Edge fracture in complex fluids

Abstract

We study theoretically the edge fracture instability in sheared complex fluids, by means of linear stability analysis and direct nonlinear simulations. We derive an exact analytical expression for the onset of edge fracture in terms of the shear-rate derivative of the fluid's second normal stress difference, the shear-rate derivative of the shear stress, the jump in shear stress across the interface between the fluid and the outside medium (usually air), the surface tension of that interface, and the rheometer gap size. We provide a full mechanistic understanding of the edge fracture instability, carefully validated against our simulations. These findings, which are robust with respect to choice of rheological constitutive model, also suggest a possible route to mitigating edge fracture, potentially allowing experimentalists to achieve and accurately measure stronger flows than hitherto.

5 pages, 4 figures (plus Supplementary Material); v2: updated to post-referee version, incl. minor update to Fig. 1

References in corpus (1)

• Moving contact line dynamics: from diffuse to sharp interfaces

Cited by in corpus (4)

• Edge fracture instability in sheared complex fluids: onset criterion and possible mitigation strategy
• A new pressure sensor array for local normal stress measurement in complex fluids
• Edge-induced shear banding in entangled polymeric fluids
• Interplay of edge fracture and shear banding in complex fluids