Julien Diaz

Responsabilities

• Head of Team Mescal of the LMAP (2019-)
• Member of Bureau du Comité des projets de l'Inria Bordeaux Sud Ouest (2020-)
• Member of the Inria Scientific Board (2014-2019 )
• Member of the Comité Technique Inria (2014- )
• Member of the Inria Administrative Board (2014- )
• Member of the Inria Evaluation Committee (2008-2014)

Research interests

Numerical and mathematical aspects related to elastodynamic and acoustic wave propagation phenomena.

High-order schemes in space and in time for the discretization of the wave equation

Key words:
High order finite elements, Discontinuous Galerkin Method, Non conforming meshes, Local time stepping.

Artificial Boundary Conditions in acoustic and aeroacoustics

Key words:
Perfectly Matched Layers, High Order Absorbing Boundary Conditions, Error estimates, Cagniard-de Hoop method.

Analytical Solution to Wave Propagation Problem

Key words:
Cagniard-de Hoop method, Bilayered Media, Acoustic, Elastodynamic, Poroelastic.

Supervision

PhD in progress

• Vinduja Vasanthan co-advised with H. Barucq
• Stefano Frambati co-advised with H. Barucq
• Rose-Cloé Meyer co-advised with H. Barucq
• Pierre Jacquet co-advised with H. Barucq.

 PhD

• Chengyi Shen Études expérimentales et numériques de la propagation d'ondes sismiques dans les roches carbonatées
  en laboratoire, co-advised with D. Brito. Defended en June 2020.
• Elvira Shishenina Space-Time Discretization of Elasto-Acoustic Wave Equation in Polynomial Trefftz-DG Bases, co-advised with H. Barucq. Defended on December 2018
• Izar Azpiroz Contribution to the Numerical Reconstruction in Inverse Elasto-Acoustic Scattering, co-advised with H. Barucq. Defended on February 2018
• Marie Bonnasse-Gahot Simulation de la propagation d’ondes élastiques et visco-élastiques
  en régime harmonique par des méthodes Galerkin discontinues d’ordre élevé en maillage non-structuré adaptées au calcul haute performance (Simulation of elastic and viscoelastic wave propagation in harmonic domain by high-order Discontinuous Galerkin method in a High Performance Computing framework), co-advised with S. Lanteri. Defended on December 2016
• Jérôme Luquel. Imagerie de milieux complexes par équations d’ondes élastiques (Imaging of complex elastic media), co-advised with H. Barucq. Defended on April 2015
• Lionel Boillot Propagateurs optimisés pour les ondes élastiques en milieux anisotropes (Optimized propagators for elastic waves in anisotropic media), co-advised with H. Barucq. Defended on December 2014.
• Florent Ventimiglia Schémas d’ordre élevé et pas de temps local pour les ondes élastiques en milieux hétérogènes (High order schemes and local time stepping for elastic waves in heterogenous media) , co-advised with H. Barucq. Defended on June 2014.
• Cyril Agut. Schémas numériques d’ordre élevé en espace et en temps pour l’équation des ondes (High-Order Schemes in space and in time for the wave equation), co-advised with H. Barucq. Defended on December 2011.
• Véronique Duprat. Conditions aux limites absorbantes enrichies pour l’équation des ondes acoustiques et l’équation d’Helmholtz (Enriched absorbing boundary conditions for acoustics wave equation and for Helmholtz equation), co-advised with H. Barucq. Defended on December 2011.
• Caroline Baldassari. Modélisation et simulation numérique pour la migration terrestre par équation d’ondes (Modelling and numerical simulation for terrestrial migration by wave equations), co-advised with H. Barucq. Defended on December 2009.

Projects

Transfer

I develop numerical schemes for the simulation of seismic wave propagation and I supervise in the implementation of the new schemes in the platform of Total.

These developments are achieved in collaboration with PhD students funded by Total in the framework of the strategic action “<a href="https://dip.inria.fr"> Depth Imaging Partnership (DIP) </a>”. I am currently coadvising the PhD thesis of Pierre Jacquet (with H. Barucq). I was also coadvisor of the PhD theses of Marie Bonnasse-Gahot, defended in december 2015, Jérôme Luquel, defended in april 2015, Lionel Boillot defended in December 2014, Florent Ventimilgia, defended in June 2014n and Caroline Baldassari, defended in December 2009.

Software

Numerical Simulation of Waves Propagation in time-domain and in harmonic Domain.

• Hou10ni

This code has been realized in collaboration with Hélène Barucq and Élodie Estécahandy. It is based on the Interior Penalty Discontinuous Galerkin Method and computes the solution to acoustics wave propagation problem in heterogeneous media. It is able to consider both time-domain and harmonic-domain (Helmholtz). The extension to elastodynamics equation in 2D and to the coupling between elastic and acoustic has been implemented by Élodie Estecahandy

• 2D version: this version can compute the solution to acoustic, elastodynamic or elasto-acoustic equations. It allows for the use of arbitrary high-order elements and curved elements,
• 3D version : this version can compute the solution to acoustic and elastodynamic wave equation. The implementation of arbitrary high-order elements and curved elements and the extension to elasto-acoustic is a work in progress.

Analytical Solutions of Wave Propagation Problems in Stratified Media.

The two following pieces of software have been realized in collaboration with Abdelâaziz Ezziani. The parallelization of the 2D version has been realized in collaboration with Nicolas Le Goff.

• Gar6more 2D v2.0

• Gar6more 3D v2.0

Publications