Circulation in bubble columns: Corrections for distorted bubble shape

Circulation and scale‐up in bubble columns

“…The aspect ratio, a, represents the height to breadth ratio of an ellipsoidal bubble. This is necessary since the size of eddies formed behind bubbles will be proportional to the major axis (Fan and Tsuchiya, 1990), as discussed recently by Geary and Rice (1991). The implied dependence of turbulence length scale on eddy width is consistent with Prandtl's original hypothesis which required that "the mixing length (P) be proportional to the width of the turbulent mixing zone" (Hinze, 1975).…”

“…Clark et al (1987) and Devanathan et al (1990) recommend the use of a single-phase length scale as measured by Nikuradse (from Schlichting, 1960). In contradiction to this, Rice and Geary (1990) and Geary and Rice (1991) argue that the proposed mixing length scale should be made proportional to the bubble size. Such an approach could be based on the premise that the vortices produced in the wake of a bubble would suppress the latent turbulence arising at the wall from liquid circulation and would therefore dominate local mixing.…”

“…In the two-phase analysis, consideration must also be given to turbulence arising from the movement of bubbles. This scale, based naturally on bubble size and population density, was modified recently (Geary and Rice, 1991) to account for deformed, ellipsoidal-shaped bubbles:…”

New Evidence for the Mixing Length Concept in a Narrow Bubble Column Operated in the Transition Regime

“…Rice and Geary (1990) and Geary and Rice (1991) argue that the mixing length scale should be proportional to the bubble diameter d b . In this case the local mixing is dominating.…”

Comparison of Oxygen Transfer Parameters from Four Testing Methods in Three Activated Sludge Processes

“…In the case of diffused aeration, diffuser-related variables including the orifice diameter, bubble diameter, material of construction, depth of submergence, airflow rate per diffuser, layout, diffuser density, wetting property and fouling nature influence clean water oxygen transfer (Bowers 1955;Eckenfelder 1959;Barnhart 1969;Mavinic and Bewtra 1974;Motarjemi and Jameson 1978;Huibregtse et al 1983;Boyle and Redmon 1983;U.S. EPA 1989a,b;Geary and Rice 1991;Ashley et al 1991Ashley et al , 1992Kim and Boyle 1993;Fujie et al 1997;Mueller et al 2002). Based on a large number of studies a clean water oxygen-transfer standard was established to measure the oxygenation capacity of aeration devices (ASCE 1992).…”