Investigations of Mixing Time Scales in a Baffled Circular Tank with a Surface Aerator

  • Kumar, Bimlesh (Civil Engineering, Indian Institute Technology Guwahati) ;
  • Patel, Ajey (Civil Engineering, Indian Institute Technology Guwahati) ;
  • Rao, Achanta (Civil Engineering, Indian Institute Technology Guwahati)
  • Received : 2010.05.04
  • Accepted : 2011.03.07
  • Published : 2011.03.30


The oxygen transfer rate is a parameter that characterizes the gas-liquid mass transfer in surface aerators. Gas-liquid transfer mechanisms in surface aeration tanks depend on two different extreme lengths of time; namely, macromixing and micromixing. Small scale mixing close to the molecular level is referred to as micromixing; whereas, macromixing refers to mixing on a large scale. Using experimental data and numerical simulations, macro- and micro-scale parameters describing the two extreme time scales were investigated. A scale up equation to simulate the oxygen transfer rate with micromixing times was developed in geometrically similar baffled surface aerators.


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