Author(s): David Plew; Roger Nokes; Jan Noering; Micah Kenall-Grant
Linked Author(s):
Keywords: Canopies; Stratified flow; Aquaculture
Abstract: Large-scale marine shellfish aquaculture creates artificial canopies that can influence currents and interact with stratification. A key difference between artificial aquaculture canopies and most natural vegetation canopies is that the aquaculture structures are suspended from the surface rather than attached to the bed. Drag from both the bed and the suspended canopy can have strong influences on the flow, whereas bed friction is not significant in most canopies located on the bed. Suspended canopies have received little attention in comparison to canopies of emergent or submerged vegetation, yet understanding their effects is essential to predicting likely environmental impacts of aquaculture. Data from laboratory experiments are presented which explore aspects of the flow through and around suspended canopies. The laboratory experiments, using both acoustic Doppler and2D particle tracking velocimetry, also give further details of the flow structure which may be separated vertically into a benthic boundary layer, a canopy shear layer, and an internal canopy layer. The interactions between a canopy and two-layer stratification are also investigated in a separate experiment in order to explore how stratification influences diversion of flow beneath the canopy. While this work is preliminary, early results illustrate the importance of the (internal) Froude number on the response of the stratification.
Year: 2010