Investigation of drag, lift and torque for fluid flow past a low aspect ratio (1:4) cylinder

Abstract

Non-spherical objects exist in many multiphase applications but there is very limited data available on the fluid forces acting on these different shapes. This work derives correlations for drag, lift and torque coefficients for a single low aspect ratio 1:4 cylinder (tablet shaped object) placed at different incidence angles to the approach flow using direct numerical simulations (DNS). An Immersed Boundary Method (IBM) is used for deriving the force coefficients for 10 ≤ Re ≤ 300 and incidence angles 0° ≤ θ ≤ 90°. The method is validated by comparisons to existing data on spheres, to results from a body conforming grid, and through a grid independency study. The flow around the cylinder remains steady till Re = 200 θ ≤ 30°. The general correlation of Hölzer and Sommerfeld [1] for non-spherical particles, over predicts the drag coefficient for 0° < θ < 90° and the degree of over prediction increases with Reynolds number. The lift coefficient has a symmetric distribution about the maximum value at θ = 45° at Re = 10 but develops asymmetries in θ as Reynolds number increases. Contributions of pressure force and shear to drag and lift for each case is presented to provide a detailed view of the hydrodynamic forces on the object. The trends in the torque coefficient are similar to the lift coefficient reaching a maximum value near 45°. Correlations based the Reynolds number and incidence angle are developed for drag, lift and torque coefficients.