Drag coefficient and averaged Nusselt number of a scalene prolate ellipsoid

Abstract

• Momentum and heat transfer characteristics of a scalene prolate ellipsoid were studied. • Effects of particle shape, orientation and Reynolds number were discussed. • Existing correlations for the drag coefficient and averaged Nu were improved. A cold fluid flowing past a hot stationary scalene prolate ellipsoid is numerically studied via a three-dimensional immersed boundary-lattice Boltzmann model (IB-LBM). First, axisymmetric ellipsoids are considered for verification purposes, and good agreement is found between obtained drag coefficient ( C d ) and averaged Nusselt number ( Nu ) and previously reported results. Subsequently, 81 case studies are conducted by changing shape (2 ≤ Ar 1, Ar 2 ≤ 6) and incident angle (0° ≤ θ ≤ 90°) of the ellipsoid as well as the Reynolds number (25 ≤ Re ≤ 200). In this study, we particularly consider scalene prolate ellipsoids with unequal Ar 1 and Ar 2, which have not been studied in detail before. Effects of different factors on momentum and heat transfer characteristics between solid and fluid phases are understood based on the analysis of numerical results. Available formulas reported in the literature are also briefly reviewed. Finally, new correlations for both C d and Nu are developed using the most important factors with average deviations of 3.875% for C d and 1.598% for Nu , respectively. These proposed correlations can be used to facilitate the phase coupling in the multi-phase flow modelling.