Prediction of Shear-Banding in Flowing Micellar Systems

In recent years, several experimental works on worm-like micelles have shown that a “dynamical phase separation” can arise in these systems when subjected to shear. At steady state, and beyond some critical value of the imposed shear rate, a banded structure can be found, with bands parallel to the velocity direction. Both birefringence measurements (Makhloufi et al., 1995) and direct NMR velocity imaging (Britton and Callaghan, 1997) indicate that bands are actually identified by sharply different values of the local shear rate. The material self-organizes by “splitting” the imposed, nominal shear rate in high-shear and low-shear bands. Details of this process are still largely unknown, however, and explanations and predictions from theory are scarce.