Drag on non-spherical particles: an evaluation of available methods

In this work, a selection of widely used correlations have been critically evaluated for estimating the drag coefficient of non-spherical particles in incompressible viscous fluids. Experimental results have been culled from 19 independent studies embracing wide ranging particle shapes including cylinders, needles, cones, prisms, discs, rectangular, parallelepiped and cubes. The resulting data base consisting of 1900 data points encompasses wide ranges of physical and kinematics conditions as: sphericity, 0.09 to 1 and the Reynolds number ranging from 10-4 to 5×105. In particular, the performance of five methods has been critically examined. The best method appears to be that of Ganser which uses the equal volume sphere diameter and the sphericity of particle. The resulting overall mean error is about 16%, though maximum error can be as large as ∼100%. In general, the lower the sphericity, the poorer is the prediction