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The interaction of a bubble with an immersed horizontal solid surface is studied experimentally. The effect of presence of a surfactant (limited to a specific nonionic surfactant,˛-terpineol, of various concentrations) and of surface material (cleaned glass, polypropylene, polyethylene, and Teflon) is investigated. The study focuses on two particular stages of the interaction, (i) the process of bubble bounce, which includes a collision and subsequent rebound from the solid surface, and (ii) the bubble attachment, which occurs after collision in time much longer than the duration of bounce and also after disappearance of all visible bubble movement. It is observed that the effect of the surface material on the bouncing is minor, possibly due to the liquid film separating the bubble and the solid surface. The presence of surfactant significantly affects the bouncing process. It not only decreases the initial bubble velocity, but also diminishes the bubble deformation after the collision and suppresses the bubble rebound from the surface. No rebound from the surface is observed in the most concentrated (1 × 10 −3 mol/L)˛-terpineol solution. The adhesion time depends both on the solid material and˛-terpineol concentration. If the˛-terpineol concentration is increased, the adhesion time increases in the case of polypropylene surface, while it decreases in the case of polyethylene and Teflon surfaces. Results of this study are relevant for the description of attachment mechanism and to determine the proper conditions for selective flotation of plastics.L'interaction d'une bulle avec une surface pleine horizontale immergée estétudiée expérimentalement. L'effet de la présence d'un agent tensioactif (limitéà un agent tensio-actif nonionique spécifique, le˛-terpinéol, de diverses concentrations) et de matériau de surface (verre nettoyé, polypropylène, polyéthylène et Téflon) estétudié. L'étude se concentre sur deuxétapes particulières de l'interaction, (i) le processus de rebondissement de la bulle, incluant une collision et un rebondissement subséquent de la surface pleine, et (ii) l'adhérence de la bulle, qui se produit après la collision, d'une durée plus longue que la durée du rebondissement, etégalement, après la disparition de tout mouvement visible de la bulle. Il est observé que l'effet du matériau de surface sur le rebondissement est mineur, probablement dûà la pellicule liquide séparant la bulle et la surface pleine. La présence de l'agent tensio-actif affecte de manière significative le processus de rebondissement. Elle diminue nonseulement la vitesse initiale de la bulle, mais diminueégalement la déformation de la bulle après la collision et supprime le rebondissement de la bulle de la surface. Aucun rebondissement de la surface n'est observé dans la solution la plus concentrée de˛-terpinéol (1 × 10 −3 mol/L). La durée d'adhérence dépend aussi bien de la concentration du matériau solide que de la concentration en˛-terpinéol. Si la concentration en˛-terpinéol est augmentée, la durée d'adhérence augmente dans le...

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Shape oscillations of a spherical bubble or drop, for which part of its interface is fixed due to contact with a solid support, are studied analytically using variational methods. Linear oscillations and irrotational flow are assumed. The present analysis is parallel to those of Strani and Sabetta [“Free vibrations of a drop in partial contact with a solid support,” J. Fluid Mech. 141, 233–247 (1984)]10.1017/S0022112084000811; and Bostwick and Steen [“Capillary oscillations of a constrained liquid drop,” Phys. Fluids 21, 032108 (2009)]10.1063/1.3103344 but is also able to determine the response of bubbles or drops to movements imposed on their supports or to variations of their volumes. The analysis leads to equations of motion with a simple structure, from which the eigenmodes and frequency response to periodic forcing are easily determined.

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