Unraveling of a Tethered Polymer Chain in Uniform Solvent Flow

The separation of electrophoresing DNA molecules of varying lengths, actuated by their sizedependent collision with a stationary obstacle or array of obstacles, has recently gained prominence. To gain insight into how a chain initially unravels subsequent to a polymer-obstacle collision, we investigate the stretching dynamics of a tethered polymer chain initially at equilibrium, following the imposition of a uniform flow of solvent. The solution for the Rouse model of the polymer chain is obtained via an analysis into normal modes. We examine the consequences of finite chain extensibility by performing Brownian dynamics simulations of the wormlike chain model, which describes DNA elasticity. Detailed results are presented for the propagation of tension with time in Rouse and wormlike chains. Our results suggest the diffusive propagation of tension in Rouse chains, whereas a convective mechanism of tension propagation in wormlike chains under conditions of strong flow is demonstrated.