Single-polymer dynamics: Coil-stretch transition in a random flow

By quantitative studies of statistics of polymer stretching in an elastic turbulence and the statistical properties of this random flow itself that are characterized by the average Lyapunov exponents of particle pair separations, , we demonstrate that the stretching of polymer molecules in a 3D random flow occurs rather sharply via the coil-stretch transition. The experimental value of the onset of the coil-stretch transition, cr*tau = 0.77 +/- 0.20, where tau is the polymer relaxation time, is found to be rather close to the theoretically predicted one.