ISOLATED MIXING REGIONS - ORIGIN, ROBUSTNESS AND CONTROL

Isolated mixing regions (IMRs) are fluid regions that may or may not h ave interior mixing and are usually located far away from boundaries; however, they do not exchange material with regions of active global m ixing and they therefore present a substantial obstacle to global mixi ng. Islands in two dimensions and tubes and tori in three dimensions a re examples of IMRs. We investigate interrelated issues dealing with I MR detection and prediction, robustness, exploitation and control of I MRs using experiments and computations carried out in two model system s. Results indicate that it is possible to manipulate the area of IMRs in a controlled fashion, hence creating an analog of a controlled rel ease capsule within a chaotic flow. (C) 1997 Elsevier Science Ltd.