Particle-resolved simulations of ice slurry flows in a square duct by the thermal immersed Boltzmann method

We perform particle-resolved simulations of ice slurry flows in a square duct by using the thermal immersed boundary-lattice Boltzmann method. We investigate the effects of Reynolds number, ice packing factor, and density ratio of the ice particle to the carrier fluid on the cooling performance of ice slurry flows. In addition, we compare two collision models, i.e., a repulsion model and an adhesion model, to investigate the effect of the solid-solid interaction. As a result, we find that the Nusselt number on the duct walls increases as the Reynolds number increases, since the flow speed relative to the thermal-diffusion speed increases with the Reynolds number. Also, the Nusselt number increases as the ice packing factor increases, since the particle distribution is more dispersed due to the increase in the number of ice particles and the collision frequency. When the density of the ice particle is slightly smaller than that of the carrier fluid, the particle distribution is biased towards the top wall due to the buoyancy force (heterogeneous flow), and the net Nusselt number slightly increases compared with the homogeneous flow. Finally, we find that the adhesion model gives a much smaller value of the Nusselt number on the duct walls than the repulsion model, since particle clusters are formed by adhesion and the particles are more concentrated around the center line of the duct.