Mechanism to explore lamination rate.

A mechanism amenable to laminate and fold flows is identified and quantified. This laminating mechanism follows from a physical and experimental approach relying on the interlaced structure of velocity and Lagrangian acceleration. The Lagrangian acceleration being the resultant of the forces applied on particle fluids, the component of acceleration perpendicular to the velocity vector allows the quantification of a rate of change of the velocity's direction, i.e., the local angular Lagrangian velocity, theta. The spatial variation in theta is then used to predict and measure the lamination and folding rate. To support and illustrate this approach, three basic experimental flows, driven by electromagnetic forces, are discussed and compared. Folding rate intensities are extracted for different characteristic length scales. Also, good agreement is found between grid deformation and the prediction of lamination rate. This quantification of lamination rate opens new avenues for the design of mixers, in particular at low Reynolds numbers.