$198,202; NSF Engineering Research Initiation (ERI)

Wake interactions past two roughness elements in close proximity
Principal Investigator: Ali Hamed, assistant professor of mechanical engineering

PI Hamed aims to quantify and understand the wake interactions between two roughness elements (or obstacles) in close proximity under incoming turbulent flow. Though the presence of two roughness elements in an otherwise smooth surrounding is commonly encountered in environmental and engineering applications (e.g. two dunes in close proximity and two rivets in close succession on an engineered surface), the wake interactions between them are not well understood. Understanding these interactions is important because they govern critical flow features, including drag and turbulence. Using state-of-the-art instrumentation, including a high-speed volumetric particle image velocimetry (PIV) system acquired through an NSF Major Research Instrumentation grant (NSF Award ID: 1919570), flow measurements will be taken for a wide range of configurations. Through this project, PI Hamed will provide hands-on, transformative research experiences for 4-6 undergraduates each year and will introduce additional students to this research by incorporating aspects of this work into lectures and laboratory-based courses.

The overall objectives of this research are to: 1) quantify the flow interactions between the wakes of the two cylindrical roughness elements; 2) characterize the vortical structures shed from isolated cylindrical roughness elements and identify the modifications to these structures due to the introduction of an upstream cylinder; 3) investigate the effects of additional upstream elements (i.e., sheltering by 2, 3, and 4 upstream elements) on the captured flow physics; 4) quantify the roughness-induced perturbation to the boundary layer and its coherent structures; and 5) distill a spatiotemporally-resolved flow description that illustrates sheltering flow physics across a wide range of arrangements.