Atmospheric boundary layer modeling in a short wind tunnel

The aim of the study was to analyze and design through experimental and numerical investigations a passive device to control the development of the boundary layer in an existing short wind tunnel to reproduce conditions representative of an atmospheric boundary layer for wind engineering applications. The current main use of the tunnel being for automotive and train aerodynamics, constrained the design to look for a reversible solution. The approach followed was then to install a grid of horizontal bars of squared cross-section with different dimensions at the entrance of the experimental chamber. The distribution of the bars was selected to be symmetric with respect to the horizontal longitudinal mid-plane of the tunnel. The approach has been validated through experimental measurements by hot-wire anemometry and numerical simulations based on finite volume RANS of the full wind tunnel geometry. The analysis showed that the grid acting as a passive flow control device was effective to reproduce in a short wind tunnel the main characteristics of an atmospheric boundary layer.