Turbulence measurements in tidal bore-like positive surges over a rough bed

TL;DRAbstract

A sudden rise of the water depth in an open channel flow creates a surge propagating in the channel called a positive surge. Positive surges can be observed as natural phenomena when a spring tide enters a funnel-shaped estuary under appropriate tidal and bathymetric conditions: the process is called a tidal bore. In this study, the free surface profile and the unsteady turbulent motion of positive surges were studied physically in a relatively large facility under controlled conditions based upon a Froude similarity. The experiments were conducted in a 12 m long 0.5 m wide rectangular channel mostly covered by a rough fixed gravel bed. The metrology included a combination of acoustic Doppler velocimeters (ADVs) and acoustic displacement meters (ADMs). The initially steady flow conditions were controlled by the water discharge, and the steady flow properties were investigated thorougly using a Pitot tube and ADV. The positive surge was generated by the fast closure of a downstream gate

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