Shape descriptors - settling characteristics of irregular shaped particles

Abstract

Shape descriptor is a concise yet informative representation to address challenging issues in areas as diverse as engineering, medicine and biology. The prediction of settling velocity and drag coefficient of non-spherical shaped particles as close as possible to their actual behavior has been an interest to engineering community. Often, correlations developed for predicting settling velocity do not accomplish the estimation of the drag coefficient. The solid particle shape characteristics need to be assessed with definitions of NRep and Ar suitably. Terfous et al. (2013, Predicting the Drag Coefficient and Settling Velocity of Spherical Particles. Powder Technology. 239:12–20) presented a direct prediction of settling velocity for a spherical particle correlating NRep and Ar with good accuracy over a wide range of NRep. In this paper, appropriate scaling factors are suggested to represent NRep and Archimedes number and compared with data from in-house experiments and from published literature. The prediction is found to be in fair agreement with data from published work (cuboid and cylinders with various aspect ratio) and experimental data generated in-house with irregular shaped solid particles viz., sand, plastic, coal, raagi (Millets) and mustard seeds.HighlightsEstimation of settling velocity of different irregular shaped particles viz., sand, plastic, coal, mustard, raagi etc.A modified correlation to predict the settling velocity of irregular shaped particle by including shape descriptors viz, circularity, volume fraction, volume projected area diameter.The average error between the predicted and experimental data is found to be around 8.3%.