Dr. Joris Picot

Contact information

Joris PICOT
Laboratoire de l'Informatique du Parallélisme
ÉNS Lyon — site Jacques Monod
46, allée d'Italie
69 007 LYON
France
+33 (0) 4 72 72 86 48
jpicot@enscbp.fr
https://perso.ens-lyon.fr/joris.picot/

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Curiculum Vitæ

Current position

Research engineer at LIP, since October 2017.

Scientific skills

Physics:     Fluid dynamics,    Turbulence,    Atmosphere,    Ice microphysics.

Numerics:    Finite differences method,    Finite volumes methods,    Velocity-pressure coupling,    Lagrangian particle models,    Immersed boundaries,    Large-eddy simulations,    Linear system solving,    High-performance computing.

Computing skills

Computing languages:    Fortran (77—2008),    Python (2—3, numpy, scipy, flask),    C/C++,    Julialang,    bash,    MPI,    OpenMP.

CFD software:    Notus,    NTMIX,    Méso-NH,    gmesh.

Visualisation software:    VisIt,    Tecplot,    Paraview,    Gnuplot,    Metapost,    Asymptote,    Gimp,    Inkscape

Internet:    HTML/CSS,    Javascript,    Flask,    Nginx,    Baikal.

Office:    LaTeX,    Beamer,    Tikz,   Word,    Excel,    Power Point,    Publisher,    Libre Office,    Scribus.

Environments:    Linux,    Archlinux,    Git,    Cmake.

Past Experience

‣ 2017 January—October: Post-doctoral fellow

Development of phase field methods for the melting of salts in porous media.

Location: I2M, Bordeaux, France.

Keywords: Phase change, Phase field.

Projects: ANR Phasefiels

‣ 2014—2016: Research Engineer

Developer of the Notus project. In charge of the immersed boundary aspects.

Location: I2M, Bordeaux, France.

Keywords: Notus, Immersed boundaries.

Projects: IdEx CPU

‣ 2012—2014: Post-doctoral fellow

Development of a binned microphysical model of ice particles in the mesoscale model of Météo France (Méso-NH).

Location: CERFACS, Toulouse, France.

Keywords: Ice microphysics, Meso-NH, Airborne measurments.

Projects: TC2

‣ 2009—2012: Ph. D.

Effects of atmospheric turbulence on the microphysical properties of young condensation trails.

Location: CERFACS, Toulouse, France.

Keywords: Atmospheric turbulence, Stratified Atmosphere, Ice microphysics, Compressible fluid dynamics, Large-eddy simulations, Lagrangian particle models, Numerical generation of anisotropic turbulence, High-performance computing, NTMIX,

Projects: ITAAC.

Thesis defence: February 28, 2012

Publications

  • J. Picot and S. Glockner: “Reduction of the discretization stencil of direct forcing immersed boundary methods on rectangular cells: The ghost node shifting method,” Journal of Computational Physics 364, 18-48, 2018; doi: 10.1016/j.jcp.2018.02.047.
  • J. Picot, R. Paoli, O. Thouron, and D. Cariolle: “Large-eddy simulation of contrail evolution in the vortex phase and its interaction with atmospheric turbulence,” Atmospheric Chemistry and Physics 15, 7369-7389, 2015; doi: 10.5194/acp-15-7369-2015.
  • R. Paoli, O. Thouron, J. Escobar, J. Picot, and D. Cariolle: “High-resolution large-eddy simulations of sub-kilometer-scale turbulence in the upper troposphere lower stratosphere,” Atmospheric Chemistry and Physics 14, 5037-5055, 2014; doi: 10.5194/acp-14-5037-2014 .
  • R. Paoli, L. Nybelen, J. Picot, and D. Cariolle: "Effects of jet/vortex interaction on contrail formation in supersaturated conditions," Physics of Fluids 25, 053305, 2013; doi: 10.1063/1.4807063 .
  • J. Picot: Simulation aux grandes échelles de traînées de condensation dans un milieu atmosphérique stratifié et turbulent (Ph. D., 2012); Université de Toulouse, 2013; tel-00828483 .
  • J. Picot, R. Paoli, O. Thouron, and D. Cariolle: “Effects of atmospheric turbulence and humidity on the structure of a contrail in the vortex phase,” 3rd International Conference on Transport, Atmosphere and Climate; Prien am Chiemsee, Germany, 2012; proceedings .

Teaching

Year Subject Level Volume
2014/2015 Mathematics BAC+1 32 h
2015/2016 Mathematics BAC+1 52 h
Total 84 h

 


Gallery — thesis

The first part of the thesis was dedicated to the numerical generation of sustained atmospheric turbulence. On the picture below, one can see the thin horizontal layers of fluctuations imposed by stratification of the atmosphere. The more turbulence there is, the more small structures appears.

Vertical (top) and horizontal (down) sections of potential temperature difference with respect to the average vertical profile, for mild (left) and weak (right) turbulence levels. The reference vertical coordinate corresponds to an altitude of 11 km.

The second part of the thesis was dedicated to the numerical simulation of young condensation trails. The picture below show the interest to use the turbulence field above in condensation trail simulations. The vortex break-up occurs within the appropriate timescale without resorting to artificial methods (such as in the “Sans turbulence” case), and the formation of “puffs” at the bottom of the contrail is very similar to those observed in the atmosphere. The microphysical properties of the contrail (size distribution, optical thickness, etc.) are also affected.

Comparison of the spreading of ice particles with and without turbulence (“Avec turbulence” and “Sans turbulence, respectively). From left to right and top to bottom, snapshots are taken every 30 s starting from 0 s up to 2 min 30 s. Ice particles are colored with respect to their sizes.

 


Gallery — I2M

The Immersed boundary method is a technique to implement “arbitrary” boundaries in a Cartesian numerical simulation. The picture below show an example realized with Notus of a “pacman” or a “camembert“ inserted in a fluid flow.

Incompressible Navier-Stokes flow around a Pacman. Re = 60. The fluid is colored by velocity magnitude.

Such a technique is well adapted to flow field simulation is the Lascaux caves. As show below, the very complex and intricate boundary of the cave makes it very difficult to generate body-fitted grids.

Surface grid of the Lascaux caves. Resolution ~ 5 cm.

The large and complex geometry of the Lascaux caves makes these simulation very challenging. Pictures below show a preliminary simulation of convection in the Lascaux caves, using 1st-order accurate methods.

Horizontal cross-sections of the vertical velocity field (left) and temperature field (right).

 


Gallery — I2M #2

The heating of complex systems

Phases (left) and temperature (right) of the heating of a salt capsule in a graphite matrix.