Numerical study of polymer tumbling in linear shear flows

We investigate numerically the dynamics of a single polymer in a linear shear flow. The effects of thermal fluctuations and randomly fluctuating velocity gradients are both analyzed. Angular, elongation and tumbling time statistics are measured numerically. We perform analytical calculations and numerical simulations for a linear single-dumbbell polymer model comparing the results with previous theoretical and experimental studies. For thermally driven polymers the balance between relaxation and thermal fluctuations plays a fundamental role, whereas for random velocity gradients the ratio between the intensity of the random part and the mean shear is the most relevant quantity. In the low-noise limit, many universal aspects of the motion of a polymer in a shear flow can be understood in this simplified framework.