Effects of the gravitational force on the convection turbulence driven by heat-releasing point particles

Abstract

In this work, we study the convection turbulence driven by heat-releasing point particles, which absorb energy for external sources. Two-way coupling is considered for both momentum and temperature fields, and the particle dynamics includes both the Stokes drag, which is measured by the Stokes number, and the gravity force, which is measured by the Froude number. The gravity effect of particles on the convection turbulence is mainly researched. Two regimes are identified at large and small Froude numbers, respectively. For a large Froude number, the flow can reach a statistically steady state with particles being constantly advected over the whole domain. Within this regime, the transport properties exhibit weak dependence on the Froude number but strong dependence on the Stokes number. When the Froude number is small enough, all particles eventually accumulate toward the boundary layer region near the bottom plate. Scaling laws are derived for the critical Froude number between the two regimes, which agree well with the numerical results.