EFFECT OF THE UPSTREAM EDGE ROUNDING ON THE FLOW AROUND A 3:1 RECTANGULAR CYLINDER

The present work experimentally and numerically investigates the dynamics of the flow around a rectangular cylinder having a chord-to-depth ratio equal to 3. In particular, this thesis aims at analyzing the effect of the upstream edge rounding on the mean and instantaneous flow features. Experiments and simulations are carried out at Reynolds number Re = 40000, based on the cylinder transverse length D and the freestream velocity U. Five values of the upstream edge rounding are considered from r/D = 0 (sharp edges) in simulations and r/D = 0.0005 in experiments to r/D = 0.1104 in both investigations. Experiments are carried out in the subsonic wind tunnel of the Department of Civil and Industrial Engineering of the University of Pisa. Pressure distributions are measured through differential pressure transducers and the velocity field through hot-wire anemometry. Numerical investigations are performed by using the open-source incompressible flow solver Nek5000, based on a high-order spectral element method. Upstream edge roundings have a significant impact on the flow pattern aside and downstream of the considered body. In particular, the mean recirculation region along the lateral side of the body slightly increases for small values of the roundings, whereas it becomes shorter for higher values of them. As for the instantaneous flow, the effects of upstream edge rounding on Kelvin-Helmholtz instability and vortex shedding frequency are described