Effect of instantaneous local solid volume fraction on hydrodynamic forces in freely evolving particle suspensions

Particle Resolved Simulations (PRS) for freely evolving sphere suspensions at solid volume fractions (φ) between 0.1 and 0.4, Reynolds number Re from 10 to 300 and particle-fluid density ratios ρsρf of 2, 10 and 100 are used to investigate the effect of Voronoi tessellation based particle local solid volume fraction (φv)on particle drag and lateral forces. Findings reveal the instantaneous suspension mean drag force is positively correlated with the variance of φv among particles in the suspension. It is also shown that using the conditioned instantaneous φv of each particle in existing mean drag force correlations can significantly improve the prediction accuracy. Suspension mean lateral force ranges up to 60 % of the drag force while individual particles exhibit values as high as 90 % of the drag force. An instantaneous lateral force correlation is proposed based on suspension-averaged flow variables and φv. [Display omitted] •Particle Resolved Simulations are performed for freely evolving sphere suspensions.•A Voronoi tessellation based local solid fraction is defined for each particle.•Suspension-mean drag force correlates positively with local solid fraction variance.•Using local solid fraction in drag correlations improves prediction accuracy.•The significance of lateral force is highlighted and its correlation is developed.