The impact of liquid drops on purple cabbage leaves (Brassica oleracea l. Var. Capitata)

Liquid drop impact on solid surfaces has been well studied due to its wide industrial application; however, there are very few studies of liquid drop impact on vegetable surfaces. The present work determined the drop impact pattern on purple cabbage leaves' surface and evaluated the influence of water drop viscosity and surface tension. The pattern of fluid impact on cabbage surface was evaluated by using a high-speed camera (1250 frames/s) at different impact heights for Weber numbers ranging from 100-800. The results showed that greater maximum spread factor was achieved with higher impact speed and lower surface tension drops. Viscosity had great influence on maximum spread factor and on dynamic impact. Maximum scaled spread factor xi(max) was We(1/4) for low viscosity water drops (water and Tween20-water). Fluid viscosity could be increased or surface tension decreased to prevent droplet rebound and keep them on purple cabbage surface by spraying them with an edible coating.