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This work concerns the numerical prediction of pesticide deposits on vine by air assisted sprayers. This numerical model consists in two different parts: the air flow characteristics were obtained through a Navier-Stokes solver in which additional terms have been introduced in order to account for the modification of the flow by the vine foliage. The theoretical form of these terms was derived through an averaging procedure. As a result, the canopy effect was modelled by introducing momentum and turbulence source terms in the Navier-Stokes equations. The constants were identified thanks to experimental data obtained by direct measurements of the air flow speeds through an artificial canopy. The second part of the model consists in simulating the droplet cloud by means of a lagrangian stochastic model. The average motion of the droplets was computed through the use of lagrangian coordinates and the turbulence effect on the droplets was interpreted in term of statistical properties of the droplet cloud. The tractor displacements were accounted for through unsteady boundary conditions. Once the size and the droplets cloud locations have been determined, the deposit was predicted for a vine row of one meter length using an efficiency coefficient obtained from simulations. Thanks to this approach we were able to quantify the effect of air turbulence on droplet deposition / Ce travail concerne la prédiction numérique de dépôts dans la vigne de pesticides pulvérisés avec assistance d'air. Le modèle numérique comprend deux parties : les caractétistiques du flux d'air sont obtenues à partir de la résolution des équations de Navier-Stokes dans lesquelles des termes additionnels ont été introduits pour prendre en compte les modifications du flux dues au feuillage. L'effet de la végétation est modélisé en introduisant des termes source de quantité de mouvement et de turbulence dans les équations de Navier Stokes. Les constantes ont été identifiées grâce à des données expérimentales obtenues par des mesures directes des vitesses d'air dans une végétation artificielle. la deuxième partie du modèle représente le nuage de goutteletters à l'aide d'une représentation Lagrangienne stochastique. Le mouvement moyen des gouttes est calculé à partir de leurs coordonnées Lagrangiennes et l'effet de la turbulence est pris en compte dans les propriétés statistiques du nuage; Les déplacements du tracteur sont pris en compte par des conditions aux limites transitoires. Une fois que la taille et la position du nuage de gouttelettes est déterminé, le dépot est calculé sur un mètre de rang de vigne en utilisant un coefficient d'efficacité calculé à l'aide de simulations. Grâce à cette approche, on peut prédire les effets de la turbulence sur le dépôt des goutte

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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The quality of pesticide spraying depends on boom movement. A conveyor with a shaking platform was built to analyse the influence of boom movements on spray distribution. It is able to generate uniform translations and rotational movements of a small boom under laboratory conditions. The overall ground spray distributions were studied using image analysis. Suitable representations and mathematical tools were considered to analyse the unevenness of ground spray distributions and to compare accurately spray patterns. The effects of boom height, boom speed and nozzle type on dynamic spray distributions were analysed and compared with stationary distributions. The effects of yaw and roll movements were also considered. Measurements of droplet size and velocity made with a phase Doppler analyser were added to complete the dynamic effect study. Tests were repeatable but some fluctuations were obtained when boom height increased. Static and dynamic distributions Author-produced com -doi:10.1016/j.biosystemseng.2006.08.014 2 have the same overall unevenness but this unevenness is more important in dynamic conditions due to turbulence effects. Roll and yaw increase unevenness. For roll movements, changes in nozzle heights explain the variations. For yaw movements, over-dosed areas are observed where the nozzles have a small horizontal velocity.version of the article published in Biosystems Engineering, 96(1), 29-39. Original publication available at www.elsevier.

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