Abstract
A threedimensional boundarylayer model of shallowwater flows assuming hydrostatic pressure with negligible numerical diffusion and wave damping has been extended to turbulent flow. A standard twolayer mixinglength model determines vertical length scales. The horizontal mixing length is made a multiple β of the vertical value and β is determined from comparison with experiment. Eddy viscosity is of a general threedimensional form where, for example, the horizontal mixing length and associated strain rates determine the magnitude of eddy viscosity and hence vertical mixing (and vice versa). Direct comparison is made with previous experiments for subcritical flow around a conical island of small side slope which exhibits the transition from a vigorous vortexshedding wake to a steady recirculating wake as the stability parameter, St, is increased. The value of β influences wake structure, particularly for stability parameters close to the critical (the value at which the wake becomes steady or stable). The critical value in the experiments was 0.4 and this was reproduced in the model with β = 6. Vortex shedding patterns with St = 0.26 and 0.36 were qualitatively reproduced. The flows were subcritical with an onset Froude number of about 0.2, with values approaching 0.60.7 in areas where depthaveraged vorticity magnitude was also greatest, at a small distance from the wet/dry intersection. At this intersection, depthaveraged vorticity approached zero while potential vorticity (depthaveraged vorticity/depth) was at a maximum, indicating the importance of the intersection as an origin for vorticity.
Original language  English 

Title of host publication  Journal of Fluid MechanicsJ. Fluid Mech. 
Pages  369384 
Number of pages  15 
Publication status  Published  25 Nov 2003 
Event  IAHR Symposium on Shallow Flows, Delft (selected for publication in a special volume: Shallow Flows, Balkema, The Netherlands)  Duration: 1 Jan 1824 → … 
Conference
Conference  IAHR Symposium on Shallow Flows, Delft (selected for publication in a special volume: Shallow Flows, Balkema, The Netherlands) 

Period  1/01/24 → … 
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Accelerated development of a tidal stream energy industry
Peter Stansby (Participant), David Apsley (Participant), Timothy Stallard (Participant) & Imran Afgan (Participant)
Impact: Economic, Environmental, Technological