Using integrated 3D canopy architecture and porous media models for prediction of orchard pesticide applications

A computational fluid dynamics (CFD) model that integrates wind, airflow from air-assisted sprayers and 3D canopy architecture was developed to help understand their interactive effect on orchard pesticide spraying. In spring 2007 canopy architectural data (3D internode coordinate and diameter) of pear trees (Pyrus communis) was collected in an experimental orchard (PCfruit, Sint-Truiden, Belgium). The data were converted into 3D virtual geometries using the representation method. A porous subdomain was created around each part of the canopy elements to represent the coverage of the leaves. The effect of the entire canopy on air and particle flow from a cross flow orchard sprayer (BAB-Bamps, Sint-Truiden, Belgium) was modelled by integrating 3D canopy architecture and porous media models that involve momentum and kinetic energy losses. The flow of the continuous phase (air) was solved using Navier-Stokes equations and k-e turbulence model and the position of the discrete phase (water droplets) in the continuous phase was tracked using a Lagrangian particle tracking multiphase flow model in ANSYS-CFX-11.00 (ANSYS, Inc., Canonsburg, Pennsylvania, USA) in steady state conditions.