Shear Banding — Soft Matter Couette Flow Instability

Wormlike micellar solution in Couette geometry. Non-monotonic flow curve leads to coexisting high- and low-viscosity bands.

Rheology Parameters

Band fraction: —
Shear banding (Rehage & Hoffmann 1991): when the constitutive curve σ(γ̇) is non-monotonic (N-shaped), the system phase-separates into coexisting bands at the same stress σ_plateau (Maxwell construction). Common in wormlike micelles, dense emulsions, dense polymers. The interface diffusion term D sets band width.