Chaotic mixing of viscous liquids: recent developments and applications

The author summarizes recent experimental and computational work in mixing of viscous fluids, making special reference to chaotic mixing. The objectives are to put into evidence basic mixing mechanisms, to highlight the potentialities and limitations of direct numerical simulations, and to point out the implications of the concepts in the interpretation of experimental results and in the design of mixing devices. The points to be covered are the following: illustration of basic concepts in terms of mixing in two-dimensional time-periodic flows; extension of the ideas to three-dimensional flows in spatially periodic and time-periodic systems and illustration of concepts leading to an improvement of mixing. The first part of the presentation involves passive Newtonian fluids; recent results involving viscoleastic and immiscible fluids are presented as well.