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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 $\dotγ$, and extension rate $\dotε$, on the size of polymer chains, $\left<R_e^2\right>$, 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, $\dotΓ$, on $\left<R_e^2\right>$ and $η$, is also examined, where $χ\rightarrow 0$ corresponds to pure shear flow, and $χ\rightarrow 1$ corresponds to pure extensional flow. It is shown that there exists a critical value, $χ_\text{c}$, such that the flow is shear dominated for $χ< χ_\text{c}$, and extension dominated for $χ> χ_\text{c}$.