Welcome to the next PoreLab lecture!
Who: Professor Eirik G. Flekkøy, PoreLab UiO, Njord center, Department of Physics, University of Oslo
When: Wednesday 25 October at 13:00 (Oslo time)
Where: Kelvin room (PoreLab Oslo), the lecture will be streamed live to the common room (PoreLab Trondheim). From anywhere else, you will be able to participate via the following Zoom link:
Title: Cavitation dynamics in creeping flow
Cavitation is a ubiquitous and sometimes destructive, phenomenon. For instance, cavitation bubbles may interrupt water flow in plants or severely damage the surfaces of machines such as pumps and propellers. The so-called tribonucleation of vapor bubbles has been proposed to be responsible for the cracking sound produced by the manipulation of human synovial joints. To study cavitation up close we have developed an experimental setup where a sphere in water abruptly leaves a flat surface starting from a separation of only 10 nm.
Upon upward movement of the spherical surface, a cavitation bubble forms and develops branched fingers through the Saffmann-Taylor instability. Simultaneously, negative liquid pressures in the range of ∼10atm are observed. These large tension values occasionally lead to secondary nucleation events. The bubble sizes satisfy a predicted Familiy-Vicsek scaling law where the bubble area is proportional to the inverse bubble lifetime. The fact that creeping flow cavitation bubbles are more short lived the larger they are separate them from bubbles that are governed by inertial dynamics