Bubbles in yield stress fluids: rheological trapping, flow onset and motion

Abstract: Bubbles abound in yield stress suspensions, pastes and gels, occurring either as a designed part of a process/product, or as an unwanted feature. The interest in such flows is both fundamental and industrial, with the latter coming in particular from concerns surrounding emissions from oilsands tailings ponds. We present theoretical, computational and experimental results from our recent work on characterizing flow onset of bubbles as they grow. We then explore various complications relevant to the tailings pond setting. We show that when multiple bubbles (bubble clouds) exceed a critical volume fraction, a “burst” release can occur. We outline the effects of sequential bubble release, providing damaged pathways along which successive bubbles travel or are attracted towards. Finally we look at the effects of large yield stress, which leads to highly irregular static bubbles trapped.

Bio: Ian Frigaard is Professor of Mechanical Engineering and Applied Mathematics at UBC, since 2000, following an industrial career with Schlumberger, postdoctoral research at the University of Linz and graduate degrees at University of Oxford. He leads a group of 15 researchers that studies rheology, non-Newtonian fluid mechanics and industrial processes that address sustainability issues in the oil and gas industry. This includes a long-standing and ongoing activity on well leakage/integrity and cementing, and newer research on gas release from oil sands tailings ponds. His research has been recognized by the award of the Killam Research Prize (UBC), the CAIMS Industrial Mathematics Prize, the Society of Petroleum Engineers Drilling Engineering Award, the Stanley Mason Award of the Canadian Society of Rheology, the Canadian Society of Mechanical Engineers Fluid Mechanics Medal and the British Society of Rheology Annual Award. He is editor of the Journal of non-Newtonian Fluid Mechanics.