[CIG-SHORT] Constant displacement boundary condition

[Mamun Miah]

Thanks, Brad Aagaard and Brad Hager. I am thinking to model a rigid plate
and define an interface between the rigid plate and the actual specimen in
PyLith.  I went through Jha's paper before. His workaround involves
different arrangement of BCs than the actual Mandel's. Maybe I should do
something like that in stead of getting bogged down to the original BCs.

I really appreciate your valuable input.

Thanks,
Mamun

On Tue, Oct 27, 2015 at 10:27 AM, Brad Aagaard <baagaard at usgs.gov> wrote:

> Mamum,
>
> I agree with Matt. A Dirichlet BC appears to exactly match your diagram of
> roller BC on the top and bottom.
>
> Regards,
> Brad
>
>
>
> On 10/27/2015 10:24 AM, Mamun Miah wrote:
>
>> Thanks, Matt for your quick reply. Actually, I am not explicitly
>> specifying
>> the constant displacement. A load is being applied on the top and bottom
>> of
>> the specimen and I have to make sure that specimen compresses uniformly on
>> the top and bottom sides by the action of rigid plates. Not sure it was
>> clear enough. Please look at the mandel.jpg I attached earlier.
>>
>> On Tue, Oct 27, 2015 at 10:18 AM, Matthew Knepley <knepley at mcs.anl.gov>
>> wrote:
>>
>> On Tue, Oct 27, 2015 at 12:15 PM, Mamun Miah <mmiah at go.olemiss.edu>
>>> wrote:
>>>
>>> Dear Brad et al.,
>>>>
>>>> I am trying to model Mandel's problem with TOUGH2-PyLith where I need to
>>>> make sure that there is a constant displacement boundary condition
>>>> (i.e. Uz
>>>> = const. at +- b) at the top and bottom boundaries (please see
>>>> mandel.png).
>>>> The load has to be applied on the specimen through rigid plates that
>>>> makes
>>>> sure that there is no differential displacement on the top and bottom
>>>> sides
>>>> with time.
>>>>
>>>> Right now, I am applying a 'traction-normal' on the +Z and -Z surfaces
>>>> as
>>>> Neumann BCs in the geometry attached (specimen.png). But it does not
>>>> seem
>>>> to replicate the load application through RIGID PLATES.
>>>>
>>>> Any idea or hints would be appreciated.
>>>>
>>>>
>>> If you want a guaranteed displacement, why would you use traction
>>> conditions? That seems crazy. Why not
>>> just use a Dirichlet displacement condition? That is what they are for.
>>>
>>>    Matt
>>>
>>>
>>> Mamun
>>>> --
>>>> Thanks & Best Regards,
>>>>
>>>> Mamun Miah
>>>> Graduate Research Assistant
>>>> Department of Civil Engineering
>>>> The University of Mississippi
>>>> Oxford, MS 38655
>>>> Phone: (662)-801-1904
>>>> Website: http://www.linkedin.com/pub/mamun-miah-eit/21/53/339
>>>>
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>>>>
>>>>
>>>
>>>
>>> --
>>> What most experimenters take for granted before they begin their
>>> experiments is infinitely more interesting than any results to which
>>> their
>>> experiments lead.
>>> -- Norbert Wiener
>>>
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>>>
>>
>>
>>
>>
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-- 
Thanks & Best Regards,

Mamun Miah
Graduate Research Assistant
Department of Civil Engineering
The University of Mississippi
Oxford, MS 38655
Phone: (662)-801-1904
Website: http://www.linkedin.com/pub/mamun-miah-eit/21/53/339
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