“…Therefore, over the years, considerable work has been reported on formulating reliable and accurate predictive schemes for estimating the drag force on a particle and/ or the free falling velocity of particles in fluids. In spite of the fact that very few applications entail the use of perfectly spherical particles, the bulk of the available literature on this topic relates to spherical particles in both Newtonian and non-Newtonian liquids (Chhabra, 1993;Ceylan et al, 1999;Wilson et al, 2003;Renaud et al, 2004;Kelessidis, 2004, for instance). This is in part 0301-7516/$ -see front matter D 2005 Elsevier B.V. All rights reserved.…”