http://calliope.dem.uniud.it/CLASS/EPFL-COURSE/Tomyama-Zun-CES-2002.pdf

Transverse migration of single bubbles in simple shear flows

Terminal velocity of single bubbles in surface tension force dominant regime

An investigation of the effects of various physical properties, drop size, and drop velocity on drop shape was carried out for nonoscillating liquid drops falling through stationary liquid continuous phases. The data of forty-five dispersed-continuous phase systems were studied with continuous phase viscosities varying from 0.3 to 46 centipoise and interfacial tensions varying from 0.3 to 42 dyne/cm. A theoretical relation was obtained from the Taylor and Acrivos analysis which quite accurately predicts drop eccentricities for drop Reynolds numbers less than about 20, but is highly inaccurate at higher Reynolds numbers. Relatively simple empirical relations involving the Weber number, Eotvos number, and viscosity ratio were obtained which enable the prediction of the eccentricity of nonoscillating drops over a wide range of Reynolds numbers (6.0 to 1,354) with average deviations of 6 to 8%. These relations may be useful in the estimation of the interfacial area, velocity, and continuous phase mass transfer coefficient of drops distorted from spherical shape.

Shape of liquid drops moving in liquid media

Drop deformation and breakup due to shock wave and steady disturbances

Numerical simulation of the dynamic flow behavior in a bubble column : A study of closures for turbulence and interface forces

Rates of mass transfer during drop formation and coalescence were investigated for three dispersed phase-controlled liquid systems, one binary (ethyl acetate-water) and two ternary (acetic acid-chlorobenzene-water and acetic acid-50% by volume mixture of carbon tetrachloride and nujol-water). A calculation procedure was devised to isolate these end effects. The measured rates during drop formation were in general greater than predicted by various theoretical models, including those by Heertjes et al. and Ilkovic; and measurements during drop coalescence were in general lower than predicted by the simplified penetration theory model of Johnson and Hamielec. The results were statistically correlated with average absolute deviations of 26.2 and 25.4%, respectively, for drop formation and coalescence.

Dispersed phase mass transfer during drop formation and coalescence in liquid-liquid extraction

Extraction with single turbulent droplets

This experimental study shows effects of anionic and cationic surface active agents on mass transfer during drop formation, fall, and coalescence for both continuous and disperse phase-controlled systems. Three dispersion nozzles, mounted with 1.906 cm equilateral pitch, and a 5.08 cm I.D. extraction column were used to simulate certain conditions in commercial liquid-liquid extraction units.



The surfactant effects on extraction were pronounced, frequently reducing transfer to 10% of that in uncontaminated systems, with marked minima at intermediate concentrations of surfactant. In contrast, the continuous phase coefficient during coalescence was substantially increased by surfactants, with maxima in some cases.

Effects of surface active agents on mass transfer during droplet formation, fall, and coalescence

The boundary-layer equations and a Blasius type of relationship between f and NRe gen are used to derive expressions for velocity distribution, local boundary-layer thickness, local shear stress, and total drag force for the turbulent boundary-layer flow of a power law non-Newtonian fluid across a flat plate at zero incidence. Relationships are derived for the velocity at the edge of the laminar sublayer and for the thickness of the laminar sublayer.

An analogy between heat and momentum transfer is then used to obtain expressions for local and mean values of the heat transfer coefficient in a turbulent thermal boundary layer for power law materials flowing over flat plates. Analogous extensions to mass transfer are indicated.

A tentative criterion is suggested for characterizing the transition from laminar to turbulent boundary-layer flow of power law fluids.

Relationships combining the effects of a part laminar, part turbulent boundary layer are presented.

A. H. P. Skelland

Papers

Shape of liquid drops moving in liquid media

Dispersed phase mass transfer during drop formation and coalescence in liquid-liquid extraction

Extraction with single turbulent droplets

Effects of surface active agents on mass transfer during droplet formation, fall, and coalescence

Momentum, heat, and mass transfer in turbulent non-Newtonian boundary layers