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There is a great need for understanding the relationship between the structure and chemistry of surfactants forming wormlike micelles, and their macroscopic flow properties. Available macroscopic Rheological Equations of State (REoS) are often inadequate to describe the full set of rheological measurements. In this paper we show how the link between surfactant structure and rheology can be explored through the use of mesoscopic particulate simulations. We describe the development of a realistic Brownian Dynamics model, where the persistence length of the micelle is the smallest length scale. Most of the parameters for the BD model are obtained from atomistic Molecular Dynamics simulations to establish the link to the chemistry of the surfactant. As a preliminary result, we calculate the shear viscosity of a solution of entangled wormlike micelles as a function of increasing shear rate. The results can be approximately mapped on an experimental flow curve for this particular system, using a mean-field scaling relationship. Finally, we give experimental results for the flow of the wormlike micellar fluid in an expansion-contraction capillary using micro Particle Image Velocimetry. This demonstrates the complex response of these fluids in non-viscometric flows and the challenges they pose to any predictive simulation model. |