Review-Drag Coefficients of Non-Spherical and Irregularly Shaped Particles

The knowledge of simple and relatively accurate closure equations for the drag coefficients of nonspherical particles is very important for Eulerian multiphase numerical codes that require such inputs for the solution of the momentum equation. However, the existing correlations for the drag coefficients are laden with high uncertainty, which propagates in the numerical results. This review paper examines critically the state of our knowledge of the drag coefficients of nonspherical particles starting with our understanding of the size and shape of particles. Lengthscales and other parameters that have been used to characterize sizes of nonspherical particles are presented. Shape factors and shape descriptors that have been used in past correlations are also presented together with an appraisal of their applicability. Several correlations that have been developed for the determination of the drag coefficients of nonspherical particles with regular and irregular shapes are also presented together with available information on their accuracy and applicability. Based on the review of the available correlations general recommendations are offered on the use of the correlations as closure equations and inputs in computatioal fluid dynamics (CFD) codes.

Automated summary

The knowledge of closure equations for the drag coefficients of nonspherical particles is crucial for numerical codes. However, the existing correlations for drag coefficients have high uncertainty. This review paper critically examines the understanding of size and shape of particles, presents shape factors and descriptors used in past correlations, and provides information on the accuracy and applicability of various drag coefficient correlations for nonspherical particles.