A new integrated CFD modelling approach towards air-assisted orchard spraying. Part I. Model development and effect of wind speed and direction on sprayer airflow

Endalew, Ayenew Melese; Debaer, C.; Rutten, N.; Vercammen, J.; Delele, Mulugeta Admasu; Ramón, Herman; Nicolaı̈, Bart; Verboven, Pieter

doi:10.1016/j.compag.2009.11.005

Cited by 62 publications

(29 citation statements)

References 27 publications

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“…wake turbulence by short-circuiting the eddy cascade, which in turn due to its smaller length scales compared to shear turbulence is subjected to faster dissipation so that vegetation can act as a net sink for turbulence kinetic energy (e.g. Endalew et al, 2010Endalew et al, , 2009Green, 1992;Green et al, 1995;Wilson and Shaw, 1977).…”

Section: Numerical Settings and Vegetation Modelmentioning

confidence: 99%

Influence of avenue-trees on air quality at the urban neighborhood scale. Part I: Quality assurance studies and turbulent Schmidt number analysis for RANS CFD simulations

Gromke¹,

Blocken²

2015

Environmental Pollution

136

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Flow and dispersion of traffic pollutants in a generic urban neighborhood with avenue-trees were investigated with Computational Fluid Dynamics (CFD). In Part I of this two-part contribution, quality assessment and assurance for CFD simulations in urban and vegetation configurations were addressed,before in Part II flow and dispersion in a generic urban neighborhood with multiple layouts of avenue trees were studied. In a first step, a grid sensitivity study was performed that inferred that a cell count of 20 per building height and 12 per canyon width is sufficient for reasonable grid insensitive solutions. Next, the performance of the realizable k-ε turbulence model in simulating urban flows and of the applied vegetation model in simulating flow and turbulence in trees was validated. Finally, based on simulations of street canyons with and without avenue-trees, an appropriate turbulent Schmidt number or modeling dispersion in the urban neighborhood was determined as Sc(t) =0.5.

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Section: Numerical Settings and Vegetation Modelmentioning

confidence: 99%

Influence of avenue-trees on air quality at the urban neighborhood scale. Part I: Quality assurance studies and turbulent Schmidt number analysis for RANS CFD simulations

Gromke¹,

Blocken²

2015

Environmental Pollution

136

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“…Measurements relating to these three sets of posts were taken at 30 cm intervals, starting from a height of 30 cm above the ground and continuing to a height of 3.0 m and then at 50 cm intervals up to a maximum height of 4.5 m. Additional horizontal posts (labelled B), positioned at a height of 1.8 m, were used to take measurements at 20 cm intervals from the centre of the fan to the position corresponding to post A. Measurements were taken at a total of 201 different points (67 points per plane, in three planes). In similar studies, only one side of the sprayer was considered (Da Silva et al, 2006;Endalew et al, 2010aEndalew et al, ,b, 2011Endalew et al, , 2012Duga et al, 2013), although it is well known that air distribution of axial fans is asymmetric. This as- …”

Section: Methodsmentioning

confidence: 99%

Description of the airflow produced by an air-assisted sprayer during pesticide applications to citrus

Salcedo¹,

Garcerá²,

Granell³

et al. 2015

Span. j. agric. res.

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Atmospheric drift of plant protection products is considered a major source of air pollution during pesticide applications. Citrus protection against pests and diseases usually requires application of these products using air-blast sprayers. Many authors have emphasized the influence of vegetation on the risk of spray drift. The aim of this work was to describe in detail how the airflow from an air-blast sprayer behaves when it reaches citrus trees and, in particular, the effect that the tree canopy has on this flow. Tests were conducted at a commercial citrus orchard with conventional machinery, placed parallel to a row of trees. Air velocity and direction was measured using a 3D ultrasonic anemometer in 225 points situated in three parallel planes perpendicular to the equipment. The stability of the airflow at each measuring point was studied and the mean velocities were graphically represented. Two vortexes, one behind the canopy, and another over the tree, have been deducted and never been reported before. Both may have an important influence on the trajectories of the sprayed droplets and, as a consequence, on the way in which plant protection products are diffused into the atmosphere. Observed turbulence intensities were higher than in similar experiments conducted in other tree crops, which may be attributable to the higher air volume generated by the machinery used for citrus protection and to the higher foliage density of citrus orchards.

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“…Considering the effect of a leafless canopy, this inverse-linear decay of the moving sprayer air-jet started to change at about x/D > 20 (Endalew et al 2010a), due to the fact that the presence of the canopy induced the jet velocity magnitude to decay faster within and behind the canopy. Furthermore, considering the presence of leaves, the jet velocity magnitude started decaying earlier (at about x/D = 10) and faster.…”

Section: Sprayer Jet Velocity Decaymentioning

confidence: 97%

“…Measurement of air velocity magnitude from the three sprayers was conducted in an experimental orchard (pcfruit, Sint-Truiden, Belgium) in spring 2008 (Endalew et al 2010a) when all the trees were still leafless and in summer 2008 when the trees were fully-leafed. The experimental site was characterized by several plots dominated by even-aged north-south oriented rows of pear and apple stands on a flat land feature (Fig.…”

Section: Experimental Site and Measurementsmentioning

confidence: 99%

Modelling the Effect of Tree Foliage on Sprayer Airflow in Orchards

Endalew

Debaer²,

Rutten³

et al. 2010

Boundary-Layer Meteorol

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The effect of tree foliage on sprayer airflow through pear trees in a fruit orchard was studied and modelled in detail. A new three-dimensional (3-D) computational fluid dynamics model that integrates the 3-D canopy architecture with a local closure model to simulate the effect of the stem and branches and leaves of trees separately on airflow was developed. The model was validated with field observations made in an experimental orchard (pcfruit, Sint-Truiden, Belgium) in spring and summer 2008 and was used to investigate the airflow from three air-assisted orchard sprayers (Condor V, Duoprop and AirJet quatt). Velocity magnitudes were measured before and behind leafless and fully-leafed pear canopies across the row while the operating sprayers are passing along the row, and were compared with the simulations. The simulation results predicted the measured values well with all the local relative errors within 20%. The effect of foliar density on airflow from the three air assisted sprayers was manifested by changing the magnitude and direction of the sprayers' air velocity behind the canopy, especially at the denser regions of the canopy and by changing the pattern of velocity decay horizontally along the jet. The developed methodology will also allow a thorough investigation of atmospheric airflow in canopy structures.

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A new integrated CFD modelling approach towards air-assisted orchard spraying. Part I. Model development and effect of wind speed and direction on sprayer airflow

Cited by 62 publications

References 27 publications

Influence of avenue-trees on air quality at the urban neighborhood scale. Part I: Quality assurance studies and turbulent Schmidt number analysis for RANS CFD simulations

Influence of avenue-trees on air quality at the urban neighborhood scale. Part I: Quality assurance studies and turbulent Schmidt number analysis for RANS CFD simulations

Description of the airflow produced by an air-assisted sprayer during pesticide applications to citrus

Modelling the Effect of Tree Foliage on Sprayer Airflow in Orchards

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