Ian Frigaard, University of British Columbia

Ian Frigaard is Professor of Mechanical Engineering and Applied Mathematics at the University of British Columbia, where he has been a faculty member since 2000. He leads a research group of »15 persons, working on a range of industrial problems involving a blend of theory, modelling, computation and lab-scale experiments. Since 2016 he has been editor-in-chief of the Journal of non-Newtonian Fluid Mechanics. He has served on editorial and advisory boards of 7 other scientific journals of good repute, 4 of these in executive capacity. He has been honoured by CAIMS/SCMAI by the award of the 2010 Industrial Mathematics Research prize; at UBC by the Killam Research prize 2019; by the Society of Rheology by award of a fellowship; by SPE by the 2020 drilling engineering award; by the Canadian Society of Rheology with the 2022 Stanley Mason Award; and most recently by the CSME/SCGM through the 2024 Fluid Mechanics Medal.

Viscoplastic fluids: from theory to application

Viscoplastic fluids abound: from food products through polymer gels to industrial and natural slurries. The key mechanical feature of such fluids is yield stress behaviour, i.e. a threshold deviatoric stress that must be exceeded in order for the fluids to deform and flow. The most simple models of these materials (Bingham and Herschel-Bulkley fluids), are a century old and in common usage. In this talk we explore some of the theoretical changes that arise in studying typical flows of these fluids, i.e. as a result of the yield stress. These range from unique and interesting flow features through to effects on the hydrodynamic stability of flows. In the second part of the talk we move from theory to application. The applications are of two types. (i) New and novel flows that can be achieved because of the yield stress. Examples are given. (ii) Industrial processes where the yield stress has a fundamental effect on the flow. For the latter we outline two long standing research areas of relevance to greenhouse gas emissions, where surprisingly the yield stress can either help or hinder.