Numerical Investigation on the Ground Speed Effect around a Square Cylinder near the Ground

Abstract

The unsteady flow field around a square cylinder is investigated by solving the two-dimensional Reynolds-averaged Navier-Stokes equations with ε-SST turbulence model at Re = 20,000 with changes of gap height, from G/D = 0.1 to G/D = 2.0, and ground speed, from 0 to U∞, respectively. Through analysis on the vortex strength, lift and drag coefficients, and the Strouhal number of a square cylinder, it is found out that the separation bubble located on the ground behind a square cylinder is the core reason which makes significant differences of flow characteristics between the stationary and moving ground. Also the separation bubble seems to prevent the sharp transition from steady flow to periodic vortex shedding.