Dynamic behaviors of fertilizer droplets impacting tea leaf surfaces

Abstract

With the emergence of dissolved organic fertilizers and new foliar fertilizers, the adoption of fertigation via sprinkler systems has become increasingly prevalent in tea cultivation across various provinces in China. However, extensive water and fertilizer management practices have hindered the enhancement of tea yield, quality, and economic benefits. The appropriate management mode is based on maximizing spray retention, which is significantly influenced by the impingement dynamics of fertilizer droplets on tea leaves. Nonetheless, research in this area is still relatively limited. In this study, the dynamic behaviors of fertilizer droplets impacting tea leaf surfaces (Wu-Niuzao) are explored through both experiments and a Coupled Level Set and Volume of Fluid (CLSVOF) interface-capturing method. The effects of Weber number and inclination angle α on droplet impact dynamics, including impact phenomenology, maximum spreading diameter, maximum spreading time and the associated principles, are thoroughly explored. The simulation predictions provide a well match with the experiment results, suggesting that the CLSVOF interface tracking approach can offer theoretical support for enhancing fertilization efficiency. Three distinct impact behaviors (deposition, receding breakup, and sliding-off) were systematically identified across ranges of Weber numbers and α values, which significantly influence the dynamics of drop impact. The findings indicate that as Weber number and α increase, the tangential component (We_T) and gravity forces are strengthened to promote the later droplet spread, result in additional droplet spreading, and lead to rivulet formation. The established quantitative relationships and corresponding results can assist in the rational selection and design parameters of sprinkler irrigation systems, providing valuable insights for enhancing fertilization efficiency in tea plantations in China.