Drag forces and heat transfer coefficients for spherical, cuboidal and ellipsoidal particles in cross flow at sub-critical Reynolds numbers

This work is devoted to the numerical calculation of heat and fluid flow past spherical particles and non-spherical particles of various shapes. Although numerous works have investigated drag forces (c(d)) for spherical and non-spherical particles, works about the Nusselt number (Nu) relations for non-spherical particles are rare. Motivated by this fact, as a first step we consider cuboid, spherical and ellipsoidal particles in steady-state regimes corresponding to Reynolds numbers (Re) from 10 up to 250. Due to the asymmetric flow existing when Re approaches the value of 250, all simulations are made using a three-dimensional domain. Good agreement was observed when our numerical results gained for the sphere were compared with published values for drag coefficients and Nusselt numbers. Based on the analysis of numerical results obtained for non-spherical particles we found out that in addition to the Reynolds number three geometry parameters influence particle-fluid interaction: the drag coefficient depends primarily on the normalized longitudinal length, while both the sphericity and the crosswise sphericity influence the Nusselt number. For that reason new correlations are developed for both the drag coefficient and the Nusselt number. The accuracy of the closures developed for c(d) and Nu is discussed in a comparison with published models. (c) 2011 Elsevier Ltd. All rights reserved.