title: Shear-induced structural transitions in newtonian non-newtonian two-phase flow
abstract: We show the existence under shear flow of steady states in a two-phase region of a brine-surfactant system in which lyotropic dilute lamellar (non-Newtonian) and sponge (Newtonian) phases are coexisting. At high shear rates and low sponge phase-volume fractions, we report on the existence of a dynamic transition corresponding to the formation of a colloidal crystal of multilamellar vesicles (or "onions") immersed in the sponge matrix. As the sponge phase-volume fraction increases, this transition exhibits a hysteresis loop leading to a structural bistability of the two-phase flow. Contrary to single phase lamellar systems where it is always 100%, the onion volume fraction can be monitored continuously from 0 to 100 %.
authors.affiliation: Centre de Physique Moleculaire Optique et Hertzienne, Universite Bordeaux I, 351, Cours de la Liberation, Talence 33400, France.
authors.initials: G
authors.lastname: Cristobal
authors.initials: J
authors.lastname: Rouch
authors.initials: A
authors.lastname: Colin
authors.initials: P
authors.lastname: Panizza