A mapping tool using anisotropic unstructured meshes to study mixing in periodic %ows

The objective of the present work is to describe a new mapping tool using anisotropic unstructured meshes to study mixing within a spatially periodic pipe %ow. Instead of tracking the boundaries of elementary cell %ow domains as it was done in the original mapping method established by Kruijt et al. (A.I.Ch.E. J. 47 (5) (2001a) 1005; Int. Polym. Process. 16 (2) (2001b) 151) and Galaktionov et al. (Comput. Fluids 30 (3) (2001) 271), the deformation of elementary triangles (only three nodal points) between the inlet and exit pipe cross-sections is followed. It is however necessary to adapt the initial mesh according to criteria which takes into account the spatial stretching and folding of %uid elements. The method developed is applied to the twisted curved pipes (TCP) three-dimensional (3D) %ow. We show the evolution of concentration distributions along the TCP mixer for chaotic advection %ow regimes. This method allows the emphasis of isolated unmixed regions (KAM islands). The %exibility of the method allows also the possibility of studying multiple stirring protocols, thus contributing to a better comprehension of the physical phenomena involved in chaotic mixing. The method developed is also applicable to 2D temporally periodic %ows. ? 2004 Elsevier Ltd. All rights reserved.