Radiation-induced turbulence in particle-laden buoyant flows

Particle laden flows are of tremendous importance in oceanography, geophysics, meteorology, astrophysics, and process technology. In the presence of thermal radiation, non-uniformities in particle concentration result in local temperature fluctuations (spatial and temporal), due to the different absorptivity between dispersed and carrier phases. Under the influence of gravity or other acceleration fields, fluid motion is induced by buoyancy, altering the particle distribution and possibly inducing higher non-uniformities. Numerical simulations have been performed which illustrate this effect. It is shown that for a broad range of parameters a (e.g. radiation intensity, acceleration, density ratio and number density) feedback loop between the local particle concentration, the temperature fluctuations and the buoyancy forcing can create and sustain turbulence. Inertial particles are observed to cluster and create high temperature plumes. When the particle response time is comparable to the characteristic lifetime of the plumes, the system exhibits intense fluctuations of turbulent kinetic energy and maximum concentration.