Author(s): Robert E. Thomas; Stuart J. Mclelland; Lynne E. Frostick
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Keywords: Dealiasing; Laminaria digitata; Turbulence; Vectrino II; Velocity Profile
Abstract: Over the past century, laboratory flume experiments have been used extensively to explore and elucidate micro- and meso-scale hydraulic and sediment transport processes. In recent decades, flume experiments have been increasingly applied to the study of ecohydraulic interactions: the interactions and feedbacks among organisms, fluid flow and the sediment substrate. However, questions remain regarding the comparability of observations gained in the field and the laboratory, and the limitations and applicability of laboratory experiments are not yet fully understood. In this paper, we describe research carried out by the participants in the PISCES work package of the HYDRALAB IV project that addresses some of these questions. To do this we quantified: 1.) the mean and turbulent flow field within a vegetated field prototype; 2.) the locations and biomechanical properties of the plants (see Paul and Henry, 2013); and 3.) the mean and turbulent flow field after plants were completely removed. These measurements will be repeated within a 1: 1 replica of the prototype in the 11 m long × 6 m wide Total Environment Simulator of the University of Hull. We selected an 11 m long × 6 m wide region of a tidal inlet, the Hopavagen Bay field station of NTNU, Sor-Trondelag, Norway to replicate the flume dimensions. Two Laminaria digitata specimens ~0. 30 m apart were selected for detailed study and a 2 m long × 8 m wide frame was oriented around them by enforcing zero cross-stream discharge at the upstream edge, which was ~0. 40 m upstream of the algae. Within this frame, a profiling ADV (Nortek Vectrino II) was used to collect velocity profiles, each composed of up to seven 35 mm-high profiles collected for 240 s at 100 Hz, at a streamwise spacing of 0. 25 m and cross-stream spacing of 0. 20 m. These were collected at 45 streamwise intervals of 1. 5 m. Velocity profile measurements were repeated over a sparser grid after the planform locations. Within the 11 × 6 m region surrounding the frame an ADCP survey was undertaken at of the algae, the streamwise (
Year: 2013