Dissolution-driven transport in a rotating horizontal cylinder (2504.05771v1)

Abstract: Dissolution, in particular, coupled with convection, can be of great relevance in the fields of pharmaceuticals, food science, chemical engineering, and environmental science, having applications in drug release into the bloodstream, ingredient dissolution in liquids, metal extraction from ores, and pollutant dispersion in water. We study the combined effects of natural convection and rotation on the dissolution of a solute in a solvent-filled circular cylinder. The density of the fluid increases with the increasing concentration of the dissolved solute, and we model this using the Oberbeck-Boussinesq approximation. The underlying moving-boundary problem has been modelled by combining Navier-Stokes equations with the advection-diffusion equation and a Stefan condition for the evolving solute-fluid interface. We use highly resolved numerical simulations to investigate the flow regimes, dissolution rates, and mixing of the dissolved solute for $Sc = 1$, $Ra = [10^5, 10^8]$ and $\Omega = [0, 2.5]$. In the absence of rotation and buoyancy, the distance of the interface from its initial position follows a square root relationship with time ($r_d \propto \sqrt{t}$), which ceases to exist at a later time due to the finite-size effect of the liquid domain. We then explore the rotation parameter, considering a range of rotation frequency -- from smaller to larger, relative to the inverse of the buoyancy-induced timescale -- and Rayleigh number. We show that the area of the dissolved solute varies nonlinearly with time depending on $Ra$ and $\Omega$. The symmetry breaking of the interface is best described in terms of $Ra/\Omega^2$.