The effect of particle inertia on particle-induced Rayleigh Taylor instabilities

We present Direct Numerical Simulations to investigate the role particle inertia has on Rayleigh-Taylor instabilities on particle-laden flows. We consider dilute systems in which small, inertial particles are coupled to the fluid through drag. We use the two-fluid model, in which we solve for the fluid and particle motion separately. In our simulations, for a given overall density profile, we found that there are three possible outcomes: (1) For very small particles where inertia is negligible, the particle field becomes fully mixed and the instability shuts itself off. (2) For intermediate-sized particles where inertia is significant, turbulent-induced concentration can drive and maintain convection perpetually. (3) For very large particles, the rapid settling velocity prevents the development of the instability. We explore these three dynamical regimes and discuss potential applications.