Drag and heat transfer characteristics around and through two interactive porous particles

Abstract

When the concentration of porous particles reaches a certain level, the interactions between the particles can't be ignored. Therefore, this paper numerically investigated the interactions between two porous particles using the lattice Boltzmann method. In this paper, two-dimensional steady flow and heat transfer around and through two porous particles with the same diameters (D) was studied numerically. The effects of Reynolds number (Re), Darcy number (Da), center-to-center distance (expressed as dimensionless form L/D), angle between two porous particles (β) and particles with different permeability on the flow and heat transfer characteristics were investigated in detail. The investigated ranges of the parameters were 10 ≤ Re ≤ 40, 10−6 ≤ Da ≤ 10−2, D ≤ L ≤ 4D and 0° ≤ β ≤ 90°. It is observed that these parameters have significant effects on the flow and temperature fields, drag coefficient and average Nusselt number. The drag coefficient and average Nusselt number of the leading particle (P1) is much larger than those of the trailing particle (P2) in most instances. And the two porous particles show different change tendency to the same changes of these parameters. The effects of Da on P1 are more prominent compared with P2 while the effects of L/D on P2 are more obvious compared with P1. Besides, the drag coefficient of P2 increases with β increasing. In addition, we define drag force ratio and heat transfer enhancement ratio to compare the sensitivity of particles to the changes of Re and/or Da when two particles coexist and when one particle exists alone. The results indicate the heat transfer efficiency of P1 is more sensitive to changes in Da and Re compared with a single porous particle.