Computational fluid dynamics analysis of an agricultural spray in a crossflow

Abstract

Spraying is the most widely used method for pesticide application and the resulting spray drift has become a major concern. Reliable spray simulations can help to better understand this phenomenon and evaluate methods to prevent it. This paper proposes a methodology to set up a computational fluid dynamics simulation of sprays. A number of benchmark flows were studied to assess the accuracy of the proposed method. The simulation of a jet in a crossflow was able to capture counter-rotating vortex pairs and the predicted trajectory agreed with experimental data. A multiple-injector technique is then used to replicate the velocity distribution of sprays without modelling the liquid sheet breakup. Spray simulations were able to capture air entrainment and predicted a realistic droplet distribution pattern. The volume of droplets deposited on the collector lines in drift simulations was in good agreement with experimental data in the near field. As the droplets moved further downstream, however, a deviation between the simulation results and experimental data was observed. The drift simulation results indicated that in a wind speed of 2ms−1, droplets of diameter <75μm are prone to drift.