Dynamics of a polymer under multi-gradient fields

Effects of multi-gradient fields on the transport of a polymer chain are investigated using Langevin dynamics simulations. We observe that the natural frequency of tumbling follows Wi ^0.66 scaling, where Wi is the Weissenberg number. The distribution of angular tumbling time has exponentially decaying tails, and at high Wi, it deviates from Poisson behavior. Competition between the velocity gradient, which results in a shear flow in the system, and the solvent quality gradient arising due to the interaction among monomers reveals that there is another scaling associated with the angular tumbling time distribution. Moreover, at low temperature, we observe unusual behavior that at intermediate shear rates, the decay rate ν decreases with Wi.