Behavior analysis of spray droplet interacting with plant leaves based on virtual model

Abstract: More scholars in recent years have interest in studying the interaction between spray droplets and leaves. However, due to limitations on the computational efficiency of the computer, the physical-based approaches to simulate the processes cannot meet the requirements on both rendering efficiency and considering physical laws at the same time. Aiming at the limitation of traditional simulation on interactions between droplets and leaves, which can only be applied to horizontal leaves, an experiment-based simulation method on interactions between droplets and any leaves, together with a new algorithm on bounce direction of droplets was proposed in this study in order to improve the situation of overly cost calculation time yet poor on accuracy on fluid mechanics of the popular spray models used currently. The interaction between droplets and leaves was simulated based on the experimental results in this paper by combining the improved algorithms based on the predecessors of existing formulas. As the first step, the macro-high-speed camera was used to monitor droplet on the leaf at different angles among 0°~50° of inclination, and measure its static contact angle size. Then the pattern of changes on the static contact angle of the droplet was fitted when the leaf inclination angle was increasing, and generalizing the existing bounce judgment formula to any inclined leaf. Finally, the Monte Carlo method was introduced to calculate the direction of droplet bounce. Instead of using the original specular reflection, the direction of droplet bounce was not in accordance with a single track to run, but turbulent as a sector, making it more consistent with the real environment. The simulation in this study was carried out on the platform of Windows8 Operating System, and using OpenGL to simulate the interaction between droplets and leaves. Simulation results showed that this method can reflect the physical law of collision, bounce judgment, dwell and splash of droplet with any inclined leaf. Besides, simulation in this study prevented the abuse of computational work load caused by the fluid mechanics formulas, and furthermore, the Monte Carlo perturbation was used instead of specular reflection ,making the simulation process in the calculation relatively small while at the same time being more in line with the actual physical laws. This study provides a new way to look into the interaction between droplets and leaves, supporting the calculation on the deposition amount of plant canopy interacting with a large number of droplets, and also possibilities for real-time rendering of large-scale plant scene and fog field interaction.