Chaotic mixing of viscous fluids by periodic changes in geometry: Baffled cavity flow

The baffled cavity flow—the first representative of a class of chaotic flows produced by time‐dependent changes of geometries—is introduced and extensions to spatially‐periodic systems proposed. Both experimental and computational results are reported. The goal of the study is to put into evidence some of the steps and considerations when designing a new mixing flow; a related objective is to demonstrate the use of an efficient and accurate numerical technique (BIEM) suitable for mixing studies in time‐dependent geometries. Several parameters that affect the degree of mixing are studied: the mixing protocol—how the baffles are alternated and how many baffles are used in the flow during each piecewise motion; baffle sizes and shapes; geometrical and flow parameters, such as the wall displacement per period; and details of the baffle's motions.