Experimental Study of Evaporation in the Contact Line Region of a Thin Film of Hexane

1985 ◽  
Vol 107 (1) ◽  
pp. 182-189 ◽  
Author(s):  
P. C. Wayner ◽  
C. Y. Tung ◽  
M. Tirumala ◽  
J. H. Yang
Keyword(s):  
Liquid Film ◽  
Contact Line ◽  
Thin Liquid Film ◽  
Bulk Composition ◽  
Transport Processes ◽  
Shear Stresses ◽  
Strong Function ◽  
Thickness Profile ◽  
Line Region ◽  
Curvature Gradient

The transport processes in the contact line region (junction of evaporating thin liquid film, vapor, and substrate) of stationary steady-state evaporating thin films of hexane with various bulk compositions were studied experimentally. The substrate temperature distribution and liquid film thickness profile were measured, analyzed, and compared with previous results on other systems. The results demonstrate that small changes in the bulk composition significantly alter the characteristics of the transport processes in the contact line region. The curvature gradient at the liquid-vapor interface is a strong function of evaporation rate and composition. Concentration and temperature gradients give interfacial shear stresses and flow patterns that enhance contact line stability.

Use of Scanning Microphotometer to Determine the Evaporative Heat Transfer Characteristics of the Contact Line Region

1981 ◽  
Vol 103 (2) ◽  
pp. 325-330 ◽  
Author(s):  
R. Cook ◽  
C. Y. Tung ◽  
P. C. Wayner
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Flux ◽  
Contact Line ◽  
Heat Transfer Characteristics ◽  
Thin Film Thickness ◽  
Thickness Profile ◽  
Line Region ◽  
Evaporative Heat Transfer

A scanning microphotometer was used to measure in situ the profile of an evaporating decane meniscus in the contact line region on a smooth inclined silicon substrate as a function of the evaporative heat flux. The use of this new experimental design to determine the effect of heat flux on the profile in the contact line region is discussed. The results support the hypothesis that fluid flow in the contact line region of an evaporating thin film results from a change in the thin film thickness profile.

A Study of an Oscillating Corner Meniscus With Phase Change Using Image Analyzing Interferometry

Volume 4 ◽  
2004 ◽  
Author(s):  
Sashidhar S. Panchamgam ◽  
Shripad J. Gokhale ◽  
Joel L. Plawsky ◽  
Sunando DasGupta ◽  
Peter C. Wayner
Keyword(s):  
Fluid Flow ◽  
Phase Change ◽  
Contact Line ◽  
Quartz Substrate ◽  
Thin Liquid Film ◽  
Adsorbed Film ◽  
Line Region ◽  
The Stability ◽  
First Time

The thickness and curvature profiles in the contact line region of a moving evaporating thin liquid film of pentane on a quartz substrate were measured for the thickness region, δ < 2.5 microns. The critical region, δ < 0.1 microns, was emphasized. The profiles were obtained using image analyzing interferometry and an improved data analysis procedure. The precursor adsorbed film, the thickness, the curvature, and interfacial slope (variation of the local “apparent contact angle”) profiles were consistent with previous models based on interfacial concepts. Isothermal equilibrium conditions were used to evaluate the Hamaker constant in-situ and to verify the accuracy of the procedures. The profiles give fundamental insights into the phenomena of phase change, pressure gradient, fluid flow, spreading, and the physics of interfacial phenomena in the contact line region. The experimental results demonstrate explicitly for the first time, with microscopic detail, that the disjoining pressure controls fluid flow within an evaporating completely wetting thin curved film and the stability of the thin film. The change in the thickness of the adsorbed film with time is demonstrated for the first time.

Effect of slip on the contact-line instability of a thin liquid film flowing down a cylinder

2020 ◽  
Vol 101 (5) ◽  
Author(s):  
Chicheng Ma ◽  
Jianlin Liu ◽  
Mingyu Shao ◽  
Bo Li ◽  
Lei Li ◽  
...  
Keyword(s):  
Liquid Film ◽  
Contact Line ◽  
Thin Liquid Film

The Impact of Bubble Dynamic Behaviors on Liquid Film in Open Capillary Microgrooves

2011 ◽  
Author(s):  
Yang Cao ◽  
Xuegong Hu ◽  
Dawei Tang ◽  
Chaohong Guo ◽  
Xuelei Nie
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Contact Line ◽  
Thin Liquid Film ◽  
Maximum Speed ◽  
Phase Contact ◽  
Bubble Dynamic ◽  
Dynamic Behaviors ◽  
Liquid Drops ◽  
The Impact

In this paper, the characteristics of bubble dynamic behaviors and the impacts on the triple-phase contact line are studied by a visualization investigation. A high-speed digital camera with maximum speed of 30000 frames per second is adopted to record the period of bubble growth and the geometry of the splashed liquid drops. The information of the bubble dynamic behavior and the liquid drops volume can be analyzed through the software MATLAB. The statistics of the splashed liquid drops is adopted under different heat flux conditions. The experimental results show that the bubble dynamic behaviors lead to the fluctuation of the triple-phase contact line and the splashed liquid drops make the heat transfer capability of the film in microgrooves less than its theoretical maximum value. The investigation indicates that the bubble behaviors can influence the performance of heat transfer through the fluctuations of the triple-phase contact line in the thin liquid film in microgrooves. And the splashed liquid drops appearing in boiling process can also affect the heat transfer of the liquid film in open capillary microgrooves.

Precursor Film Formation Process Ahead Macroscopic Contact Line of Spreading Droplet on Smooth Substrate

2009 ◽  
Author(s):  
Ichiro Ueno ◽  
Kanji Hirose ◽  
Yusuke Kizaki ◽  
Yoshiaki Kisara ◽  
Yoshizumi Fukuhara
Keyword(s):  
Liquid Film ◽  
Contact Line ◽  
Formation Process ◽  
High Speed ◽  
Thin Liquid Film ◽  
Solid Substrate ◽  
Precursor Film ◽  
Boundary Line ◽  
Brewster Angle Microscopy ◽  
Droplet Spreading

The authors pay their special attention to formation process of wafer-thin liquid film, known as ‘precursor film,’ ahead moving macroscopic contact line of a droplet spreading on a solid substrate. The spreading droplet on the solid substrate is accompanied with the movement of a visible boundary line so-called ‘macroscopic contact line.’ Existing studies have indicated there exits a thin liquid film known as ‘precursor film’ ahead the macroscopic contact line of the droplet. The present author’s group has dedicated their special effort to detect the formation process of the precursor film by applying a convectional laser interferometry and a high-speed camera, and to evaluate the spreading rate of the precursor film. In the present study, existing length of the precursor film at a very early stage of the droplet spreading is evaluated by applying a Brewster-angle microscopy as well as the interferometer. The authors extend their attention to the advancing process of the precursor film on inclined substrate.

Transport to a Chemically Active Thin Liquid Film Over a Spinning Disk

1998 ◽  
Vol 120 (4) ◽  
pp. 293-298 ◽  
Author(s):  
M. M. Rahman
Keyword(s):  
Reynolds Number ◽  
Liquid Film ◽  
Reaction Rate ◽  
Separation Of Variables ◽  
Thin Liquid Film ◽  
Transport Processes ◽  
Space Environment ◽  
Species Concentration ◽  
Ekman Number ◽  
Spinning Disk

An analytical solution for the process of mass transfer from a spinning disk to a chemically active thin liquid film flowing over the disk is presented. By analogy, the results are also applicable to heat transfer to the film with temperature-dependent heat generation. The process is modeled by establishing equations for the conservation of mass, momentum, and species concentration, and solving them analytically. The partial differential equation for species concentration is solved using the separation of variables technique along with the application of the Duhamel’s theorem. Tables for eigenvalues and eigenfunctions are presented for a number of reaction rate constants. A parametric study was performed using Reynolds number, Ekman number, and chemical reaction rate as parameters. It was found that Sherwood number increases with Reynolds number (flow rate) as well as inverse of Ekman number (rate of rotation). These fundamental results will be useful to design advanced energy transport processes for a low-gravity space environment.

Measuring the Changing Composition and Mass of Evaporating Fuel Films

2006 ◽  
Author(s):  
Peter Kelly-Zion ◽  
Catherine Jelf ◽  
Christopher Pursell ◽  
Susan Oxley
Keyword(s):  
Liquid Film ◽  
Evaporation Rate ◽  
Thin Liquid Film ◽  
Engine Performance ◽  
Liquid Films ◽  
Transport Processes ◽  
Pollutant Emissions ◽  
Volatile Components ◽  
Slow Evaporation ◽  
Ft Ir

When a fuel spray impinges on an interior surface of an engine, a thin liquid film can form. The relatively slow evaporation of the film has been shown to be a cause of increased pollutant emissions and reduced engine performance. To improve the understanding of how fuel films affect engine emissions and performance, a research program was initiated to study the physical processes involved in the evaporation of films composed of mixtures of hydrocarbons. The specific goal of the research reported here is to develop a method of simultaneously measuring the mass and composition of evaporating films. This method enables one to compute the evaporation rate of each component in the film. To our knowledge, these composition measurements are the first direct, time-resolved measurements of the changing composition of an evaporating liquid film composed of multiple volatile components. Mass and composition of evaporating liquid films were measured quantitatively using a Fourier transform infrared spectrometer (FT-IR). Evaporation rates for pure solvents and mixtures were determined through a calibration of the FT-IR measurements and these results were validated by measurements acquired with an analytical balance. The FT-IR also measured compositional changes for bi-component mixtures during the evaporation process. Three of the hydrocarbon solvents studied were hexane, cyclohexane, and 3-methylpentane. These were chosen for their similarities in molecular weight and physical properties as well as their comparatively unique infrared absorption spectra. Isooctane was also used because of its prevalence as a gasoline substitute in many engine studies and because of its slow evaporation rate compared to the smaller hydrocarbons. Solvents were studied individually and in various mixtures. Based on these preliminary results the method developed here is expected to be an important tool for studying the transport processes in an evaporating film.

Experimental Determination of the Effect of Disjoining Pressure on Shear in the Contact Line Region of a Moving Evaporating Thin Film

2005 ◽  
Vol 127 (3) ◽  
pp. 231-243 ◽  
Author(s):  
Sashidhar S. Panchamgam ◽  
Shripad J. Gokhale ◽  
Joel L. Plawsky ◽  
Sunando DasGupta ◽  
Peter C. Wayner,
Keyword(s):  
Fluid Flow ◽  
Contact Line ◽  
Quartz Substrate ◽  
Thin Liquid Film ◽  
Disjoining Pressure ◽  
Dispersion Constant ◽  
Line Region ◽  
Fundamental Insight ◽  
First Time

The thickness and curvature profiles in the contact line region of a moving evaporating thin liquid film of pentane on a quartz substrate were measured for the thickness region, δ<2.5 μm. The critical region, δ<0.1 μm, was emphasized. The profiles were obtained using image-analyzing interferometry and an improved data analysis procedure. The precursor adsorbed film, the thickness, the curvature, and interfacial slope (variation of the local “apparent contact angle”) profiles were consistent with previous models based on interfacial concepts. Isothermal equilibrium conditions were used to verify the accuracy of the procedures and to evaluate the retarded dispersion constant in situ. The profiles give fundamental insight into the phenomena of phase change, pressure gradient, fluid flow, spreading, shear stress, and the physics of interfacial phenomena in the contact line region. The experimental results demonstrate explicitly, for the first time with microscopic detail, that the disjoining pressure controls fluid flow within an evaporating completely wetting thin curved film.

Precursor Film Formation Process Ahead Macroscopic Contact Line of Spreading Droplet on Smooth Substrate

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Ichiro Ueno ◽  
Kanji Hirose ◽  
Yusuke Kizaki ◽  
Yoshiaki Kisara ◽  
Yoshizumi Fukuhara
Keyword(s):  
Liquid Film ◽  
Contact Line ◽  
Formation Process ◽  
High Speed ◽  
Thin Liquid Film ◽  
Solid Substrate ◽  
Precursor Film ◽  
Boundary Line ◽  
Brewster Angle Microscopy ◽  
Droplet Spreading

The authors pay their special attention to formation process of wafer-thin liquid film, known as “precursor film,” ahead moving macroscopic contact line of a droplet spreading on a solid substrate. The spreading droplet on the solid substrate is accompanied with the movement of a visible boundary line so-called “macroscopic contact line.” Existing studies have indicated there exits a thin liquid film known as precursor film ahead the macroscopic contact line of the droplet. The present author’s group has dedicated their special effort to detect the formation process of the precursor film by applying a convectional laser interferometry and a high-speed camera, and to evaluate the spreading rate of the precursor film. In the present study, existing length of the precursor film at a very early stage of the droplet spreading is evaluated by applying a Brewster-angle microscopy as well as the interferometer. The authors extend their attention to the advancing process of the precursor film on inclined substrate.

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