A coupled DEM-FTSM approach with a new cost-effective searching algorithm of particles for gas-solid flow with heat transfer

Abstract

The utilization of thermal energy in solid-gas flow is one of matters of general interest, and therefore the phenomena in solid-gas flow play important roles for interactions of particle-gas, particle-particle, and heat transfer. A coupled discrete element method (DEM) - fast transform spectral method (FTSM) approach is developed for non-isothermal gas-solid flow in a smooth-wall vertical channel. The motivation for this research is to use the coupled DEM-FTSM approach to study the influence of mass loading ratio on the heat transfer of gas-solid flow. The mass loading ratio is increased till 4, which is relatively higher under the background of modern direct numerical simulation (DNS) of gas-solid flow with particle diameter of 500 μm. Both the particle-gas and inter-particle interactions are taken into account. A new cost-effective searching algorithm of particles is developed to record the particle-feature point pair. A smoothed Dirac delta function is adopted to link the point particles and the gas flow field for the first time. The feature point is also used to divide the computing domain into a number of blocks for investigating the influence of inter-particle interactions. The comparative results demonstrate that the predictions of the coupled DEM-FTSM approach are in good agreement with the known results. It is shown that the difficulty of the excessive computational cost in the traditional CFD-DEM approach can be overcome by applying the present method. The final simulation results indicate that particles have a great influence on the heat transfer of the gas-solid flow. Moreover, as the mass loading ratio increases, the heat transfer capacity of the gas-solid flow also increases significantly.