Shocks, Solitons and Turbulence Unit (Emile Touber)

The Shock, Solitons and Turbulence (S2T) Unit carries theoretical and computational studies of energy transfers and transport arising from shock/solitary waves and turbulence. We work on a variety of problems (from cosmic to biological scales) expressed in terms of (i) fields obeying some form of conservation laws, (ii) closed using physics-based or simple behavioral arguments, (iii) and found in a turbulent and/or shocked regime. Our current activities are articulated around three main themes:

  1. Complex fluids: where the constituents of matter are “slave” particles strictly obeying physical laws. In particular, we are interested in fluids featuring a thermodynamic pressure that is locally concave (in pressure-volume space), such as near a phase transition (e.g. non-ideal fluids), electrically conductive (e.g. plasma, picture above) or out of thermodynamic equilibrium (e.g. bulk viscosity). Applications are space exploration, propulsion and power, geophysical and astrophysical flows.
  2. Active fluids: where the constituents of matter are mobile particles subjected to external forces/constraints (e.g. speed controller on a self-driven car, a penguin on the ice sheet), giving rise to an extended notion of thermodynamic pressure. Applications are traffic flows, crowd turbulence (people, animals), swarming robots.
  3. Analogous fluids: where the dynamical properties of the field can be mapped to fluid-like equations (e.g. Bose-Einstein condensates mapped to Euler flows). In particular we study systems driven by reaction-diffusion processes that trigger wave-like motions (e.g. dissipative solitons), as can be found in symbiotic plant-fungi systems, so as to develop new land-management techniques (e.g. soil decontamination, multi-species farming); or in coral reefs (to understand their evolution over long periods of time).