Dynamic simulation of fluid-structure interactions between leaves and airflow during air-assisted spraying: A case study of cotton

The airflow of air-assisted spraying can widen droplet transport channel, increase the variable-track motion of droplets, and uniform of droplet deposition in canopy. However, it is still a challenge to analyze the dynamic interaction behavior between leaves and airflow at the canopy leaves scale. Based on Finite Element (FE) and Lattice-Boltzmann (LB) solver, a two-way, Fluid-Structure Interaction method was proposed to analyze the aerodynamics of leaves under airflow and flow field distribution in the canopy. First, a virtual, simplified 3D cotton plant was generated based on morphology and growth law. Furthermore, a two-way, Fluid-Structure Interaction model was established by co-simulations with the structurally explicit FE solver and LB solver. Finally, the accuracy of the numerical simulations was verified by indoor experiment tests from the two aspects of fluid domain and solid domain. The verification results in the fluid domain showed that mean absolute error of prediction (MAEP) and normalized mean absolute error (NMAE) between simulated and measured values were 0.6317 and 11.38%, respectively. The solid domain verification showed that the maximum value of NMAE between simulated and experimental changes of leaf inclination angle were 21.46%, indicating that the numerical model can accurately simulate the deformation of the cotton leaves. The leaves in flow field reached dynamic stability after 0.4s when the airflow with speed 10 m/s blowing to the canopy. The simulation results can be used to optimize the operating parameters before air-assisted spraying.