Wall slip across the jamming transition of soft thermoresponsive particles

Abstract

Flows of suspensions are often affected by wall slip, that is the fluid velocity $v_f$ in the vicinity of a boundary differs from the wall velocity $v_w$ due to the presence of a lubrication layer. While the slip velocity $v_s=|v_f-v_w|$ robustly scales linearly with the stress $\sigma$ at the wall in dilute suspensions, there is no consensus regarding denser suspensions that are sheared in the bulk, for which slip velocities have been reported to scale as a $v_s\propto {\sigma }^p$ with exponents $p$ inconsistently ranging between 0 and 2. Here we focus on a suspension of soft thermoresponsive particles and show that $v_s$ actually scales as a power law of the viscous stress $\sigma -{\sigma }_c$, where ${\sigma }_c$ denotes the yield stress of the bulk material. By tuning the temperature across the jamming transition, we further demonstrate that this scaling holds true over a large range of packing fractions $\varphi$ on both sides of the jamming point and that the exponent $p$ increases continuously with $\varphi$, from $p=1$ in the case of dilute suspensions to $p=2$ for jammed assemblies. These results allow us to successfully revisit inconsistent data from the literature and paves the way for a continuous description of wall slip above and below jamming.

6 pages, 4 figures - accepted for publication as a Rapid Communication in Phys. Rev. E

References in corpus (3)

• Microfluidic rheology of soft colloids above and below jamming
• Influence of boundary conditions on yielding in a soft glassy material
• Avalanche-like fluidization of a non-Brownian particle gel

Cited by in corpus (7)

• Yield Stress Materials in Soft Condensed Matter
• Ductile-to-brittle transition and yielding in soft amorphous materials: perspectives and open questions
• Local Oscillatory Rheology from Echography
• Deformation profiles and microscopic dynamics of complex fluids during oscillatory shear experiments
• Slippery flows of a Carbopol gel in a micro-channel
• On the impact of controlled wall roughness shape on the flow of a soft-material
• Wall slip and bulk yielding in soft particle suspensions