VIII International Symposium on Modelling in Fruit Research and Orchard Management vol:803 pages:97-104
Modelling2007 location:Einsiedeln - Waedenswil, Switzerland date:1-5 July 2007
Effectiveness of on-target pesticide deposition and drift problems are strongly related to a complex interaction of meteorological conditions (wind speed and direction), canopy architecture and sprayer parameters (design, calibration and operation). Such complex interaction is difficult and expensive to experimentally analyse, especially in bigger canopies like orchards. CFD (computational fluid dynamics) simulations of air and droplet flows contribute to the understanding of the underlying processes during orchard spraying. So far almost all flow models are mainly based on porous media approaches with apparent canopy properties to represent the vegetation, which need to be determined experimentally. This work combined previously validated models of airflow through 3D canopy structures and models of airflow from air-assisted orchard sprayers to investigate sprayer airflow through orchards. The canopy flow model used the real 3D structural tree geometry instead of the porous media formulation. Measurement of actual trees was used to represent and simulate the 3D geometry of trees that were then used for airflow computation in ANSYS-CFX. The effects of wind speed and direction on the sprays from a cross flow sprayer (BAB-Bamps, Sint-Truiden, Belgium) around and through the canopies were modelled using the Reynolds-averaged Navier-Stokes (RANS) equations. The vertical air velocity profiles of both the sprayer and atmosphere are inline with previous works in the area. The results also showed detailed flow behaviours within the canopies showing the effects of canopy elements on the flow. In addition to providing an approach to model the interaction between atmospheric and sprayer airflow within 3D orchard canopies, the work is a potential source of information for the design, calibration and operation of air-assisted sprayers to increase the efficiency of pesticide application for effective control and drift reduction.