An experimental study of falling liquid films

Jones, Leighton O.; Whitaker, Stephen

doi:10.1002/aic.690120324

Cited by 97 publications

(40 citation statements)

References 8 publications

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“…Similar agreement is illustrated in Figure 3 where the dimensionless wave velocity is compared with previous experimental (14) and theoretical work (2, 28).…”

Section: Anshus L Gorensupporting

confidence: 82%

“…The experimental method used in this study is essentially identical to that used by Jones ( 1 3 ) and described elsewhere (14). A schematic representation of the experimental equipment is shown in Figure 1.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…In this method one obtains two signals which are proportional to the slopes of the gas-liquid interface at two points 1.27 cm. apart, and from these two signals the wave length and wave velocity can be determined ( 14 ) . A severe restriction of this experimental set up was that measurements could be made only over the top 11 cm.…”

Section: Experimental Methodsmentioning

confidence: 99%

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The effect of surfactants on the flow characteristics of falling liquid films

Strobel

Whitaker

1969

AIChE Journal

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Experimental values of the wave length and wave velocity have been obtained far dilute sohtions of valeric and hexanoic acid for a vertical fulling liquid film. The wave length was unaffected by the surfactants for Reynolds numbers in the range 5 to 100; however, the wave velocity was decreased for increased surface concentrations of the two acids. This is in direct contradiction to previous theoretical work, and the explanation for the anomaly is that the free surface velocity is greatly retarded by the adsorption of the surface active agents.In an effort to determine the extent of this retardation, an approximate form of the diffusion equation and the equations of motion were solved subject to boundary conditions describing the effect of the adsorbed surfactant on the surface stress. The results indicate that the entrance length can be increased several orders of magnitude by the addition of small amounts of surfactant.The flow characteristics of falling liquid films have been a subject of interest in connection with gas absorption studies (9, 17, 24, 27) primarily because the falling film appears to provide a reasonably well defined interfacial area and contact time. Knowledge of the nature of the flow of thin liquid films is also of importance in analyzing heat transfer rates for ablating space vehicles ( 3 1 ) , in the design of cooling systems for high temperature turbine blades (15), and in the analysis of mass transfer rates in certain desalinization processes ( 6 ) .By itself, the falling liquid film provides a reasonable experimental tool for studying the effect of surface active agents on bulk fluid motion. In addition to the wave length and wave velocity, one can also observe the location (measured from the top of the film) of the first visible waves as a function of Reynolds number, and the rate of approach of the surface velocity to the value predicted for uniform flow.In order to test recent mathematical studies (1, 4, 28, 29) of the stability of vertical falling liquid films, an experimental study of the wave length and wave velocity was planned. In a sense, the experimental study was unsuccessful for the data were obtained under conditions which did not allow the direct comparison of theory and experiment; however, some interesting characteristics of the flow were observed and analyzed, and it seems appropriate to report the results at this time.

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“…Similar agreement is illustrated in Figure 3 where the dimensionless wave velocity is compared with previous experimental (14) and theoretical work (2, 28).…”

Section: Anshus L Gorensupporting

confidence: 82%

Section: Experimental Methodsmentioning

confidence: 99%

See 1 more Smart Citation

The effect of surfactants on the flow characteristics of falling liquid films

Strobel

Whitaker

1969

AIChE Journal

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“…Kapitza's theory, however, is restricted only to long waves and to low flow rates where regular sinusoidal wave motion exists. Later experimental findings for higher flow rates (38,76,80) show that Kapitza's theory is inadequate.…”

Section: Falling Film Hydrodynamicsmentioning

confidence: 99%

“…They pointed out that since the wave motion lost its regularity at some dis tance below the line of wave inception, the only proper location for measuring meaningful wavelength data should be in the immediate vicinity of the line of wave inception. Wave properties were also measured by Stainthorp and Allen (76) and Jones and Whitaker (38). Extensive film thickness data for a variety of liquids were taken by Portalski (62).…”

Section: Falling Film Hydrodynamicsmentioning

confidence: 99%