Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Laboratory measurements of flow and turbulence in discontinuous distributions of ligulate seagrass.
AU - Maltese, Antonino
AU - Cox, Eleanor
AU - Folkard, Andrew M.
AU - Ciraolo, Giuseppe
N1 - 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
PY - 2007/7/1
Y1 - 2007/7/1
N2 - 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.
AB - 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.
U2 - 10.1061/(ASCE)0733-9429(2007)133:7(750)
DO - 10.1061/(ASCE)0733-9429(2007)133:7(750)
M3 - Journal article
VL - 133
SP - 750
EP - 760
JO - Journal of Hydraulic Engineering
JF - Journal of Hydraulic Engineering
SN - 0733-9429
IS - 7
ER -