|
|
|
Article
Formation of coherent structures by fluid inertia in three-dimensional laminar flows
| Authors: |
Pouransari, Z., Speetjens, M., Clercx, H. |
| Document Type: |
Article |
| Pubstate: |
Published |
| Journal: |
Journal of Fluid Mechanics |
| Volume: |
654
5-33 |
| Year: |
2010 |
AbstractMixing under laminar flow conditions is key to a wide variety of industrial fluid systems of size extending from microns to meters. Profound insight into three-dimensional (3D) laminar mixing mechanisms is essential for better understanding of the behaviour of such systems and is in fact imperative for further advancement of (in particular microscopic) mixing technology. This insight remains limited to date, however. The present study concentrates on a fundamental transport phenomenon relevant to laminar mixing: the formation and interaction of coherent structures in the web of 3D paths of passive tracers due to fluid inertia. Such coherent structures geometrically determine the transport prop- erties of the flow and thus their formation and topological structure are essential to 3D mixing phenomena. The formation of coherent structures, its universal character and its impact upon 3D transport properties is demonstrated by way of experimentally-realisable time-periodic model flows. Key result is that fluid inertia induces partial disintegration of coherent structures of the non-inertial limit into chaotic regions and merger of surviving parts into intricate 3D structures. This response to inertial perturbations, though exhibiting great diversity, follows a universal scenario and is therefore believed to reflect an essentially 3D route to chaos. Furthermore, a first outlook towards experimental validation and investigation of the observed dynamics is made.
|
|
