Micro-macro modeling of polymeric fluids and shear-induced microscopic behaviors with bond-breaking

This paper explores the micro-macro modeling of polymeric fluids using the proposed microscopic elastic-plastic (EP) potential energy, in order to illustrate the effects of irreversible bond-breaking of microscopic polymer chains. Precisely, we first revisit the derivation of a thermodynamically consistent micro-macro model using the energy variational method. To demonstrate the model's predictions, we perform numerical simulations using a deterministic particle finite element method. Our numerical investigations reveal the behaviors of polymer chains with irreversible bond breaking at the microscale and their influence on induced shear stresses and macroscale velocities under shear flow. We also conduct numerical investigations with other classical microscopic potential energies as a comparison, including the Hookean, the FENE (finite extensible nonlinear elastic), and the modified Morse potentials, involving pure elastic, finite extension. and reversible bond breaking, respectively. We find that polymer elongation, rotation, and bond breaking contribute to differences in polymer-induced stresses and velocities in the micro-macro models. Additionally, we observe that at high shear rates, polymer rotation induces shear- thinning behavior in the micro-macro models.