CUCEI, Universidad de Guadalajara
Plenary Lecture: "Out of Thermodynamic Equilibrium Phase Transitions Induced by Shear Flow"
The phase transition out of thermodynamic equilibrium in the shear as well as in the vorticity flow directions are examined here, which can be predicted with the extended Bautista-Manero-Puig (BMP) model, deduced from the Extended Irreversible Thermodynamics (EIT). In the shear flow direction, shear banding is produced at a critical shear rate or a critical shear stress, at which the flow induces the coexistence of two shear bands in parallel plates or in cone-and-plate geometry, when one phase is isotropic and the other nematic, when the worm-like micellar solution is examined. The isotropic band develops at the low moving plate and the nematic forms at the fast moving plate; this phase separation and coexutence is referred as shear banding flow. In Couette rheometry, several bands in the vorticity direction form under shear flow due to the coexistence of two different phases in the low concentration regime of the worm-like micellar solutions. These phase transitions out of equilibrium can be predicted with the extended BMP model, which demonstrate the existence of phase coexistence in the shear or in the vorticity direction. These flow phenomena resemble a thermodynamic P-V-T phase diagrams, predicted by cubic equations of state. But in the flow of complex fluids such as worm-like micelles, two phases out of equilibrium coexist in the shear flow direction or in the vorticity flow directions.