Pinch-off of viscoelastic particulate suspensions
Thiévenaz, Virgile, Sauret, Alban
Abstract
The formation of drops of a complex fluid, for instance including dissolved\npolymers and/or solid particles, has practical implications in several\nindustrial and biophysical processes. In this Letter, we experimentally\ninvestigate the generation of drops of a viscoelastic suspension, made of\nnon-Brownian spherical particles dispersed in a dilute polymer solution. Using\nhigh-speed imaging, we characterize the different stages of the detachment. Our\nexperiments show that the particles primarily affect the initial Newtonian\nnecking by increasing the fluid viscosity. In the viscoelastic regime,\nparticles do not affect the thinning until the onset of the blistering\ninstability, which they accelerate. We find that the transition from one regime\nto another, which corresponds to the coil-stretch transition of the polymer\nchains, strongly depends on the particle content. Considering that the presence\nof rigid particles increase the deformation of the liquid phase, we propose an\nexpression for the local strain rate in the suspension, which rationalizes our\nexperimental results. This method could enable the precise measurement of local\nstresses in particulate suspensions.