Droplet deposition of agrochemical spraying: Comparison of results from a random-walk model and CFD simulations

RENAUDO, CARLOS A.; BUCALÁ, VERÓNICA; BERTIN, DIEGO E.

Canadian Journal of Chemical Engineering

John Wiley and Sons Inc

Año: 2024 p. 1 - 13

The effectiveness of agricultural spraying processes depends considerably onthe ability of the atomized droplets to reach the target site in the desiredamount. In this work, two mathematical models to study the trajectories anddeposition of atomized droplets are implemented and compared. On the onehand, a computational fluid dynamics (CFD) coupled with discrete phasemodel (DPM) is implemented to calculate the trajectories of atomized dropletsand determine distances at which the droplets are deposited. The continuousphase (atmospheric air) is modelled by continuity, momentum, and energyequations. On the other hand, a Lagrangian random-walk (LRW) model basedon force and energy balances to predict the pulverization process of a nozzle isformulated and implemented in Python. Both models take into account theeffects of drag, gravity, buoyancy, and evaporation on individual droplets, aswell as the impact of atmospheric stability and dispersion. By tracking a largenumber of trajectories, meaningful estimates of dispersal statistics can beobtained. The LRW model accurately replicated the trajectories, deposition distances,and final diameters of atomized droplets for three atmospheric stabilitycases, compared with CFD simulation results. The results of both modelsagreed that 100 μm droplets were most susceptible to wind-induced spray drift,depositing at the furthest distances from the nozzle. In addition, 50 μm dropletsexhibited a significant tendency to evaporate entirely before reaching theground. The LRW model is found to be a cost-effective alternative for estimatingspray drift compared to the computationally intensive CFD approach.