Abstract

We present a physical and computational analysis of the flocculation of suspended cohesive particles in turbulence by one-way coupling. Our numerical method can separately consider the cohesion, lubrication, and direct contact forces for each pair of particles, thereby allowing us to conduct a detailed analysis of their influence on the flocculation process in turbulence. We first test the numerical approach in the two-dimensional cellular flow which consists of Taylor-Green vortices and investigate the binary interaction of cohesive particles. Further, we numerically investigate the flocculation of suspended cohesive particles with significant surface roughness in homogeneous isotropic turbulence and analyze the temporal evolution of the average sizes. Stronger cohesion and weaker turbulent shear yield larger flocs. The increase of the Stokes number limits the growth of flocs. The influence of the particles' roughness on flocculation is compared. Larger roughness yields a smaller equilibrium floc size while it does not affect the flocculation rate.