Mesoscale simulation of the sedimentation of melting elliptical particle

Abstract

In this paper, a mathematical relationship between particle melting rate and its surface heat flux is established to solve the problem of melting of elliptical particle sedimentation based on the direct numerical simulations of particle sedimentation when taking account of thermal convection within the framework of the arbitrary Lagrangian-Eulerian technique. The elliptical particle with different initial angles is released in a mesoscale channel under gravity. Compared with the isothermal elliptical particle sedimentation, the melting elliptical particle shows large differences in moving trajectories, the forces exerting on the particle and velocities, which come from the consideration of fluid convection, mass loss, and shape change. More specifically, 1) in the case of isothermal elliptical particle sedimentation, the velocity, the horizontal trajectory, and the force vary periodically. However, the amplitude recedes gradually, and finally becomes zero in the case of the melting elliptical particle, which is caused by the mass lost and shape change. 2) The equilibrium position of the major axis will finally be perpendicular to the direction of sedimentation. So, the initial angle of slope (θ) usually affects the sedimentation in the beginning, and vanishes after a period of time. 3) The downward convection induced by the cold fluid accelerates the velocity of the melting particle. The angular velocity, force and horizontal amplitude of the melting particle become smaller than those of the isothermal particle, and finally recedes to zero. In our study, the investigation of coupled heat transfer, fluid-solid system and shape change is carried out, and some new features are found out.