Interplay of wall slip and shear banding in wormlike micelle solutions

Despite the frequent coexistence of shear banding and wall slip in flowing wormlike micelle (WLM) solutions, the influence of wall slip on the spatiotemporal evolution of the flow field during shear banding has not been systematically explored. Here, shear-banded cylindrical Couette flows of WLMs described by the Germann–Cook–Beris model are simulated with wall slip. Two simple slip conditions – one proportional to shear rate and the other proportional to shear stress – motivated by datasets quantifying wall slip with shear banding are considered. In steady shear, introducing wall slip of either form delays the onset of shear banding and reduces the width of the high-shear-rate band, consistent with experiments. During shear startup, wall slip dampens the magnitude of the apparent shear rate, which extends the time for shear-banded flow to develop. The complex evolution of the flow field during shear-band formation produces large variations of the slip velocity, which enhance or diminish the degree of elastic recoil and flow reversal depending on the slip condition. This work demonstrates that the incorporation of wall slip into shear-banding simulations via simple slip boundary conditions can improve the qualitative agreement between models of shear banding in WLMs and experiments.