Hydraulics/Hydrology Seminar Series
Multiple flow regimes and bistability in open channel flows over a step (or weir structure)
Professor of Civil Engineering
Tuesday, January 24, 2017
The open-channel flow just downstream of a drop or backward-facing step arises in various hydraulic structures, and has been observed to exhibit qualitatively different characteristics under different conditions or even under the same (upstream and downstream) conditions. A laboratory study, focusing on a subcritical upstream flow becoming critical just upstream of the step, was conducted to examine the conditions under which the two main flow regimes, a surface-flow regime and an impinging-jet regime, could stably occur. A region was found under which both regimes were possible for the same upstream and downstream conditions, and which thus would allow for hysteretic behavior where the flow regime could be history-dependent. Other similar flows, such as some weir flows, were also studied in light of the present results.