Pattern selection in radial displacements of a confined aging viscoelastic fluid
| When |
May 03, 2022
from 11:30 to 12:00 |
|---|---|
| Where | Salle des thèses |
| Attendees |
Palak |
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Intricate fluid displacement patterns, arising from the unstable growth of interfacial perturbations, can be driven by fluid viscoelasticity and surface tension. In my talk, I will highlight various experimental approaches that we have used to control interfacial instabilities between a Newtonian and an aging viscoelastic fluid. A soft glassy suspension ages, i.e. its mechanical moduli evolve with time, due to the spontaneous formation of suspension microstructures. I will discuss how the shear and time-dependent rheology of an aging suspension can be exploited to generate a wide variety of interfacial patterns during its displacement by a Newtonian fluid. I will show a rich array of interfacial pattern morphologies: dense viscous, dendritic, viscoelastic fracture, flower-shaped, jagged, that are formed due to the miscible and immiscible displacements of an aging colloidal clay suspension by Newtonian fluids injected into a radial quasi-two-dimensional geometry. I will show how we can generate the same sequence of pattern morphologies by appropriately changing the displacing fluid flow rate, while keeping the age of the displaced suspension fixed. Finally, I will present a new parameter, the areal ratio, which we can employ to uniquely identify and segregate the observed pattern morphologies in a three-dimensional phase diagram spanned by the suspension aging time, the displacing fluid flow rate, and interfacial tension. Besides being of fundamental interest, our results are useful in predicting and controlling the growth of interfaces during fluid displacements.