[CIG-SEISMO] Help needed to use deformation field as an input of SPECFEM2D

[Dimitri Komatitsch]

Hi Jérôme,

Thanks for your question. Since the equation is second order in time, 
one needs two initial conditions, usually we input the displacement 
vector and the velocity vector at time t = 0 when the medium is not 
initially at rest; another option (mathematically equivalent in the 
context of the discretized equation) is to input the displacement vector 
at two different times, say t = 0 and t = + delta_t for instance, where 
delta_t is the time step of the time scheme.

I am not familiar with how this can (or cannot) be done easily by 
inputing spatial gradients of that (for instance the strain), but the 
answer is very likely for instance in Tom Hughes' 1987 book 
https://www.amazon.com/Finite-Element-Method-Mechanical-Engineering/dp/0486411818
(around chapter 9 or so if I remember correctly).

Best wishes,
Dimitri.

On 05/24/2018 12:24 PM, AZZOLA Jerome (JDS) wrote:
> Hello,
> 
> First, I would like to thank CIG Seismology for providing Specfem2D and 
> other very useful Software with free access.
> I'm a PhD student at IPGS - University of Strasbourg and I use Specfem2D 
> to simulate the propagation of waves in a plate containing holes and 
> meshed using the external mesher GMSH. The mesh input in Specfem2D is 
> continuously deformed using Code_Aster, a finite element code treating 
> the mechanical deformation of the mesh. Usually, we define to groups of 
> elements: the bulk of the plate and the holes. We define the velocity 
> and density in each model. We would like by now to use the deformation 
> field computed from Code_Aster at each element of the mesh used in both 
> codes to define the velocity field input in Specfem2D. Do I have to use 
> as many models in my ParFile as the number of elements or is there a 
> simpler way to use the deformation field as an input of SPECFEM?
> Thank you for your help.
> 
> 
> Cordially,
> 
> 
> --
> 
> Jérôme AZZOLA
> Doctorant en géosciences
> Tél : +33 (0)7 68 54 92 57
> azzola at unistra.fr <mailto:azzola at unistra.fr>
> jerome.azzola at gmail.com <mailto:jerome.azzola at gmail.com>
> www.unistra.fr <http://www.unistra.fr>
> EOST - Ecole et Observatoire des Sciences de la Terre
> 5, rue René Descartes
> F - 67000 Strasbourg
> 
> 
> 
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-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr