A curvilinear thin film model is used to simulate the motionudof droplets on a virtual leaf surface, with a view to betterudunderstand the retention of agricultural sprays on plants. The governing model, adapted from Roy et al. (2002 J. Fluid Mech. 454, 235–261) with the addition of a disjoining pressure term, describes the gravity- and curvature driven flow of a small droplet on a complex substrate: a cotton leaf reconstructed from digitized scan data. Coalescence is the key mechanism behind spray coating of foliage, and our simulations demonstrate that various experimentally observed coalescence behaviours can be reproduced qualitatively. By varying the contact angle over the domain, we also demonstrate that the presence of a chemical defect can act as an obstacle to the droplet’s path, causing break-up. In simulations on the virtual leaf, it is found that the movement of a typical spray size droplet is driven almost exclusively by substrate curvature gradients. It is not until droplet mass is sufficiently increased via coalescence that gravity becomes the dominating force.
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机译:使用曲线薄膜模型来模拟虚拟叶表面上的运动 udof液滴,以更好地理解农业喷雾剂在植物上的保留。治理模型,改编自Roy等。 (2002 J. Fluid Mech。454,235-261)加上分离的压力项,描述了由重力和曲率驱动的小液滴在复杂基质上的流动:从数字化扫描数据重建的棉叶。聚结是叶片喷涂涂层背后的关键机制,我们的模拟表明,各种实验观察到的聚结行为可以定性地再现。通过改变区域上的接触角,我们还证明了化学缺陷的存在可能成为液滴路径的障碍,从而导致破裂。在虚拟叶片上的模拟中,发现典型的喷雾尺寸液滴的运动几乎完全由基质曲率梯度驱动。直到液滴的质量通过聚结充分增加,重力才成为主导力。
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