Numerical study on the momentum and heat transfer of porous spheroids under laminar flow

Abstract

This study focuses on the combined effect of particle shape and porosity on the momentum and heat transfer of granular matter under laminar flow. Particle-resolved direct numerical simulations (PR-DNS) are carried out at different working conditions. Numerical results show that both the particle shape (via the aspect ratio, Ar, of the spheroid) and porosity play important roles in affecting the drag coefficient (Cd) and average Nusselt number (Nu). The influence of particle shape on Cd and Nu is regardless of the particle porosity. It is found that the Cd decreases with the increase of Ar for a given Reynolds number (Re). The Nu decreases with the increase of Ar under high Reynolds number (100<Re<200), but increases first and then decreases under low Reynolds number (20<Re<100). The influence of particle porosity also highly depends on Re.Under high Reynolds number (100<Re<200), the strong influence of particle porosity on Cd and Nu is mainly caused by the increase of convectional capability of the fluid with Re which can flow into the pore structure easier. On the contrary, the effect of the particle porosity can be almost ignored under low Reynolds number (20<Re<100). Finally, superior to previously available correlations of Cd and Nu for non-spherical solid particles in fluids, the effect of the porosity is considered and novel correlations are established. The high predictive accuracy strongly demonstrates their capability.