Confined flow vortex breakdown control using a small rotating disk

As part of a program to investigate the effectiveness of vortex breakdown in bioreactors for cell and tissue growth, a nonintrusive method of flow control is presented. A small rotating disk flush-mounted opposite to the rotating lid in a confined cylindrical vessel is found to precipitate or delay the onset of vortex breakdown depending on whether it is corotating or counterrotating, respectively. Furthermore, corotation increases the bubble radial and axial dimensions while shifting the bubble in the upstream direction. By contrast, counterrotation tends to reduce the size of the bubble, or completely suppress it, while shifting the bubble in the downstream direction. It has also been shown that corotating swirl addition using the small disk is orders of magnitude more energy efficient in manipulating the vortex breakdown bubble than using end wall rotation. © 2004 American Institute of Physics. (DOI: 10.1063/1.1813061)