Wormlike micelles under shear flow: A microscopic model studied by nonequilibrium-molecular-dynamics computer simulations

We propose a microscopic model for solutions of wormlike micelles and report results from nonequilibrium-molecular-dynamics computer simulations under shear flow. Our model (''FENE-C'') introduces the concept of scission-recombination and is an extension of a recent model employed by one of us [M. Kroger, Rheologie und Struktur von Polymerschmelzen (Wissenschaft and Technik, Berlin, 1995); Rheology 5, 66 (1995)] for polymer melts. In this study our interest is focused on the relevance of the microscopic model by comparing the results of the simulations with the predictions of mesoscopic theories. The simulated behavior shows an exponential distribution for the micellar length and an exponential dependence of the average length on the scission energy at equilibrium. These results correspond to those calculated from Cates mesoscopic theory. Results of simulations concerning the effect of shear flow on the size distribution and on the average length of the micelles are also reported and discussed.