Turbulence in a wheat crop

Baines, Graham B. K.

doi:10.1016/0002-1571(72)90010-6

Cited by 17 publications

(4 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Turbulence spectra in plant canopies show the effects of shear forces and wake fiow from canopy elements (leaves, stems and trunks) superimposed on a complex cascade of disintegration of large atmospheric eddies into smaller ones (e.g. Baines, 1972;Finnigan & Raupach, 1987). Given the reduced wind speed in canopies, the TI is generally high, typically between 40 and 70% (Cionco, 1972).…”

Section: Turbulence In Canopy and Leaf Blmentioning

confidence: 99%

Tansley Review No. 59 Leaf boundary layers

1993

View full text Add to dashboard Cite

Studies of heat and mass exchange between leaves and their local environment are central to our understanding of plant‐atmosphere interactions. The transfer across aerodynamic leaf boundary layers is generally described by non‐dimensional expressions which reflect largely empirical adaptations of engineering models derived for flat plates. This paper reviews studies on leaves, and leaf models with varying degrees of abstraction, in free and forced convection. It discusses implecations of finding for leaf morphology as it affects – and is affected by – the local microclimate. Predictions of transfer from many leaves in plant communities are complicated by physical and physiological feedback mechanisms between leaves and their environment. Some common approaches, and the current challenge of integrating leaf‐atmosphere interactions into models of global relevance, are also briefly addressed.

show abstract

Section: Turbulence In Canopy and Leaf Blmentioning

confidence: 99%

Tansley Review No. 59 Leaf boundary layers

1993

View full text Add to dashboard Cite

show abstract

“…In wheat, Baines (1972) has measured turbulence with a single constant-temperature hot-wire anemometer positioned to minimize the effect of the crosswind component. Meroney (1968) conducted comparable studies in model canopies using a single constant-temperature hot-wire anemometer of unspecified directional sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Some observations of turbulence and turbulent transport within and above plant canopies

Shaw

Silversides

Thurtell

1974

Boundary-Layer Meteorol

102

View full text Add to dashboard Cite

Observations have been made of the structure of turbulence and turbulent exchange within plant canopy layers. A new three-dimensional anemometer was used to measure the eddy fluxes of heat and momentum, and the related cospectra, within and above a corn crop and above a red pine forest. Measured values of momentum and heat fluxes, at each height within the corn canopy, were relatively constant proportions of the flux above the canopy, for the period of a day's observation. Extensive regions obeying a -j power relation were found. Isotropy was found above the forest at high frequencies while above and within the corn crop, the ratios of the lateral and vertical spectral densities to the longitudinal component were less than the expected value in the -j region. In all situations, the vertical velocity spectra were more peaked than a 'universal' curve, particularly a vertical velocity spectrum from above the forest. It is suggested that the additional variance results from the mixing caused by the individual roughness elements. As expected, the spectra could not be normalized using the height above the soil surface to calculate a non-dimensional frequency, but scaling heights were estimated by matching the frequencies of the peak of each curve with that of the 'universal' curve. Cospectra of uw and wT within the corn canopy were of similar shape and frequency regime, and were basically similar in shape to cospectra above the crop. All of the cospectra were more sharply peaked than 'universal' cospectral curves.

show abstract

“…In the second set of experiments the flow in the wind tunnel was made turbulent. These conditions are much more like those known to exist in and over vegetation (for example, see Baines, 1972), though no attempt was made to reproduce precisely the structure of natural turbulence. In tliese experiments the signal indicated considerable turbulence at 1.35 m s~\ and fully-developed turbulence at 2.3 m s'' {a = 8% at 2.3 m s' \ Fig.…”

mentioning

confidence: 99%

The turbulent boundary layer over a flapping Populus leaf

Grace¹

1978

Plant Cell & Environment

View full text Add to dashboard Cite

The air‐flow regime over a Populus leaf was investigated using a constant temperature hot‐film sensor which could be glued on the abaxial surface. The leaf was exposed to a laminar or turbulent flow of air in a wind‐tunnel, while being free to undergo normal motion. In the laminar air‐flow the boundary layer remained laminar, despite the fluttering of the leaf, until a Reynolds number of 2.3 × 104 was reached. When the air incident on the leaf was made turbulent, to resemble natural conditions, the boundary layer became turbulent at a Reynolds number of 0.4 × 104. The experiments suggest that the boundary layers over leaves are always turbulent in the natural wind.

show abstract

Turbulence in a wheat crop

Cited by 17 publications

References 7 publications

Tansley Review No. 59 Leaf boundary layers

Tansley Review No. 59 Leaf boundary layers

Some observations of turbulence and turbulent transport within and above plant canopies

The turbulent boundary layer over a flapping Populus leaf

Contact Info

Product

Resources

About