The role of Laplace pressure in the maximal weight of pendant drops

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:606

Article

Lecacheux, Laure^1,2  Sadoudi, Abdelkrim²  Duri, Agnes²  Planchot, Veronique²  Ruiz, Thierry¹ 

[1] Univ Montpellier, Univ Avignon, Montpellier SupAgro, UMR QualiSud,CIRAD,Univ La Reunion, 15 Ave Charles Flahault, F-34093 Montpellier 5, France

[2] Univ Montpellier, UMR IATE INRAE 1208, Montpellier SupAgro, 2 Pl Pierre Viala, F-34060 Montpellier 1, France

关键词: Pendant drop;    Maximal drop weight;    Capillary force;    Laplace pressure;    Curvature;    Image analysis;   

DOI  :  10.1016/j.jcis.2021.08.047

来源: Elsevier

【 摘 要 】

Hypothesis: The value of the maximal weight of a pendant drop formed at the end of a syringe needle is lower than the intensity of the corresponding capillary force. The balance of the external forces applied to the maximal pendant drop must be completed by the overpressure generated by the piston of the syringe. Inside the drop, the Laplace pressure corresponds to this overpressure. Experiments: Pendant drops are made with three liquids and five different needle diameters. The influence of Laplace pressure on the maximal weight is experimentally highlighted by modulating the drop curvatures thanks to glass beads placed at the apex of the pendant drop. Their maximal weight and curvatures are measured by image analysis. Findings: Experiments confirm that the balance of external forces must be completed by the force acting on the syringe piston. The overpressure on the piston has an impact on the drops via the Laplace pressure. A master curve between the mean curvature and the maximal volume of the pendant drops is observed. This result allows to validate an expression of the maximal weight which integrates the Laplace pressure. This work contributes to a better understanding of the maximal pendant drop properties and beyond, of the capillary phenomenon. (c) 2021 Elsevier Inc. All rights reserved.

【 授权许可】

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