Vortex breakdown in a truncated conical bioreactor

Adnan Balci, Morten Brøns, Miguel A. Herrada, Vladimir N. Shtern

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Abstract

This numerical study explains the eddy formation and disappearance in a slow steady axisymmetric air–water flow in a vertical truncated conical container, driven by the rotating top disk. Numerous topological metamorphoses occur as the water height, Hw, and the bottom-sidewall angle, α, vary. It is found that the sidewall convergence (divergence) from the top to the bottom stimulates (suppresses) the development of vortex breakdown (VB) in both water and air. At α = 60°, the flow topology changes eighteen times as Hw varies. The changes are due to (a) competing effects of AMF (the air meridional flow) and swirl, which drive meridional motions of opposite directions in water, and (b) feedback of water flow on AMF. For small Hw, the AMF effect dominates. As Hw increases, the swirl effect dominates and causes VB. The water flow feedback produces and modifies air eddies. The results are of fundamental interest and can be relevant for aerial bioreactors.
Original languageEnglish
Article number065503
JournalFluid Dynamics Research
Volume47
Issue number6
Number of pages26
ISSN0169-5983
DOIs
Publication statusPublished - 2015

Keywords

  • Vortex breakdown
  • Flow topology
  • Moffatt eddies
  • Bioreactors
  • Axisymmetric flow

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