Analysis of the turbulent forcing in particle-laden flow induced by radiation

The proposed study focus on the interplay of hydrodynamic turbulence, radiative heating and particle transport. These three fundamental phenomena are encountered simultaneously in many branches of physical science, from meteorology to engineering, oceanography and astrophysics. The flow under interest is a novel phenomenon that is responsible for the high local concentration of inertial particles in presence of thermal radiation. Specifically, we consider a large number of particles, immersed in a transparent fluid, and subject to thermal radiation. Initial nonuniformities in particle concentration result in local temperature fluctuations, due to the different absorptivity of the dispersed and carrier phases. Under the influence of gravity or other acceleration fields, fluid motion is induced by gas expansion and buoyancy, altering the particle distribution and inducing higher non-uniformities. With respect to other dispersed multiphase flow problems, the main difference is the retroaction of the dispersed phase on the carrier fluid, which happens here through the thermal energy released in the fluid by conduction and convection. The equations of motion are simplified according to the Oberbeck-Boussinesq approximation, whereas in the particle equation of motion only the Stokes drag and the gravitational force are retained. Those equations are solved by DNS using a pseudo-spectral method, and the evolution of the particle velocities and positions is obtained by Lagrangian tracking. The objective of this paper is to investigate the consequence of the peculiar "two-way coupling" forcing and its consequences on the resulting turbulence.