Work fluctuations in an elastic dumbbell model of polymers in planar elongational flow.

We use a path-integral approach to calculate the distribution P(w,t) of the fluctuations in the work w at time t of a polymer molecule (modeled as an elastic dumbbell in a viscous solvent) that is acted on by an elongational flow field having a flow rate ̇γ. We find that P(w,t) is non-Gaussian and that, at long times, the ratio P(w,t)/P(-w,t) is equal to exp[w/(k(B)T)], independent of ̇γ. On the basis of this finding, we suggest that polymers in elongational flows satisfy a fluctuation theorem. ©2011 American Physical Society