CFD models as a tool to analyze the deformation behavior of grape leaves under an air-assisted sprayer

The air-assisted sprayer can effectively promote the deformation of tree leaves and improve the deposition performance of droplets in the target canopy interior with the help of strong assisted airflow. This study selected the grape leaves as the research object to clarify the deformation behavior of leaves under the assisted airflow. Firstly, a bidirectional fluid-structure interaction model was established using computational fluid dynamics (CFD) based on the measurement of leaves parameters. The model was verified by a high-speed camera, and the maximum deformation of leaves centroid and tip in CFD simulation were compared with the shooting results. The maximum relative error was 8.73%, which shows that the model can accurately simulate the deformation of the grape leaves. Secondly, a universal rotation center combination simulation was carried out by taking the airflow velocity (v), airflow angle (alpha), leaf inclination angle (beta), and stalk leaf angle (gamma) as experimental factors. The regression analysis shows that the mean absolute percentage error (MAPE) of leaves centroid and tip regression equations was 2.12% and 2.57%, and the coefficient of determination (R-2) was 0.9578 and 0.9607, respectively. Further, the MAPE between the theoretical and simulated values of the change of leaf inclination angle was 2.53%, and R-2 was 0.9619. The maximum relative error between the theoretical and actual values was 11.46%, indicating that the method proposed in this paper is accurate to some extent in predicting the leaf inclination angle. Finally, this paper analyzed the variation of the windward area of grape leaves and emphasized the necessity of applying appropriate assisted airflow according to the leaf growth characteristics. The research results of this paper can provide a reference for the regulation and optimization of the pneumatic system of sprayers.