Effect of frother on initial bubble shape and velocity

The effect of bubble release techniques on their behaviour at the initial stages of rise

“…They also observed that with the accumulation of surfactants the studied systems never reached a stable terminal velocity. The results of Kracht and Finch (2010) also show velocity fluctuations confirming dynamic effects to take place. Their results also show that the bubble velocities immediately after release (t < 10 ms) were not functions of frother concentration or chemical structure.…”

“…It is well known that the bubble surface in an ultra pure system is mobile and hence the terminal rising velocity is higher than that of a solid sphere of identical diameter and density (Hadamard, 1911;Rybczynski, 1911) but that adsorbed surfactants retard the terminal velocity due to the increased drag force. There is large body of research confirming this also with flotation frothers (Fuerstenau and Wayman, 1958;Aybers and Tapucu, 1969a,b;Sam, 1995;Ybert and di Meglio, 1998;Zhang et al, 2001;Krzan and Malysa, 2002;Krzan et al, 2004Krzan et al, , 2007Wu and Gharib, 2002;Kracht and Finch, 2010).…”

“…Their results also show that the bubble velocities immediately after release (t < 10 ms) were not functions of frother concentration or chemical structure. Acuna (2007), Finch et al (2008 and Kracht and Finch (2010) observed that the effects of surfactant adsorption started to appear after 10 ms. Bubble aspect ratio and velocity became functions of surfactant concentrations and showed effects of the structure of the surfactant.…”

“…The method allows releasing constant size bubbles with controlled Eotvos numbers (Kracht and Finch, 2010). At the creation of a bubble the adsorption starts immediately when the gas-liquid boundary is formed.…”

Motion of partially contaminated bubbles in power-law liquids: Effect of wall retardation

“…Sam et al (1996) in their experimental investigation found that terminal velocity is a function of frother type but not concentration. Kracht and Finch (2010) studied the effect of frother on initial bubble shape and velocity and concluded that the increasing concentration of frother bubble becomes spherical and depends on frother type as well. Thus, on the basis of both experimental and numerical research, adequate information is now available on the momentum transfer characteristics of partially contaminated single bubbles in unconfined surfactant-laden Newtonian liquids at least in the steady axisymmetric flow regime.…”