Velocity fluctuations in the wake behind wind breakers and at the edge of the shear layer, and their correlations with the free stream

Boldes, Ulfilas; Colman, J.; Mora, Vicente Nadal; Zumarraga, A.

doi:10.1016/0167-6105(95)00011-9

Cited by 3 publications

(3 citation statements)

References 14 publications

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“…Seginer13 suggested calculation of drag coefficient of a windbreak from the horizontal velocity field where direct wind‐load measurement was not possible. The wind‐tunnel and field experiments of Boldes et al 14 to investigate characteristics of the shelter geometry and the boundary shear turbulence clarified the velocity shifts (1) in the wake behind windbreaks and (2) at the edge of shear layers versus that of the free stream.…”

Section: Windbreaksmentioning

confidence: 99%

“…Artificial windbreaks can be made of virtually any material. Some of the artificial windbreaks in the reviewed literature were as follows: two lines of cloth shelterbelt, 60% porosity;25 46% vertically spaced webbing with vertical ties;26 artificial model sorghum in a wind tunnel;27 wire mesh shelter of 70% porosity;14 50% open synthetic material (curtain) in the field;28 coarse lattices and perforated plates in a wind tunnel;29 portable slat‐fence windbreak of 50% porosity;30 vertical wooden slats of various porosities in field experiments;31, 32 and medium porosity Sarlon cloth shelterbelt19, 33 in the field. More recently, it has been reported that wind tunnel studies of airborne spray with nylon screen of c 50% porosity attained maximum capture efficiency (Fox R D, Zhu H and Reichard D L, pers comm, 1998).…”

Section: Windbreaksmentioning

confidence: 99%

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Windbreaks as a pesticide drift mitigation strategy: a review

Uçar

Hall

2001

Pest Management Science

118

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The use of natural and artificial barriers to mitigate pesticide drift from agricultural and forest applications is discussed. This technique has been considered as an alternative to current methods at a time when environmental concerns are under great public scrutiny. There has been a variety of research experiments on this subject from New Zealand to The Netherlands which have documented reductions in spray drift of up to 80-90%. However, there are still enormous data gaps to utilize this method accurately. The aerodynamic factors of wind barriers and shelter effects on crop growth and yield have been well investigated. In contrast, some of the important aspects of drift mitigation, e.g. porosity and turbulence, have been difficult to obtain and no standard methodologies are currently available to evaluate and classify windbreaks and shelterbelts or to determine their efficiency in reducing drift. Thus there is a significant opportunity to incorporate windbreaks into the tool set of drift mitigation tactics. Government policies, initiatives, legislation, etc, which currently address water quality, BMP, stewardship, buffers, etc, are issues which so far have not included windbreaks as a valuable drift mitigation strategy.

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Section: Windbreaksmentioning

confidence: 99%

Section: Windbreaksmentioning

confidence: 99%

Windbreaks as a pesticide drift mitigation strategy: a review

Uçar

Hall

2001

Pest Management Science

118

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“…De nombreux chercheurs (Heisler et Dewalle, 1988 ;Mc Aneney et Judd, 1991 ;Argent, 1992 ;Boldes et al, 1995 ;Geiger, 1995 ;Wang et Takle, 1995 ;Patton et Shaw, 1998) ont étudié l'influence aérodynamique des haies brise-vent en laboratoire (par exemple avec des simulations en soufflerie). Mais l'influence des haies brise-vent sur les paramètres météorologiques favorables à un fort refroidissement de l'air superficiel est moins connue.…”

Section: Introductionunclassified

Impact des haies brise-vent sur le gel printanier en arboriculture

Quénol

Beltrando

2006

Climatologie

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Afin de mieux cerner les facteurs explicatifs de la variabilité spatiale et temporelle du gel en milieu clos, un protocole de mesure de la température en indice actinothermique (IA), des écoulements de l'air superficiel et de l'humidité relative a été mis en place sur un ensemble de parcelles dans un réseau de haies brise-vent. Les mesures ont été réalisées sur 6 parcelles durant 42 nuits gélives entre 1998 et 2002. En situation de gel printanier, le pourcentage de bourgeons gelés a été cartographié pour repérer l'extension spatiale de cet aléa en tenant compte de l'état phénologique des arbres fruitiers. En situation radiative (ciel clair, vent inférieur à 3 m/s), lorsque la haie brise-vent ne bloque pas les écoulements nocturnes, le secteur le plus froid correspond au milieu de la parcelle alors que, quand la haie est quasi imperméable aux écoulements nocturnes superficiels, le plus fort refroidissement se produit en amont de la haie (blocage de l'air froid). En situation froide d'origine advective (autres situations), les résultats montrent que le secteur le plus froid est celui abrité par la haie.

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