The direct numerical simulation of a surface mounted cube in a channel flow at a Reynolds number of 5610 based on the cube height and bulk velocity was performed using the fifth-order compressible finite difference code OVERFLOW on overset chimera grids. Numerical simulation results are compared with and analyzed in light of published numerical and experimental results. The comparison of the time averaged results and turbulent statistics to previous DNS and experimental results validates the DNS procedure employed. Additionally, this analysis leads to recommendations on the settings of inlet and boundary conditions and the simulation domain to carry out a DNS that better conforms to the experimental conditions. An analysis of the turbulent quantities in the wake region indicates a break down of the isotropic turbulence assumption in high shear flows. The time averaged data revealed a system of six horseshoe vortices upstream of the cube, two counter-rotating vortices along the sides of the cube, and an arch-shaped vortex downstream of the cube.

This study investigated the unsteady acceleration aerodynamics of bluff bodies through the study of a channel mounted square cylinder undergoing free-stream acceleration of ± 20 m / s 2 with Reynolds numbers spanning 3.2e4 to 3.6e5. To achieve this, a numerical simulation was created with a commercial finite volume unstructured computational fluid dynamics code, which was first validated using Improved Delayed Detached Eddy Simulation against experimental and direct numerical simulated results. Then, the free stream conditions were subjected to a periodic velocity signal where data were recorded and ensemble averaged over at least 30 distinct acceleration and deceleration data points. This enabled the comparison of body forces and flow field variations among accelerating, steady and decelerating free-stream conditions. Body force analysis determined that decelerating and accelerating drag forces varied −47% and 44%, respectively, in comparison to steady free-stream conditions. In addition, several differences were also observed and explored such as near-body flow structures, wake dynamics, Kármán vortices and vorticity production during the aforementioned conditions. The primary interest of this study was for the future application towards road vehicles for predictive dynamic modeling and aerodynamic development.