The shear-induced isotropic-to-lamellar transition in a lattice-gas model of ternary amphiphilic fluids

Abstract

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.

Lattice-Gas Simulations of Ternary Amphiphilic Fluid Flow in Porous Media

“…In this report, as in previous studies [1][2][3][4] β = 1.0 and the coupling constants are given the values α = 1.0 µ = 0.001 ǫ = 8.0 ζ = 0.005, strongly encouraging surfactant molecules to accumulate at oil-water interfaces while maintaining the normal oil-water immiscible behavior. Different porous media have been constructed.…”

“…The lattice gas automaton (LGA) model introduced by Boghosian, Coveney and Emerton [1] has been used to investigate a variety of amphiphilic phenomena including the growth kinetics of binary immiscible fluid and ternary microemulsion systems [2,3], the effect of shear on ternary systems [4] and self-reproducing micelles [5]. In this article we describe the developments that have been made to allow invasive flow within a porous medium to be studied using this model.…”

Large scale molecular dynamics simulation of self-assembly processes in short and long chain cationic surfactants

“…Under these conditions, the dynamical properties of micelles are extremely difficult to study because the time scales of dynamical processes may vary from 10 −11 (presumed characteristic time of shape fluctuations) to 10 4 seconds (relaxation time of some shear-induced structures). The length and timescales involved in selfassembly phenomena correspond typically to the domain of applicability for different mesoscopic models including lattice-gas [10][11][12], lattice-Boltzmann [13,14] and dissipative particle dynamics (DPD) [15,16]. An outstanding challenge for these upscaling methods is the definition of a coherent link between the atomistic description of the sytem and the related meso and macroscopic behaviour.…”

A particulate basis for a lattice-gas model of amphiphilic fluids

“…The lattice-gas models studied in (Emerton et al 1997a, Emerton et al 1997b, Emerton et al 1997c, Emerton et al 1997d, Boghosian et al 2001, Love et al 2001a, Love et al 2001b) have elements of both interpretations. On the one hand lattice gas surfactant particles are regarded as being genuinely molecular in character, whereas in the collision step outgoing states are sampled over Boltzmann weights constructed from the local Hamiltonian.…”

“…The Rothman-Keller model has been used to investigate surface tension and interfacial fluctuations (Adler et al 1994), spinodal decomposition in both two and three dimensions (Appert et al 1995;Rothman & Keller 1988), and the effect of shear on phase separation in three dimensions . Emerton et al (1997a) generalized the Rothman-Keller model by including point surfactant particles possessing a colour dipole. Those authors introduced three additional terms into the Rothman-Keller model.…”