Nicolas Kofman

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Post-Doctorant

nicolas.kofman@epfl.ch

Nationalité : French

EPFL STI IGM LFMI
ME A2 444 (Bâtiment ME)
Station 9
CH-1015 Lausanne

Site web: http://lfmi.epfl.ch/
Unité: LFMI

Données administratives

Compétences

- Windows, Mac OS, Linux
- Mathematica, Gnuplot, AUTO, Gerris
- Programming in Fortran, LaTeX, Matlab
- Theory of hydrodynamic instabilities
- Desiging, building test benches
- Liquid film thickness measurements
- Experience in cryogenics, microfluidics
- English (advanced), Italian (intermediate)

Publications

Recherche

    Thin liquid films flowing down an inclined plane (PhD)

    Due to the Kapitza instability, waves are formed at moderate Reynolds numbers. These waves reorganize into localized structures (solitary pulses) which notably enhance the heat and mass transfers between both phases. To optimize these latter, it is crucial to know the precise characteristics of the waves. We study their synchronization in the 2D case and their 3D modes of instability. We use both experimental tools (shadowgraphy, film thickness measurements) and numerical analysis through a reduced set of equations (Ruyer-Quil-Manneville).


    Thin liquid films sheared by a counter-current gas flow (PhD)

    This study represents a main issue for several industrial process (evaporators, coolers, distillation columns). The optimal operating conditions are close to the onset of flooding, for which a sharp increase in the pressure drop and decrease in the efficiency are observed. We study experimentally the influence of a counter-current air flow on the solitary waves. Their amplitude, speed and 3D features are found to be strongly affected. The flooding point is characterized by the emergence of waves going upstream.


    Dripping under an inclined plane (postdoc)

    When the plane is reversed, 2D stationary wave profiles computed with the Ruyer-Quil-Manneville model can be unstable and lead to the formation of droplets. We analyze their 2D/3D secondary modes of instability and compare with direct numerical simulations of the Navier-Stokes equations.


    Other research topics

  • Instability of liquid films coating the interior of cylindrical surfaces (postdoc)
  • Gravity-driven pancake droplets in a Hele-Shaw cell (postdoc)
  • Scraping of viscous fluids by an inclined plate (postdoc)
  • Flooding of sheared liquid films in cryogenic conditions (PhD)
  • Aerodynamic flutter of a flexible plate (internship)