On the breakup of a thin liquid film subject to interfacial shear

Abstract

The breakup of a thin non-evaporating liquid film that is either flowing down or climbing on a vertical or inclined surface and subject to cocurrent or countercurrent interfacial shear (or gas flow) is investigated analytically. Analytical expressions for the dimensionless liquid film thickness, $\Delta_{\hbox{\scriptsize\it min}}$, and wetting rate, $\Gamma_{\hbox{\scriptsize\it min}}$, at breakup are derived based on the minimization of the total energy of a stable rivulet, formed following the film breakup. For a downflowing liquid film, increasing the cocurrent interfacial shear (or gas velocity) or decreasing the equilibrium contact angle, $\theta_{o}$, decreases both $\Delta_{\hbox{\scriptsize\it min}}$ and $\Gamma _{\hbox{\scriptsize\it min}}$, below their values with zero interfacial shear. Conversely, increasing the countercurrent interfacial shear or $\theta_{o}$, increases both $\Delta_{\hbox{\scriptsize\it min}}$ and $\Gamma_{\hbox{\scriptsize\it min}}$, above their values with zero interfacial shear. The predictions of $\Delta _{\hbox{\scriptsize\it min}}$ and $\Gamma _{\hbox{\scriptsize\it min}}$ for a climbing water film on a vertical surface are in good agreement with reported experimental data for a wide range of cocurrent gas velocities.

CFD Study on Liquid Flow Behavior on Inclined Flat Plate Focusing on Effect of Flow Rate

“…Since it is very difficult to carry out experimental studies inside packed columns, numerous researchers pay attention to a single inclined plate (Ghiaasiaan et al, 1997;Johnso, 1999;Karimi and Kawaji, 2000;Nicolaiewsky, 1999;Saber and El-Genk, 2004;Takahama and Kato, 1980;Zapke and Kröger, 2000). Some qualitative and quantitative conclusions were drawn by the experimental observation and analysis.…”

Unidirectional flow of a thin rivulet on a vertical substrate subject to a prescribed uniform shear stress at its free surface

“…Various aspects of rivulet flow in the presence of significant surface-shear forces have been investigated by, for example, Mikielewicz and Moszynski, 1 Eres, Schwartz, and Roy, 2 Wilson, Duffy, and Hunt, 3 Myers, Liang, and Wetton, 4 and Saber and El-Genk. 5 In this Brief Communication we use the lubrication approximation to analyze the steady unidirectional flow of a thin rivulet on a vertical substrate subject to a prescribed uniform longitudinal shear stress at its free surface.…”

A thin rivulet of perfectly wetting fluid subject to a longitudinal surface shear stress

“…It would also be interesting to investigate the effect of a prescribed transverse surface shear stress on a rivulet. More generally, the study of more sophisticated models for the effect of an external airflow, such as the non-uniform pressure distribution used by McKinley and Wilson (6) and non-uniform longitudinal surface shear stress used by Saber and El-Genk (17) or genuinely coupled models such as that used by King and Tuck (1) 1.5618n …”