THE SIMULATION OF CHAOTIC MIXING AND DISPERSION FOR PERIODIC FLOWS IN BAFFLED CHANNELS

We report numerically generated flow visualisation simulations for the flow of an incompressible Newtonian fluid within a two-dimensional channel which can contain periodic baffles. For unsteady flows in this geometry a regime of chaotic advection is observed when baffles are present. The unsteadiness takes one of two forms: a "natural" unsteadiness caused by a symmetry breaking instability of the flow, or a "forced" unsteadiness generated by applying an oscillatory component to the flow. This chaotic advection is shown to provide an efficient mixing mechanism and has a number of applications in the process industry. Enhanced transverse mixing is observed which results in increased transfer properties, reduced fouling rates and, in some circumstances, a reduction in axial dispersion, as recently experimentally reported in the literature.