Brownian dynamics simulations of planar mixed flows of polymer solutions at finite concentrations

Periodic boundary conditions for planar mixed flows are implemented in the context of a multi-chain Brownian dynamics simulation algorithm. The effect of shear rate γ˙, and extension rate ε˙, on the size of polymer chains, 〈Re2〉, and on the polymer contribution to viscosity, η, is examined for solutions of FENE dumbbells at finite concentrations, with excluded volume interactions between the beads taken into account. The influence of the mixedness parameter, χ, and flow strength, Γ˙, on 〈Re2〉 and η, is also examined, where χ→0 corresponds to pure shear flow, and χ→1 corresponds to pure extensional flow. It is shown that there exists a critical value, χ_c, such that the flow is shear dominated for χ<χ_c, and extension dominated for χ>χ_c.