Simulating spray droplet impaction outcomes: comparison with experimental data

Abstract

BACKGROUND A suite of plant retention spray models has been developed to simulate spray retention using virtual surfaces (either single leaves or whole plants) and their outputs compared with experimental data for the equivalent spray scenarios. RESULTS The results for a single formulation (0.1% v/v lecithin mixture in water) and difficult to wet plant species Chenopodium album L (common lambsquarters) are presented. They include experimental observations with single leaves, as well as simulations of virtual impaction events, conducted to provide for the first time estimates of f (the proportion of theoretical impact drop diameter at shatter). With this factor prescribed, multi‐plant simulations using a range of nozzle types and droplet sizes (volume mean diameter (VMD) range 241 to 530 μm) are compared with equivalent experimentally determined spray retention by real plants. The simulations demonstrated that impaction resulted predominantly in shatter with the production of daughter droplets, and that retention is mainly due to re‐capture of these droplets. Overall the simulations show the same trends as experimental retention results from different nozzle applications, but at best predicted retention results were 68% to 79% of experimental percentage retention, depending on plant spacing. CONCLUSIONS Retention is the result of some primary drop capture but predominantly by recapture of shatter droplets as the modelling illustrates. The value of f affects the droplet shatter outcome and can result in fewer, more energetic daughter droplets, or more droplets but with lower energies. However, this effect alone cannot explain the discrepancy between actual and simulated results. Possible operational influences are discussed. © 2020 Society of Chemical Industry

Evaporating droplets on inclined plant leaves and synthetic surfaces: Experiments and mathematical models

“…As the droplet coverage area is the largest with 1% S465 on wheat of all our results, hence covering more stomata, the effect of stomata may need to be included in a future evaporation model. We close this section by noting that the authors are working on a larger project aiming to build interactive software for simulating agrochemical spraying of crops [61,62]. In terms of future research, it would be useful to incorporate information from the present study into this software.…”

Implicit reconstructions of thin leaf surfaces from large, noisy point clouds

“…Going forward, the plant surfaces reconstructed by this method will be incorporated into forthcoming models for droplet spreading and movement on leaves. They will also be added to the growing suite of plant models available in a 'plant retention spray model' (PRSm) [2,3,4]. There they will be used to simulate interception, shatter, bounce and retention of droplets on plant crops with an outlook towards developing more efficient agrichemical spraying processes.…”

“…Surface reconstruction is the problem of constructing a digital representation of a physical object from scanned data. Techniques for reconstructing a surface with global smoothness are of specific interest in our related work on simulating droplet retention on plant surfaces [1,2,3,4,5]. Many algorithms have been proposed for this type of reconstruction from point cloud datasets [6,7,8,9,10,11,12].…”

Image analysis of shatter and pinning events on hard‐to‐wet leaf surfaces by drops containing surfactant

“…2 As the processes are better understood, they can be incorporated in new software to simulate agrichemical spraying of plants that will be reliable from a scientific perspective. [3][4][5] This paper focuses on physical mechanisms that influence retention of spray drops on leaf surfaces. In particular, high-speed photography is used to develop a new methodology and approach to better understand bounce and shatter events.…”