Phase transitions in highly concentrated particle-liquid thin films

Particle-laden flows are prevalent in various industrial contexts. We experimentally investigate novel phenomena related to slurries flowing down a ramp, where the particles at the slurry front undergo a transition from a fluid-like to a solid-like state, thereby separating from the remainder of the fluid. To investigate the front dynamics and phase transitions, we simulate thin-film lubrication equations derived from the Navier-Stokes equations and particle-mass conservation. Our findings provide valuable insights into the phase transition process, revealing a quantitative dependence of front speed and fluid layer thickness on parameters such as the inclination angle, particle size, particle volume fraction, densities, and viscosity.