Mechanical and Civil Engineering Seminar

Bubbly flows, liquid-gas flows in which the gas phase is dispersed into single bubbles, are commonly observed in many natural and industrial processes. One of the interesting features of such flows is that the fluid fluctuations can be very large. Turbulent-like fluctuations can be achieved for relatively small Reynolds numbers. As a result, bubbly flows are attractive for applications where mixing rates are needed but large shear rates are undesirable, as in the case of bioreactors. Over the last decade, we have been investigating different aspects of these flows with the objective to understand the nature of this pseudo-turbulent state. In this talk I will present a summary of our findings, including the study of zig-zagging instabilities in single bubbles and the not-so-easy task of measuring liquid fluctuations in dense bubble ensembles. In particular, I will discuss the differences and similarities between the fluid velocity spectra of ordinary and pseudo turbulence. At the end, I will show some preliminary results of a current project called bubbles with friends.