Damping Time of Bubble Oscillations in Clean Liquids and in Surfactants

0341645 - ÚCHP 2011 RIV DE eng C - Conference Paper (international conference)
Vejražka, Jiří - Vobecká, Lucie - Zedníková, Mária - Orvalho, Sandra - Tihon, Jaroslav
Damping Time of Bubble Oscillations in Clean Liquids and in Surfactants.
Fortschritt-berichte VDI, Reihe 3, Nr. 920. Düsseldorf: VDI Verlag, 2011 - (Schindler, F.), s. 47-60. ISBN 978-3-18-392003-7. ISSN 0178-9503.
[International Berlin Workshop on Transport Phenomena with Moving Boundaries /5./. Berlin (DE), 08.10.2009-09.10.2009]
R&D Projects: GA ČR GA104/08/0428; GA AV ČR(CZ) IAA200720801
Institutional research plan: CEZ:AV0Z40720504
Keywords : bubble shape oscillation * surface active agent * interfacial viscosity
Subject RIV: CI - Industrial Chemistry, Chemical Engineering

Shape oscillations of bubbles in surfactant solutions are investigated by means of high-speed imaging. Two cases are studied: bubbles attached to a capillary tip, and bubbles freely rising after detachment. The frequency f and the decay time tau of shape oscillations are evaluated, and their dependence on the surfactant concentration and on the bubble size is investigated. If the surfactant is present, tau shortens and a minimum is found for a certain concentration. This observation demonstrates that in the surfactant solutions, the energy dissipation linked to interfacial effects can be much more important than the dissipation due to liquid viscosity. The frequency f increases with increasing concentration of the surfactant first, and then it drops rapidly at concentration, at which tau is minimal. The initial increase of the oscillation frequency suggests that the interfacial elasticity can play an important role in surfactant solutions.
Permanent Link: http://hdl.handle.net/11104/0184564