Bluff-body wakes and turbulent flows

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"Bluff bodies" have non-streamlined shapes and very high drag coefficients. Flow around a bluff body is complex, and is characterized by a large region of separated flow, where the flow does not follow the shape of the body. In the low-pressure wake downstream of the body, which may be unsteady or turbulent, the phenomenon of "vortex shedding" occurs as vortices are periodically released from the surface of the body. Under certain conditions, vortex shedding may cause unwanted structural motion known as "flow-induced vibration." The main scientific goal of my research program is to advance the physical understanding of bluff-body wakes, where the emphasis is the flow around surface-mounted, finite-height bluff bodies, such as finite circular cylinders, finite square prisms, and rooftop-mounted chimney stacks. I want to better understand the fundamental relationships between the wake-generating body and the local flow field, and how the near wake is influenced by alterations to the body shape, its proximity to other bluff bodies, and the presence of the ground plane. For the rooftop-mounted stack (an "elevated jet in cross-flow"), I want to better understand how the stack jet flow regimes affect the forces experienced by the stack and the flow in the stack wake. A second scientific goal of my research is to better understand the effects of surface roughness on wall-bounded turbulent shear flows, specifically the plane turbulent wall jet. Turbulent wall jets are encountered in the film cooling of turbine blades and in slotted flaps on airplane wings. For this flow, I want to better understand the effects of surface roughness and Reynolds number on the skin-friction drag acting on the wall. For both main research areas, the expected research contributions will include new experimental data for engineering design work, and new knowledge into the fundamentals of fluid flow behaviour. Both experimental and numerical modeling approaches will be used in the research program.