Simulating spray droplet impaction outcomes: comparison with experimental data

Area of Science:

• Agricultural Engineering
• Physical Chemistry
• Plant Sciences

Background:

• Developed plant retention spray models to simulate spray retention on virtual surfaces.
• Compared model outputs with experimental data for various spray scenarios.

Purpose of the Study:

• To estimate the proportion of theoretical impact drop diameter at shatter (f) for the first time.
• To compare multi-plant simulations with experimentally determined spray retention on real plants.

Main Methods:

• Used a single formulation (0.1% v/v lecithin in water) and Chenopodium album L (common lambsquarters).
• Conducted simulations of virtual impaction events and multi-plant scenarios with varying nozzle types and droplet sizes (VMD 241–530 μm).

Main Results:

• Simulations indicated that impaction predominantly caused shatter, producing daughter droplets.
• Plant retention was mainly due to the re-capture of these shattered droplets.
• Simulated retention trends matched experimental results, but predictions were 68%–79% of experimental values.

Conclusions:

• Spray retention results from primary drop capture and predominantly by recapture of shatter droplets.
• The factor 'f' influences droplet shatter outcomes, affecting daughter droplet energy and quantity.
• Discrepancies between simulated and actual results suggest possible operational influences requiring further investigation.