[CIG-LONG] Dike hill problem

[Taichi SATO]

Dear Walter,

Thank you very much for your response!

However, I think the input file does not work 
well, the result is something odd.

1)Strain field spreads in the "air" layer.

2)Continuous faulting does not occur. This occurs 
whether putting the air layer or not.

For the problem 2), I think this is because the 
problem with the low viscosity around the dike 
still remains. This might be caused by the strain 
around the dike. The new materials created in the 
dike deform immediately as the materials flow out 
from the dike.
I think this lower viscosity interferes the 
continuous faulting process.

Would you give me advices to fix these problems?

Sincerely,

Taichi

(2010/06/01 15:05), Walter Landry wrote:
> Taichi SATO<taichix at aori.u-tokyo.ac.jp>  wrote:
>> Dear walter,
>>
>> Thank you very much!
>> I attached recent my input file. It may be useful for solving the
>> problem.
>
> Sorry this has taken so long.  It turns out that the way MeshShapeVC
> is used is not the best.  This is my fault, and I apologize.  In the
> past, I thought that the area that MeshShapeVC affects is constant as
> the grid distorts.  It turns out that MeshShapeVC chooses the points
> at the beginning and never changes.  So as the surface moves up and
> down, your divergence region expands and compresses.
>
> The way to solve this is to put in an 'air' layer and fix the top of the
> simulation.  Air layers often cause problems when there is subduction,
> because air can get advected underground and spuriously lubricate the
> interface between the plates.  I do not think that is an issue for
> this simulation.
>
> However, you will see some sub-grid behaviour that seems odd.  For
> example, you will see small structures that should collapse.  A small
> part of this is because the viscosity of the 'air' is not as close to
> zero as it should.  But most of it is because of the finite resolution
> of the grid.  As you increase the resolution, the size of the features
> gets smaller.
>
> Also, because the air layer has a fairly low viscosity, the time step
> needs to be relatively small.  You can try modifying the viscosity of
> the air to see how large you can make it.
>
> I am attaching a copy of the new input file.  Let me know if this
> works for you.
>
> Cheers,
> Walter Landry
> walter at geodynamics.org
>
>
>
>
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