Flow-plant interactions at a leaf scale

effects of leaf shape, serration, roughness and flexural rigidity

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

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

The effects of leaf shape, serration, roughness and flexural rigidity on drag force imposed by flowing water and its time variability were experimentally studied in an open-channel flume at seven leaf Reynolds numbers ranging from 5 to 35 x 10(3). The study involved artificial leaves of the same surface area but with three shapes ('elliptic', 'rectangular' and 'pinnate'), three flexural rigidities, smooth-edge and sawtooth-like serration, and three combinations of surface roughness (two-side rough, one-side rough/one-side smooth, and two-side smooth). Shape was the most important factor determining flow-leaf interactions, with flexural rigidity, serration and surface roughness affecting the magnitude but not the direction of the effect on drag control. The smooth-edge elliptic leaf had a better hydrodynamic shape as it experienced less drag force, with the rectangular leaf showing slightly less efficiency. The pinnate leaf experienced higher drag force than the other leaves due to its complex geometry. It is likely that flow separation from 12 leaflets of the pinnate leaf prevented leaf reconfiguration such as leaflets folding and/or streamlining. Flexural rigidity strongly influenced the leaf reconfiguration and augmented the serration effect since very rigid leaves showed a strong effect of serration. Furthermore, serration changed the turbulence pattern around the leaves by increasing the turbulence intensity. Surface roughness was observed to enhance the drag force acting on the leaf at high Reynolds numbers. The results also suggest that there are two distinctly different flow-leaf interaction regimes: (I) regime of passive interaction at low turbulence levels when the drag statistics are completely controlled by the turbulence statistics, and (II) regime of active interaction at high turbulence levels when the effect of leaf properties on the drag statistics becomes comparable to the turbulence contribution.

Original languageEnglish
Pages (from-to)267-286
Number of pages20
JournalAquatic Sciences
Volume74
Issue number2
Early online date14 Jul 2011
DOIs
Publication statusPublished - Apr 2012

Keywords

  • Aquatic plants
  • Leaves
  • Drag force
  • Reconfiguration
  • Flexural rigidity
  • River flow
  • Fresh-water macrophytes
  • Drag
  • Vegetation
  • Hydrodynamics
  • Resistance
  • Winds

Cite this

Flow-plant interactions at a leaf scale : effects of leaf shape, serration, roughness and flexural rigidity. / Albayrak, Ismail; Nikora, Vladimir; Miler, Oliver; O'Hare, Matthew.

In: Aquatic Sciences, Vol. 74, No. 2, 04.2012, p. 267-286.

Research output: Contribution to journalArticle

Albayrak, Ismail ; Nikora, Vladimir ; Miler, Oliver ; O'Hare, Matthew. / Flow-plant interactions at a leaf scale : effects of leaf shape, serration, roughness and flexural rigidity. In: Aquatic Sciences. 2012 ; Vol. 74, No. 2. pp. 267-286.
@article{b958969cd1d94fdf869602801e3de599,
title = "Flow-plant interactions at a leaf scale: effects of leaf shape, serration, roughness and flexural rigidity",
abstract = "The effects of leaf shape, serration, roughness and flexural rigidity on drag force imposed by flowing water and its time variability were experimentally studied in an open-channel flume at seven leaf Reynolds numbers ranging from 5 to 35 x 10(3). The study involved artificial leaves of the same surface area but with three shapes ('elliptic', 'rectangular' and 'pinnate'), three flexural rigidities, smooth-edge and sawtooth-like serration, and three combinations of surface roughness (two-side rough, one-side rough/one-side smooth, and two-side smooth). Shape was the most important factor determining flow-leaf interactions, with flexural rigidity, serration and surface roughness affecting the magnitude but not the direction of the effect on drag control. The smooth-edge elliptic leaf had a better hydrodynamic shape as it experienced less drag force, with the rectangular leaf showing slightly less efficiency. The pinnate leaf experienced higher drag force than the other leaves due to its complex geometry. It is likely that flow separation from 12 leaflets of the pinnate leaf prevented leaf reconfiguration such as leaflets folding and/or streamlining. Flexural rigidity strongly influenced the leaf reconfiguration and augmented the serration effect since very rigid leaves showed a strong effect of serration. Furthermore, serration changed the turbulence pattern around the leaves by increasing the turbulence intensity. Surface roughness was observed to enhance the drag force acting on the leaf at high Reynolds numbers. The results also suggest that there are two distinctly different flow-leaf interaction regimes: (I) regime of passive interaction at low turbulence levels when the drag statistics are completely controlled by the turbulence statistics, and (II) regime of active interaction at high turbulence levels when the effect of leaf properties on the drag statistics becomes comparable to the turbulence contribution.",
keywords = "Aquatic plants, Leaves, Drag force, Reconfiguration, Flexural rigidity, River flow, Fresh-water macrophytes, Drag , Vegetation, Hydrodynamics, Resistance, Winds",
author = "Ismail Albayrak and Vladimir Nikora and Oliver Miler and Matthew O'Hare",
year = "2012",
month = "4",
doi = "10.1007/s00027-011-0220-9",
language = "English",
volume = "74",
pages = "267--286",
journal = "Aquatic Sciences",
issn = "1015-1621",
publisher = "Birkhauser Verlag Basel",
number = "2",

}

TY - JOUR

T1 - Flow-plant interactions at a leaf scale

T2 - effects of leaf shape, serration, roughness and flexural rigidity

AU - Albayrak, Ismail

AU - Nikora, Vladimir

AU - Miler, Oliver

AU - O'Hare, Matthew

PY - 2012/4

Y1 - 2012/4

N2 - The effects of leaf shape, serration, roughness and flexural rigidity on drag force imposed by flowing water and its time variability were experimentally studied in an open-channel flume at seven leaf Reynolds numbers ranging from 5 to 35 x 10(3). The study involved artificial leaves of the same surface area but with three shapes ('elliptic', 'rectangular' and 'pinnate'), three flexural rigidities, smooth-edge and sawtooth-like serration, and three combinations of surface roughness (two-side rough, one-side rough/one-side smooth, and two-side smooth). Shape was the most important factor determining flow-leaf interactions, with flexural rigidity, serration and surface roughness affecting the magnitude but not the direction of the effect on drag control. The smooth-edge elliptic leaf had a better hydrodynamic shape as it experienced less drag force, with the rectangular leaf showing slightly less efficiency. The pinnate leaf experienced higher drag force than the other leaves due to its complex geometry. It is likely that flow separation from 12 leaflets of the pinnate leaf prevented leaf reconfiguration such as leaflets folding and/or streamlining. Flexural rigidity strongly influenced the leaf reconfiguration and augmented the serration effect since very rigid leaves showed a strong effect of serration. Furthermore, serration changed the turbulence pattern around the leaves by increasing the turbulence intensity. Surface roughness was observed to enhance the drag force acting on the leaf at high Reynolds numbers. The results also suggest that there are two distinctly different flow-leaf interaction regimes: (I) regime of passive interaction at low turbulence levels when the drag statistics are completely controlled by the turbulence statistics, and (II) regime of active interaction at high turbulence levels when the effect of leaf properties on the drag statistics becomes comparable to the turbulence contribution.

AB - The effects of leaf shape, serration, roughness and flexural rigidity on drag force imposed by flowing water and its time variability were experimentally studied in an open-channel flume at seven leaf Reynolds numbers ranging from 5 to 35 x 10(3). The study involved artificial leaves of the same surface area but with three shapes ('elliptic', 'rectangular' and 'pinnate'), three flexural rigidities, smooth-edge and sawtooth-like serration, and three combinations of surface roughness (two-side rough, one-side rough/one-side smooth, and two-side smooth). Shape was the most important factor determining flow-leaf interactions, with flexural rigidity, serration and surface roughness affecting the magnitude but not the direction of the effect on drag control. The smooth-edge elliptic leaf had a better hydrodynamic shape as it experienced less drag force, with the rectangular leaf showing slightly less efficiency. The pinnate leaf experienced higher drag force than the other leaves due to its complex geometry. It is likely that flow separation from 12 leaflets of the pinnate leaf prevented leaf reconfiguration such as leaflets folding and/or streamlining. Flexural rigidity strongly influenced the leaf reconfiguration and augmented the serration effect since very rigid leaves showed a strong effect of serration. Furthermore, serration changed the turbulence pattern around the leaves by increasing the turbulence intensity. Surface roughness was observed to enhance the drag force acting on the leaf at high Reynolds numbers. The results also suggest that there are two distinctly different flow-leaf interaction regimes: (I) regime of passive interaction at low turbulence levels when the drag statistics are completely controlled by the turbulence statistics, and (II) regime of active interaction at high turbulence levels when the effect of leaf properties on the drag statistics becomes comparable to the turbulence contribution.

KW - Aquatic plants

KW - Leaves

KW - Drag force

KW - Reconfiguration

KW - Flexural rigidity

KW - River flow

KW - Fresh-water macrophytes

KW - Drag

KW - Vegetation

KW - Hydrodynamics

KW - Resistance

KW - Winds

U2 - 10.1007/s00027-011-0220-9

DO - 10.1007/s00027-011-0220-9

M3 - Article

VL - 74

SP - 267

EP - 286

JO - Aquatic Sciences

JF - Aquatic Sciences

SN - 1015-1621

IS - 2

ER -