Experimental study of drop impacts and spreading on epicarps: Effect of fluid properties

• Published in: Journal of food engineering 2012-04, Vol.109 (3), p.430-437
• Main Authors: Andrade, R., Skurtys, O., Osorio, F.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Computational fluid dynamics; Drop impact; Fluid flow; Food engineering; Food industries; Foods; Fundamental and applied biological sciences. Psychology; General aspects; Impact tests; Liquids; Mathematical models; Spray; Spread factor; Spreading; Viscosity; Weber number
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2011.10.038

► Drop impact of liquids on solid is a very complex problem. ► Prediction of ξmax is needed in many spray applications. ► Drop impact behavior on banana and purple cabbage epicarps is detailed. ► Viscosity and surface properties of the epicarp have a great influence on dynamic of impact. ► A new model is proposed to describe ξmax as an function of Re and We. The fluid mechanic of liquid drop impacts on solid food plays an important role in food engineering, e.g. when a spray technology is used to apply a coating. In the present work, drop impact behavior on banana and purple cabbage epicarps using high speed camera was studied. Drop velocity was controlled by modifying the height from which drop was ejected. Weber number varied from 100 to 800, whereas Reynolds number ranged from 1000 to 12,500. Liquid drop viscosity and surface tension effects on drop impact behavior were evaluated and temporal evolution of both spreading and flattening factors are presented. Results show that viscosity and epicarp surface properties had great influence on impact dynamics. For low viscosity liquid drops (water and Tween 20–water), the maximum spread factor, ξmax, scaled with We0.25±0.02, whereas for viscous fluid (water–glycerol mixture) it scaled with We0.16±0.02. Finally, a new model was proposed to better fit the experimental data than the Roisman’s and Scheller’s models.