[CIG-LONG] cig-long email list
Eunseo Choi
echoi at ldeo.columbia.edu
Fri May 1 05:39:51 PDT 2009
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
=====================================
More information about the CIG-LONG
mailing list