Characterization of lift force and torque in prolate ellipsoid suspensions

Abstract

The paper derives correlations for lift force and fluid torques acting on stationary prolate ellipsoid suspensions of aspect ratio (AR) 2.5, 5, and 10 subjected to uniform flow. Particle Resolved Simulations (PRS) are conducted on a suspension of infinite extent in two directions for Reynolds number 10 ≤ Re ≤ 200 and solid fractions (φ) between 0.1 ≤ φ ≤ 0.3.The suspension-mean lift-to-drag ratio varies between 7% to 14% at Re=10 which increases to 14% ~ 22% at Re=200. The torque-induced tip rotational acceleration can reach 38% ~ 85% of drag-induced translational acceleration at Re = 200. Single particle lift force and torque correlations of (Fröhlich et al., 2020) are modified and adapted to predict current angular-mean lift and torque data. The resulting lift correlation captures the PRS data within an average deviation below 7%. Torque exhibits a somewhat more complex dependency at AR = 10 than the assumed sinθ ∙ cosθ variation but nevertheless the correlations predict angular-mean values with mean relative deviations of 16.6% at AR = 10.