Author(s): Daniel G. Macdonald; G. H. Jirka
Linked Author(s):
Keywords: No Keywords
Abstract: The wakes behind simple headland shaped objects in shallow open channel flow were observed in a laboratory experiment using Planar Laser Induced Fluoresence (PLIF) flow visualization. Various wake characteristics, including recirculation zone length, wake half width, and flushing efficiency, were measured and evaluated as a function of a dimensionless shallowness parameter, S=c_f D/H, where cf is a friction coefficient, D the cross stream dimension of the obstruction, and H the fluid depth. As the S value increased, representing a transition from the deep limit to the shallow limit, the shape of the generic headland wake recirculation zone was observed to deform from an elongated, elliptical shape towards a more streamlined tear drop shape. Simultaneously, in the downstream portion of the wake, average wake width decreased, while transport of dye in the wake tended towards increasingly discreet pockets of dye concentration. Flushing efficiency of the recirculation zone was also found to increase as the shallowness of the flow increased.
Year: 1997