Effects of Mass Eccentricity on the Motion of Spherical Particles in Shear Flows

A particle-resolved simulation is performed on the motion of spherical particles with an eccentric internal mass distribution in laminar and turbulent vertical flows subjected to horizontal shear in order to examine the effects of mass eccentricity on the motion of particles in shear flows. A spherical shell/hollow particles with an inner spherical core is focused on as a typical example of mass eccentric particles. The Navier-Stokes equations and the Newton-Euler equations are solved for the fluid phase and the particles, respectively. An immersed boundary method is adopted to represent the shell particle. The Newton-Euler equations are solved using the body-fixed coordinate system and four quaternion parameters, considering the deviation of the mass center from the center of the spherical shell particle. Numerical results show that a particle tends to stop its rotation when the torque acting on the particle due to the gravity exceeds that due to the shear. It is found that the transverse migration of mass-eccentric particles becomes less vigorous in both laminar and turbulent flows since the effect of the Magnus force is also weakened for mass-eccentric particles. It is also found that the evolution of fluid kinetic energy is significantly affected by the mass-eccentricity of particles in laminar flows.