Interplay between viscosity and elasticity in freely expanding liquid sheets

Abstract

We investigate the dynamics of freely expanding liquid sheets prepared with fluids with different rheological properties, (i) viscous fluids with a zero-shear viscosity ${\eta }_0$ in the range $(1-1000)mPa.s$ and (ii) viscoelastic Maxwell fluids whose elastic modulus, $G_0$, characteristic relaxation time, $\tau$, and zero-shear viscosity, ${\eta }_0=G_0\tau$, can be tuned over several orders of magnitude. The sheets are produced by impacting a drop of fluid on a small cylindrical solid target. For viscoelastic fluids, we show that, when $\tau$ is shorter than the typical lifetime of the sheet ($\sim 10$ ms), the dynamics of the sheet is similar to that of Newtonian viscous liquids with equal zero-shear viscosity. In that case, for little viscous samples (${\eta }_0<\sim 30$ mPa.s), the maximal expansion of the sheet, $d_{\max }$, is independent of ${\eta }_0$, whereas for more viscous samples, $d_{\max }$ decreases as ${\eta }_0$ increases. We provide a simple model to account for the dependence of the maximal expansion of the sheet with the viscosity that is based on an energy balance between inertia, surface tension and viscous shear dissipation on the solid target, and which accounts well for our experimental data. By contrast, when $\tau$ is longer than the typical lifetime of the sheet, the behavior drastically differs. The sheet expansion is strongly enhanced as compared to that of viscous samples with comparable zero-shear viscosity, but is heterogeneous with the occurrence of cracks, revealing the elastic nature of the viscoelastic fluid.

10 pages, 9 figures

References in corpus (4)

• Percolation in a Model Transient Network: Rheology and Dynamic Light Scattering
• Fractures in complex fluids: the case of transient networks
• Free radially expanding liquid sheet in air: time- and space-resolved measurement of the thickness field
• Bursting of Dilute Emulsion-Based Liquid Sheets Driven by a Marangoni Effect

Cited by in corpus (4)

• Spreading and fragmentation of particle-laden liquid sheets
• Impact of beads and drops on a repellent solid surface: a unified description
• Competition between shear and biaxial extensional viscous dissipation in the expansion dynamics of Newtonian and rheo-thinning liquid sheets
• Instabilities in freely expanding sheets of associating viscoelastic fluids