Proto-rheological flows of yield-stress fluids

Abstract: The measurement of rheological properties from non-idealised flows known as proto-rheology, is routinely used to characterise yield-stress materials (YSMs) for which the use of a rheometer is not practical. The microstructure of YSMs gives rise to complex rheology including a yield stress that needs to be exceeded for the material to flow, shear-thinning, viscoelasticity and wall slip. Here, we explore two proto-rheological flows which can provide estimates of the yield stress: the “syringe test” and the vertical vibration of a sessile drop. We use direct comparison between experiments and numerical simulations of the time-dependent Cauchy equations coupled to the Saramito-Herschel-Bulkley (SHB) constitutive model to highlight fundamental challenges in simulating these flows in which yielded and unyielded material coexist.

Bio: Anne Juel is Professor of Physics of Fluids and Soft Matter at the University of Manchester and has been the Director of the Manchester Centre for Nonlinear Dynamics since 2014. Her research focuses on fluid-structure interaction and interfacial phenomena in complex fluids and soft matter including bubble dynamics, sedimentation, complex fluid rheology, soft suspensions and microfluidic biomimetic models. She is a Fellow of the American Physical Society and a former chair of APS DFD. She serves as an Associate Editor of JFM and sits on the editorial boards of Annual Reviews of Fluids Mechanics and PRSA.