Prof. Ranjini Bandyopadhyay - lecture 11 September 2024

Title: Distinct morphologies and growth kinetics of interfacial patterns formed by the radial displacement of an aging viscoelastic suspension
Speaker: Prof. Ranjini Bandyopadhyay
Affiliation: Raman Research Institute, Bengaluru, India
Abstract: When a soft glassy colloidal suspension is displaced by a Newtonian fluid in a radial Hele-Shaw geometry, the pattern morphology that develops at the interface is determined by the complex rheology of the former. I shall show here that a range of pattern morphologies characterised by distinctive structural features can be formed by controlling the elasticity of the displaced suspension, the flow rate of the displacing fluid and the interfacial tension of the fluid pair. Interestingly, all the different morphological features can be distinguished in terms of their areal ratios, defined as the ratio of the areas occupied by the fully-developed pattern and the smallest circle enclosing it. I shall discuss how a systematic study of the spatio-temporal pattern growth can reveal important information about pattern selection mechanisms. The analysis of the time-evolution of the patterns reveal interesting correlations between their growth mechanisms and fully-developed morphologies. Such systematic identification of the unique temporal features characterising pattern growth at the interface between an aging viscoelastic clay suspension and a Newtonian fluid may be useful in pre-empting and suppressing the onset and evolution of interfacial instabilities in the displacement of mud and cement slurries