NUMERICAL INVESTIGATION OF FLOW DYNAMICS AND PARTICLE DISTRIBUTION IN A DIFFERENTIALLY HEATED CAVITY USING A TWO-PHASE EULERIAN-EULERIAN MODEL

This study is focused on understanding particle motion and its distribution inside a differentially heated cavity under free convection. The outcomes provide key insights into particle behavior in enclosed spaces, essential for contamination control in clean rooms of industries. The Eulerian- Eulerian model is employed to analyze the particle behavior inside a square cavity with silicon dioxide (SiO<sub>2</sub>) particles dispersed in the air for wide ranges of particle diameters (<i>d<sub>p</sub></i> = 0.5-40 μm), volume fractions (φ<sub>s</sub> = 0.5-5%), and Grashof numbers (Gr = 10<sup>3</sup>-10<sup>6</sup>). Finite difference techniques are employed to discretize the conservative equations of each phase, implementing sixth-order accuracy compact schemes for nonlinear terms. This model considers inter-phase coupling forces such as drag, virtual mass, thermophoresis, and Brownian forces, along with the heat interaction between the phases. Among these drag force is found to be dominant force governing the particle dynamics with its effect increasing with increasing particle size. By validating the solver with existing numerical data, our study showed that by increasing Gr from 10<sup>3</sup> to 10<sup>6</sup>, the particle volume fraction along all the walls increases, except along the bottom wall, where it decreases as the strength of convection currents intensifies and lifts the particles away from the bottom wall. Also, by increasing particle size, the particle volume fraction along the bottom wall increases, whereas on the remaining walls, it decreases. As the initial volume fraction increases from φ<sub>s</sub> = 0.5% to φ<sub>s</sub> = 5%, the increased drag force and interactions between the particles tend to dampen the particle flow velocity. Finally, the average Nusselt number is calculated to report the heat transfer study.