Turbulent Thermal Convection Driven by Heat-Releasing Particles

Thermal convection driven by heat-releasing particles in a quasi-3D cavity has been investigated through four-way coupled Euler-Lagrange direct numerical simulations. To examine the effects of thermal buoyancy and particle inertia, the Rayleigh-Robert number and density ratio are chosen in the range of \(4.97 \times 10^5 \le Rr \le 4.97 \times 10^8\) and \(1 \le \rho _p /\rho _f \le 250 \) , respectively, and the Prandtl number \(Pr=1\) . Compared to the convection driven by uniform internal heating, it is found that the particles of small inertia ( \( \rho _p /\rho _f =1\) ) have a weak effect on enhancing convective heat transfer as Rr increases. The ensemble-averaged temperature is highly dependent on the spatial distribution of particles. For higher inertia ( \( \rho _p /\rho _f\ge 10\) ), the particles are expelled away from the vortex core by the centrifugal force originating in the particle-vortex interaction. It results in the preferential accumulation of particles commonly at the vortex edges and, consequently, a highly non-uniform distribution of heat sources. Of interest, the occurrence of preferential accumulation may suppress or promote the heat escaping through the walls, namely, redistributing the heat flux on the top and bottom walls.