Simple and General Formula for the Settling Velocity of Particles

A simple, robust, and general formula for the settling velocity of a particle is presented, taking into account the shape and roundness of the particles. It is based on the two asymptotic behaviors of the drag coefficient for low and high Reynolds numbers, respectively. The three coefficients in the proposed equation were fitted for different shape and roundness using explicit relationships. The proposed relationship yields the best results among the studied formulas for many kind of particles with various sizes, shapes, roundnesses, and densities. This formula could therefore be applied to any particle.