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Laboratory measurements of flow and turbulence in discontinuous distributions of ligulate seagrass.

Research output: Contribution to journalJournal article

<mark>Journal publication date</mark>1/07/2007
<mark>Journal</mark>Journal of Hydraulic Engineering
Issue number7
Number of pages11
Pages (from-to)750-760
<mark>Original language</mark>English


Turbulent flow characteristics were investigated in laboratory flume studies of a ligulate plant canopy interrupted by a gap representing discontinuities observed in seagrass prairies. The reliability of velocity measurements obtained using an acoustic Doppler velocimeter within the canopy was shown using specifically designed experiments. In relatively fast flow (mean velocity 5.5 cm s−1), the mean flow profile was logarithmic above the canopy, had an inflection point near its top, and uniformly low values within it. Within the gap, a recirculation cell formed. Reynolds stress maxima were approximately coincident with the mean flow inflection point. Quadrant analysis revealed an ejection-dominated upper layer, a sweep-dominated region around the top of the canopy and within the gap, and no dominant quadrant within the canopy. In slower flow (mean velocity 1.7 cm s−1) the plants were quasiemergent and the flow fields more uniform. Sweeps similarly dominated the region near the top of the canopy and within the gap. In both flows, autocorrelation of longitudinal velocity fluctuations showed a Lagrangian time scale maximum at the downstream end of the gap.

Bibliographic note

AF's roles: formulated the idea, co-led the discussion and interpretation of results, wrote a significant portion of text. RAE_import_type : Journal article RAE_uoa_type : Earth Systems and Environmental Sciences