Wave‐induced velocities inside a model seagrass bed

Luhar, Mitul; Coutu, Sylvain; Infantes, Eduardo; Fox, Samantha R.; Nepf, Heidi

doi:10.1029/2010jc006345

Cited by 167 publications

(309 citation statements)

References 67 publications

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“…For experiments without kelp, the correlation between horizontal and vertical wave orbital velocities Sũ uw wT was consistent with a partial standing wave due to a slight wave reflection from the downstream end of the flume. We were unable to determine from the measurements whether the model kelp caused a significant change in the wave stress gradient that could affect the current, like that described in Luhar et al (2010).…”

Section: Resultsmentioning

confidence: 97%

“…As the drag parameter aK D / v increases, the magnitude of G decreases only slightly but the phase of G is shifted, resulting in phase shifts in wave orbital velocities. If phase shifts in vertical and horizontal orbital velocity components are different, kelp drag could cause an effective wave stress, Sũ uw wT, that affects currents (Luhar et al 2010).…”

Section: Lsũmentioning

confidence: 99%

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Interaction of waves and currents with kelp forests (Macrocystis pyrifera): Insights from a dynamically scaled laboratory model

Rosman

Denny

Zeller

et al. 2013

Limnology & Oceanography

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The interaction of surface waves and currents with kelp forests was examined under controlled conditions using a dynamically matched 1/25-scale physical model in a laboratory flume. In experiments with kelp mimics, waves increased the time-averaged drag by a factor of 2 and altered the shape of current profiles. Relative motion between model kelp and water under waves increased wake generation of turbulence, resulting in turbulent kinetic energies 2-5 times larger, and eddy viscosities 20-50% larger, than for experiments without waves. Because mixing lengths were reduced to wake-scales in the model kelp forest, eddy viscosities were 25-50% smaller than when kelp was absent. In the model kelp-forest surface canopy where solid obstacles were most densely spaced, wave orbital velocities were reduced by , 10% from linear wave theory predictions. This decrease in wave orbital velocities is thought to result primarily from inertial forces exerted on water by model kelp. Stokes drift was reduced by , 20% as a result of the change in wave orbital velocities. Although hydrodynamics within kelp forests are more complex than in the laboratory experiments and a wide range of flow conditions can occur, laboratory results suggest that (1) kelp forest drag is increased by waves; (2) wave properties can be altered by drag and inertial forces; and (3) wake production of turbulence caused by waves may be the main source of turbulence in dense kelp stands. Interactions between kelp and waves must therefore be taken into account when developing models for drag and mixing in these systems.

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Section: Resultsmentioning

confidence: 97%

Section: Lsũmentioning

confidence: 99%

Interaction of waves and currents with kelp forests (Macrocystis pyrifera): Insights from a dynamically scaled laboratory model

Rosman

Denny

Zeller

et al. 2013

Limnology & Oceanography

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“…The force balance that determines in-canopy velocities depends on 3 factors: a shear stress imposed at the top of the canopy, drag exerted by the canopy, and -when waves are present -the inertial forces associated with that unsteadiness (Lowe et al 2005a, Luhar et al 2010. Luhar et al (2010) applied and streamlined the full rigid-canopy momentum balance model introduced by Lowe et al (2005a) to the case of a model canopy comprised of flexible elements.…”

Section: Canopy Flow Modelmentioning

confidence: 99%

“…Luhar et al (2010) applied and streamlined the full rigid-canopy momentum balance model introduced by Lowe et al (2005a) to the case of a model canopy comprised of flexible elements. In each of these approaches, canopy depth-averaged flow (Û) is described relative to undisturbed abovecanopy flow (U ∞ ) with the velocity ratio:…”

Section: Canopy Flow Modelmentioning

confidence: 99%

Uptake of dissolved inorganic nitrogen by shallow seagrass communities exposed to wave-driven unsteady flow

Weitzman

Aveni-Deforge²,

Koseff³

et al. 2013

Mar. Ecol. Prog. Ser.

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In natural seagrass systems, regular oscillatory motion -like that caused by surface wind-waves -enhances uptake of dissolved inorganic nitrogen (DIN) relative to current-driven, unidirectional flows. A mobile field flume was deployed to measure the uptake of DIN by intact shallow seagrass communities exposed to unidirectional, oscillatory, and combined flows. The flume volume was spiked with 15 N-labeled DIN to measure nutrient uptake rate constants for the entire system (S) and to determine height-specific nutrient uptake rates of seagrass epiphytes (ρ). In oscillatory and combined flows, S depended positively on the water speed, but also inversely on a modified Keulegan-Carpenter number (KC). This ratio compares the wave-orbital excursion distance to canopy element spacing. Experiments characterized by relatively low KC values were associated with significantly higher uptake efficiencies than experiments characterized by high KC values. Uptake efficiencies for high KC conditions were similar to those measured in comparable unidirectional flows. Measured canopy flow attenuation was also found to increase with KC, a result in line with expectations from a parameterized conceptual model. Damping variability alone could not explain the observed oscillatory flow uptake enhancement however, a result that seemingly highlights the role of both element flexural response and unsteady boundary layer mechanics in the exchange process. In all flow conditions, DIN uptake rates of epiphytes harvested from the bottom of the blades (ρ bot ) were lower than those for epiphytes harvested from the upper portion of the blades (ρ top ). While uptake by the top epiphytes exhibited flow dependency, uptake by bottom epiphytes did not.

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“…Recent experimental approaches (i.e. : Luhar et al, 2010) have revealed that the wave induced orbital velocity within the canopy was not significantly damped, revealing a relevant vertical motion within the plant field, pointing out the necessity of considering such aspect in the modeling.…”

Section: Introductionmentioning

confidence: 99%

Wave Attenuation Modelling by Submerged Vegetation: Ecological and Engineering Analysis

Maza

Lara

Ondiviela

et al. 2012

Int. Conf. Coastal. Eng.

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The correct address of wave characteristics in the vicinity of submerged vegetation is crucial to perform an ecological analysis. Although several attempts have been done in the past using an analytical approach or depth averaged models, the rigidity of the assumptions used to solve the physics produced limited application to real cases. The use of a NS model called IH-2VOF is used first to minimize the number of predefined assumptions for wave propagation and the non-linear interactions between waves and plants and second to explore the possibility to improve existing turbulence models to consider wave interaction with vegetation. The IH2-VOF model has been validated using large scale experiments developed by Stratigaki et al. (2011). The model has shown a high degree of accordance between the lab data and the numerical predictions in free surface evolution. Numerical predictions of the velocity field have been compared both over and inside the vegetation showing also a high degree of accordance. Drag coefficients obtained during the model calibration are in accordance with previous studies such as Mendez et al. (1999). The influence of wave height, wave period, water depth and patch density have been studied using additional numerical simulations with irregular waves. Both the wave period and the water depth have been revealed as the most important parameters in the modification of the flow patterns around the patch.

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Wave‐induced velocities inside a model seagrass bed

Cited by 167 publications

References 67 publications

Interaction of waves and currents with kelp forests (Macrocystis pyrifera): Insights from a dynamically scaled laboratory model

Interaction of waves and currents with kelp forests (Macrocystis pyrifera): Insights from a dynamically scaled laboratory model

Uptake of dissolved inorganic nitrogen by shallow seagrass communities exposed to wave-driven unsteady flow

Wave Attenuation Modelling by Submerged Vegetation: Ecological and Engineering Analysis

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