On the evaluation of heat and mass transfer effects on the migration behavior of neutrally buoyant particles in a Couette flow

Abstract

The effects of thermal and concentration buoyancy forces on the migration of a cold particle and multi-cold particles in a Couette flow were investigated in this paper using the combination of the Thermal-Concentration Smoothed Profile-Lattice Boltzmann Method (TCSPM-LBM). The two-dimensional Lattice Boltzmann Method was also applied for the computations related to fluid velocity, temperature, and concentration. In addition, Smoothed Profile, Thermal Smoothed Profile, and Concentration Smoothed Profile Methods were applied to calculate the hydrodynamic force, temperature exchange, and concentration exchange between the fluid and the particle, respectively. The effect of the coupling between the thermal and concentration convection on the migration path of the neutrally buoyant particle was shown by five mechanisms; these included a repulsion force due to the effect of lubrication, a Saffman lift due to the shear slip, a Magnus lift due to the particle rotation, a thermal convection, and the concentration convection. Initially, the proposed combined method was validated by comparing the obtained numerical results with the ones found in the literature, showing a good agreement. Then the effects of the forced convection, natural convection, the dimensionless numbers, the particle Reynolds number (Rep), the thermal Grashof number (GrT), the concentration Grashof number (Grc), and the Richardson number (Ri) on the equilibrium position of the neutrally buoyant particle were evaluated. Overall, the results indicated that with the increase of the Richardson number, the forced flow became weaker, leading to the increasing effect of the natural convection.