>
>>
>
>
>
--
=====================================
Eunseo Choi
Post-Doctoral Research Scientist
Lamont-Doherty Earth Observatory
303f Oceanography
P.O. Box 1000
61 Rt. 9W
Palisades, NY 10964-8000
http://www.ldeo.columbia.edu/~echoi
Phone: 845-365-8813 Fax: 845-365-8156
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