  In this work we study chaotic mixing induced by point micro-rotors in a
bounded two dimensional Stokes flow. The dynamics of the pair of rotors,
modeled as rotlets, are non Hamiltonian in the bounded domain and produce
chaotic advection of fluid tracers in subsets of the domain. A complete
parametric investigation of the fluid mixing as a function of the initial
locations of the rotlets is performed based on pseudo phase portraits. The
mixing of fluid tracers as a function of relative positions of micro-rotors is
studied using finite time entropy and locational entropy. The finite time
locational entropy is used to identify regions of the fluid that produce good
vs poor mixing and this is visualized by the stretching and folding of blobs of
tracer particles. Unlike the case of the classic blinking vortex dynamics, the
velocity field of the flow modeled using rotlets inside a circular boundary is
smooth in time and satisfies the no slip boundary condition. This makes the
considered model a more realistic case for studies of mixing in microfluidic
devices using magnetic actuated microspheres.

Chaotic Dynamics;Fluid Dynamics