Flow-plant interactions at leaf, stem and shoot scales: drag, turbulence, and biomechanics

Albayrak, Ismail; Nikora, Vladimir; Miler, Oliver; O'Hare, Matthew

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Flow-plant interactions at leaf, stem and shoot scales: drag, turbulence, and biomechanics

Albayrak, Ismail ; Nikora, Vladimir ; Miler, Oliver ; O'Hare, Matthew

In: Aquatic Sciences, 2014, vol. 76, no. 2, p. 269-294

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Title

Flow-plant interactions at leaf, stem and shoot scales: drag, turbulence, and biomechanics

Author

Albayrak, Ismail. Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, Wolfgang-Pauli-Str. 27, 8093, Zurich, Switzerland
Nikora, Vladimir. School of Engineering, Fraser Noble Building, University of Aberdeen, AB24 3UE, Aberdeen, UK
Miler, Oliver. Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 301, 12587, Berlin, Germany
O'Hare, Matthew. Centre for Ecology and Hydrology Edinburgh, Bush Estate, Penicuik, EH26 0QB, Midlothian, UK

Document Type

Postprint

Language

English

Published in

Aquatic Sciences, 2014, vol. 76, no. 2, p. 269-294. Springer Basel

Other Version

Publisher's version : https://doi.org/10.1007/s00027-013-0335-2

Classification

Agriculture, Agronomy

Keywords

Aquatic plants ; Drag force ; Flow-plant interactions ; Plant reconfiguration ; Plant biomechanics ; Turbulent open-channel flow ; ADV : Acoustic Doppler velocimeter ; A : Reference area ; A f : Frontal projection area of plant ; A i : Characteristic plant diameter×lateral projection plant height ; A w : Total wetted area ; α : Vogel number ; B : Mean leaf width or mean stem diameter ; C d : Drag coefficient ; $$C_{d - FPL}$$ C d - F P L : Drag coefficient of laminar flat plate flow ; $$C_{d - FPT}$$ C d - F P T : Drag coefficient of turbulent flat plate flow ; $$C_{xy}$$ C x y : Covariance function ; CV : Coefficient of variation ; d : Characteristic plant diameter ; $$\Delta z$$ Δ z : Leaf ridge height ; $$\delta$$ δ : Viscous sublayer height ; $$\delta^{ + }$$ δ + : Normalised height of the viscous sublayer ; DMD : Drag measurement device ; E : ‘Tension' Young's modulus ; Eb : ‘Bending' Young's modulus ; EI : Flexural rigidity ; f : Frequency ; f s : Sampling frequency ; F : Mean drag force ; $$F_{m}$$ F m : Total mean drag force (i.e., tip+leaf) ; $$\hat{F}_{m}$$ F ^ m : Instantaneous total drag force (i.e., tip+leaf) ; $$F_{t}$$ F t : Mean drag force acting on the rod tip ; $$\hat{F}_{t}$$ F ^ t : Instantaneous drag force acting at the rod tip ; h : Water depth ; h i : Height of the lateral projection of plant ; I : Second moment area ; K d : Kurtosis coefficient ; L : Leaf, stem or shoot length ; L f : Length of plant lateral projection ; LFTF : Leaf force transfer function ; LBL : Leaf boundary layer ; LVTF : Leaf velocity transfer function ; $$MR_{{\hat{F}_{m} u_{d} }}$$ M R F ^ m u d : Average of maximum cross-correlation coefficients between drag force and downstream velocity ; $$MR_{{u_{a} \hat{F}_{m} }}$$ M R u a F ^ m : Average of maximum cross-correlation coefficients between approach velocity and drag force ; $$MR_{{u_{a} u_{d} }}$$ M R u a u d : Average of maximum cross-correlation coefficients between approach velocity and downstream velocity ; n : Number of samples ; PSD : Power spectral density ; Q : Discharge ; $$R_{xy}$$ R x y : Cross-correlation function ; $$R_{{\hat{F}_{m} U_{d} }}$$ R F ^ m U d : Cross-correlation function between drag force and downstream velocity ; $$R_{{u_{a} \hat{F}_{m} }}$$ R u a F ^ m : Cross-correlation function between approach velocity and drag force ; $$R_{{u_{a} u_{d} }}$$ R u a u d : Cross-correlation function between approach and downstream velocities ; Re : Reynolds number ; Re h : Depth-based Reynolds number ; Re L : Plant length-based Reynolds number ; $$\text{Re}_{Lc}$$ Re L c : Critical Reynolds number for transition from laminar boundary layer to the turbulent boundary layer ; $$\rho$$ ρ : Fluid density ; $$\sigma_{d}$$ σ d : Standard deviation of drag force ; $$\sigma_{{u_{a} }}^{{}}$$ σ u a : Standard deviation of approach velocity ; $$\sigma_{{u_{d} }}$$ σ u d : Standard deviation of the downstream velocity ; $$\sigma_{m}^{2}$$ σ m 2 : Total variance of drag force ; $$\sigma_{t}^{2}$$ σ t 2 : Variance related to the rod tip ; $$\sigma_{{u_{a} }}^{2}$$ σ u a 2 : Variance of approach velocity ; S b : Flume bed slope ; S d : Skewness coefficient ; $$S_{{\hat{F}_{m} }}$$ S F ^ m : Power spectral density of drag force ; $$S_{{u_{a} }}$$ S u a : Power spectral density of approach velocity ; $$S_{{u_{d} }}$$ S u d : Power spectral density of downstream velocity ; SFTF : Shoot force transfer function ; SVTF : Shoot velocity transfer function ; STFTF : Stem force transfer function ; STVTF : Stem velocity transfer function ; t : Time ; $$\tau$$ τ : Time lag ; $$\tau_{0}$$ τ 0 : Mean shear stress at a leaf surface ; u : Instantaneous longitudinal velocity ; u′ : Fluctuating component of longitudinal velocity ; $$u_{*}$$ u ∗ : Friction velocity ; U : Time-averaged longitudinal velocity ; U a : Time-averaged velocity in front of a shoot or its parts ; U f : Undisturbed velocity integrated over A f ; U i : Undisturbed velocity integrated over h i ; U m : Cross-sectional average velocity ; $$\upsilon$$ υ : Fluid kinematic viscosity ; $$z^{ + }$$ z + : Leaf ridge Reynolds number ; $$\overline{{z^{ + } }}$$ z + ¯ : Average $$z^{ + }$$ z +

OAI-PMH Identifier

oai:doc.rero.ch:324886

Summary

Flow-plant interactions are experimentally investigated at leaf, stem, and shoot scales in an open-channel flume at a range of Reynolds numbers. The experiments included measurements of instantaneous drag forces acting on leaves, stems, and shoots of the common freshwater plant species Glyceria fluitans, complemented with velocity measurements, high-resolution video recordings, and biomechanical tests of leaf and stem properties. The analyses of bulk statistics, power spectral densities, transfer functions, and cross-correlations of measured velocities and drag forces revealed that flow characteristics, drag force, and plant biomechanical and morphological properties are strongly interconnected and scale-dependent. The plant element-flow interactions can be subdivided into two classes: (I) passive interactions when the drag variability is due to the time variability of the wetted and frontal areas and squared approach velocity (due to the large-scale turbulence); and (II) active interactions representing a range of element-specific instabilities that depend on the element flexural rigidity and morphology. Implications of experimental findings for plant biophysics and ecology are briefly discussed.

Flow-plant interactions at leaf, stem and shoot scales: drag, turbulence, and biomechanics

Albayrak, Ismail ; Nikora, Vladimir ; Miler, Oliver ; O'Hare, Matthew

In: Aquatic Sciences, 2014, vol. 76, no. 2, p. 269-294

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Flow-plant interactions at leaf, stem and shoot scales: drag, turbulence, and biomechanics

Albayrak, Ismail ; Nikora, Vladimir ; Miler, Oliver ; O'Hare, Matthew

In: Aquatic Sciences, 2014, vol. 76, no. 2, p. 269-294

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