Comparison of lattice-Boltzmann and Brownian-dynamics simulations of polymer migration in confined flows

This paper compares results from lattice-Boltzmann and Brownian-dynamics simulations of polymer migration in confined flows bounded by planar walls. We have considered both a uniform shear rate and a constant pressure gradient. Lattice-Boltzmann simulations of the center-of-mass distribution agree quantitatively with Brownian-dynamics results, contradicting previously published results. The mean end-to-end distance of the extended polymer is more sensitive to grid resolution Delta x and time-step Delta t. Nevertheless, for sufficiently small Delta x and Delta t, convergent results for the polymer stretch are obtained which agree with Brownian dynamics within statistical uncertainties. The Brownian-dynamics simulations incorporate a mobility matrix for a confined polymer that is both symmetric and positive definite for all physically accessible configurations.