Development and validation of a 3D CFD model of drift and its application to air-assisted orchard sprayers

This work presents a three-dimensional (3D) computational fluid dynamics (CFD) model of spray drift from orchard sprayers that considers tree architecture, canopy wind flow and the movement of the sprayer to calculate sedimenting and airborne drift; thus tackling the challenges listed above. The model was validated against drift measurements from an apple orchard with different nozzles arrangements. The model was then used to evaluate the effect of drift reducing nozzles and fan airspeed on drift. The model predicted that drift reducing nozzles reduced the drifting distance by 50%, but increased near-tree ground deposition. This increase in ground deposition can be avoided whilst retaining the reduction in the drifting distance, by using a combination of drift reducing and standard nozzles. A reduced sprayer airflow can further reduce drift.