Intern seminars : Jason Barckicke and Nathan Martin-Fournier

Kelvin waves along a free-surface vortex: dispersion relation and wave turbulence, Jason Barckicke

Many flows feature a strong vorticity: tornadoes, hurricanes, aircraft wakes … Vortices also play a key role in the energy cascade of classical and quantum turbulence. Kelvin waves are elementary perturbations of such vortices – helical waves propagating along the vortex line.

Many theoretical works have predicted their behaviour but no experimental confirmation has been reported so far.

By designing an original experimental set up, consisting in a bathtub vortex without rotation of the tank, we measured the Kelvin wave dispersion relation, with good resolution, for the first time. Their spectral signature is very rich and includes several wave modes. They all match the theoretical predictions.

We then turn to investigating Kelvin wave turbulence – a phenomenon carrying energy towards small scales through nonlinear wave interactions.

It paves the way to the experimental study of solitons and the dynamics of an array of vortices, whose collective motion is known as ‘Tkachenko waves’.

 

MSC platform dedicated to mecanobiology, Nathan Martin-Fournier

This seminar, made mostly for students (but which could be interesting to non-students as well), aims at giving a tour of the different experimental setups for mechanobiology available at MSC and its vicinity. These setups either allow the application of controlled mechanical contraints on biological samples, or the measurements of force, rigidity or viscosity at a microscopical scale. Maybe these systems will be useful to you in your research work?