Numerical and experimental characterization of a family of two–roll–mill flows

Two–dimensional creeping flow generated by a two–roll mill in a cylindrical domain is investigated numerically and experimentally for arbitrary ratios Ø of the angular velocities of the inner cylinders. The Stokes flow in the two–roll–mill domain is computed for various values of Ø using a least–squares approach, and it is compared with experimental visualizations of the flow field. This combined numerical and experimental study, together with critical–point concepts, has been used to uncover the complete sequence of complex transitions between the extreme cases of counter– and co–rotation. The results lead us to speculate that a continuous variation between the two end states may lead to an efficient chaotic advective mixer.