Berkeley Fluids Seminar

University of California, Berkeley

Bring your lunch and enjoy learning about fluids!

3110 Etcheverry Hall, 12:00-13:00

Monday, May 8, 2017

Vineeth (Vinny) Chandran Suja (Stanford)

Bubbles on Capillaries: (I) The bubble shape hysteresis (II) Single bubble coalescence experiments for developing foam resistant lubricants

Abstract: Bubbles supported on capillaries submerged in liquids are often used as part of experimental setups for conducting interfacial rheology measurements and coalescence experiments. One such system is the recently developed Dynamic Fluid-Film Interferometer (DFI) in which bubbles supported on capillaries are used to perform single bubble coalescence experiments. The first part of the talk focuses on a new phenomenon discovered during the initial design of the DFI – a bifurcation in the equilibrium states of bubbles expanding and contracting on capillaries. This bifurcation is a consequence of gas compressibility and results in a hysteretic phenomenon, which we have termed as the bubble shape hysteresis. Understanding bubble shape hysteresis is crucial to applications requiring precise control over the size of bubbles formed on capillaries. The second part of the talk focuses on DFI experiments aimed at developing foam resistant lubricants. Foam stability tests on oils from the four common base oil groups (as defined by the American Petroleum Institute) indicate that Group I and IV oils are the most and least prone to foaming, respectively. Reconstructed film profiles during thin film drainage leading up coalescence show that solutocapillary Marangoni flows are responsible for the foam stabilization in lubricant base oils.

Biography: Vineeth (Vinny) Chandran Suja is a doctoral student with Prof. Gerry Fuller at Stanford working on the interfacial rheology and fluid mechanics of non-aqueous and complex fluids. Prior to joining Stanford, he obtained a Master’s Degree in Mechanics (Ecole Polytechnique, Paris) and in Aerospace Engineering (Indian Institute of Science), and a Bachelor’s degree in Mechanical Engineering (College of Engineering, Trivandrum).

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