Turbulent sedimentation: a new form of Rayleigh-Taylor mixing

The sedimentation of finite-size inertial particles in a Rayleigh-Taylor-like setup is studied by state-of-the-art direct numerical simulations.

The falling particles are observed to produce two distinct regions: a leading mixing layer with a linear concentration profile followed by a bulk region of uniform density.

Unlike classical RT turbulence, the mixing layer extension accelerates with an anomalous, non-integer exponent, while the bulk region moves at a constant velocity.

A one-dimensional model based on a local hindered settling law accurately captures the observed dynamics and its dependence on the density ratio.