Shear-Induced Isotropic-to-Lamellar Transition in a Lattice-Gas Model of Ternary Amphiphilic Fluids

Although shear-induced isotropic-to-lamellar transitions in ternary systems of oil, water and surfactant have been observed experimentally and predicted theoretically by simple models for some time now, their numerical simulation has not been achieved so far. In this work we demonstrate that a recently introduced hydrodynamic lattice-gas model of amphiphilic fluids is well suited for this purpose: the two-dimensional version of this model does indeed exhibit a shear-induced isotropic-to-lamellar phase transition.Comment: 17 pages, LaTeX with epsf and REVTeX, PostScript and EPS illustrations included. To appear in J. Phys. Cond. Ma

Lattice-gas simulations of Domain Growth, Saturation and Self-Assembly in Immiscible Fluids and Microemulsions

We investigate the dynamical behavior of both binary fluid and ternary microemulsion systems in two dimensions using a recently introduced hydrodynamic lattice-gas model of microemulsions. We find that the presence of amphiphile in our simulations reduces the usual oil-water interfacial tension in accord with experiment and consequently affects the non-equilibrium growth of oil and water domains. As the density of surfactant is increased we observe a crossover from the usual two-dimensional binary fluid scaling laws to a growth that is {\it slow}, and we find that this slow growth can be characterized by a logarithmic time scale. With sufficient surfactant in the system we observe that the domains cease to grow beyond a certain point and we find that this final characteristic domain size is inversely proportional to the interfacial surfactant concentration in the system.Comment: 28 pages, latex, embedded .eps figures, one figure is in colour, all in one uuencoded gzip compressed tar file, submitted to Physical Review

Shear Induced Isotropic-to-Lamellar Transition in a Lattice-Gas Automaton Model of Microemulsions.

We report on the simulation of an isotropic-to-lamellar transition under linear shear flow in a ternary system of oil, water and surfactant. This experimentally observed and theoretically predicted behaviour has not been simulated before. We are able to model the phenomenon by using our recently introduced lattice-gas automaton model of amphiphilic systems, which is well suited for simulating complex multi-phase flows of this nature. PACS numbers: 82.70.-y;05.70.Lm 1 Introduction Soft materials such as polymer solutions, liquid crystals, surfactants, and microemulsions are frequently processed or utilized through the application of large deformations. Various attempts have been made to investigate and characterize the behaviour of such complex systems under conditions such as shear flow where the industrial applications are clear [1]. In this letter we model the effect of linear shear flow on a fully hydrodynamic, isotropic, bicontinuous microemulsion phase using our recently introduc..