Numerical investigation on particle inertial migration in circular Poiseuille flow with thermal convection

In this work, a numerical study on the inertial migration of particle suspension in a circular pipe with thermal effect is performed by means of the lattice Boltzmann method and the discrete element method. Both constant temperature and varied temperature conditions are taken into consideration. The migration behavior and the heat transfer are well characterized in terms of the circumferential and radial positions as well as the Nusselt number. The results show that particles tend to migrate toward the pipe bottom due to the thermal buoyancy when the fluid's temperature is higher than the particle's. For a single particle with constant temperature, it is shown that the variation of circumferential equilibrium position can be well regressed by the Richardson number and divided into three zones, i.e., an inertial lift dominating zone, a transition zone, and a buoyancy dominating zone. Both the radial equilibrium position and the Nusselt number are sensitive to the Reynolds number and increase consistently with the Grashof number. For particle suspension with constant temperature, similar migration behavior is observed with an enlarged transition zone. However, a nonmonotonic variation of the radial equilibrium position as well as the Nusselt number is discovered, which is attributed to the particle crowding effect. For varied temperature conditions, the migration process is affected by the heat capacity ratio and the Prandtl number, which determine the heating rate of the particle. Nevertheless, the radial equilibrium position is irrelevant with the thermal effect, which only depends on the Reynolds number and resembles the isothermal condition.