Mélange et transfert, thermique chaotique dans un écoulement 2D périodique

The annular region between two confocal ellipses is a new mixing geometry defined and constructed in Nancy. When the two walls are displaced following their circumference in opposite directions at constant angular velocity, the steady state streamlines show the appearance of two saddle points joined by two different streamlines, leading thus to heteroclinic trajectories. By an adequate choice of the time-periodic velocity history of the two walls, chaotic trajectories can be obtained in this Stokes flow and only a limited number of periods are necessary to mix a small amount of tracer over the entire domain. The protocol that gives the most rapid mixing is also the one that gives the highest heat transfer rate.