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.

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.

Precursor Film Formation of Spreading Droplet

2010 ◽  
Author(s):  
Ichiro Ueno ◽  
Kanji Hirose ◽  
Yusuke Kizaki
Keyword(s):  
Formation Process ◽  
High Speed ◽  
Molecular Diffusion ◽  
Early Stage ◽  
Thin Liquid Film ◽  
Solid Substrate ◽  
Precursor Film ◽  
Boundary Line ◽  
Brewster Angle Microscopy ◽  
Droplet Spreading

We focus on a formation process of a quite thin liquid film, known as ‘precursor film,’ ahead a droplet spreading on a smooth solid substrate. The spreading droplet on the solid substrate is accompanied with a movement of a visible boundary line so-called ‘macroscopic contact line.’ Existing studies have indicated there exist two major regions of the precursor film, that is, a region dominated by the fluid dynamics, and a region dominated by the molecular diffusion. Our group has dedicated our 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, the 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. We extend our attention to the advancing process of the precursor film on inclined substrate.

Detection of Advancing Edge and Existing Length of Precursor Film Ahead Macroscopic Contact Line of Droplet Spreading on Solid Substrate

2008 ◽  
Author(s):  
Ichiro Ueno
Keyword(s):  
Contact Line ◽  
High Speed ◽  
Thin Liquid Film ◽  
Experimental Studies ◽  
Laser Interferometry ◽  
Spreading Rate ◽  
Solid Substrate ◽  
Precursor Film ◽  
Boundary Line ◽  
Droplet Spreading

The author introduces a series of experimental studies on a simple but complex wetting process; a droplet spreads 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 advancing edge 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.

Droplet spreading and absorption on rough, permeable substrates

2015 ◽  
Vol 784 ◽  
pp. 465-486 ◽  
Author(s):  
Leonardo Espín ◽  
Satish Kumar
Keyword(s):  
Surface Roughness ◽  
Contact Line ◽  
Nonlinear Evolution ◽  
Precursor Film ◽  
Radial Coordinate ◽  
Droplet Spreading ◽  
Liquid Spreading ◽  
Line Region ◽  
Influence Of Substrate ◽  
Contact Line Pinning

Wetting of permeable substrates by liquids is an important phenomenon in many natural and industrial processes. Substrate heterogeneities may significantly alter liquid spreading and interface shapes, which in turn may alter liquid imbibition. A new lubrication-theory-based model for droplet spreading on permeable substrates that incorporates surface roughness is developed in this work. The substrate is assumed to be saturated with liquid, and the contact-line region is described by including a precursor film and disjoining pressure. A novel boundary condition for liquid imbibition is applied that eliminates the need for a droplet-thickness-dependent substrate permeability that has been employed in previous models. A nonlinear evolution equation describing droplet height as a function of time and the radial coordinate is derived and then numerically solved to characterize the influence of substrate permeability and roughness on axisymmetric droplet spreading. Because it incorporates surface roughness, the new model is able to describe the contact-line pinning that has been observed in experiments but not captured by previous models.

Evaporation of Thin Film of Polar Liquid in Presence of Soluble Surfactant

2015 ◽  
Vol 1105 ◽  
pp. 105-109 ◽  
Author(s):  
Varvara Yu. Gordeeva ◽  
Andrey V. Lyushnin
Keyword(s):  
Liquid Film ◽  
Stokes Equations ◽  
Thin Liquid Film ◽  
Specific Interaction ◽  
Surface Concentration ◽  
Double Electric Layer ◽  
Solid Substrate ◽  
Polar Liquid ◽  
Navier Stokes ◽  
Navier Stokes Equations

Evaporation of a thin layer of a polar liquid (water) having a free surface and located on a solid substrate is investigated. A surfactant is solved in the liquid film. The surface tension is a linear function of the surface concentration of the surfactant. The surface energy of the solid-liquid interface is a nonmonotonic function of the layer thickness and is the sum of the Van der Waals interaction and the specific interaction of the double electric layer on the interface. The effect of the solvable surfactant on the dynamics of the propagation of the evaporation front in the thin liquid film is analyzed in the long-wave approximation in the system of Navier-Stokes equations.

Three-Dimensional Shear Driven Thin Liquid Film in a Duct

2006 ◽  
Author(s):  
H. Lan ◽  
M. Friedrich ◽  
B. F. Armaly ◽  
J. A. Drallmeier
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Flow Rate ◽  
High Speed ◽  
Volume Flow Rate ◽  
Incident Light ◽  
Thin Liquid Film ◽  
Air Flow ◽  
Three Dimensional ◽  
Vof Model

Measurements and predictions of three-dimensional shear driven thin liquid films by turbulent air flow in a duct are reported. FLUENT - CFD code is used to perform the numerical simulations and the Reynolds Averaged Navier-Stokes and continuity equations along with the Volume of Fluid (VOF) model and the realizable k-ε turbulence model are implemented for this task. Film thickness and width are reported as a function of air flow rate, liquid film volume flow rate and surface tension, and a comparison with preliminary measured results is made. The thickness of the shear driven liquid film is measured using an interferometric technique that makes use of the phase shift between the reflection of incident light from the top and bottom surfaces of the thin liquid film. The spatial resolution is determined based on the spot size of the incident light, which for the current configuration of the transmitting optics is approximately 10 microns. The resulting fringe pattern is imaged using a high-speed imaging camera operating at 2000 frames per second. The technique has proved successful in measuring thickness between 100 and 900 microns in these shear driven films. Simulation results reveal that higher gas flow velocity decreases the film thickness but increases its width, while higher liquid film flow rate increases the film thickness and increases its width. Reasonable comparison appears to exist between preliminary measured and simulated results.

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

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.

Sign in / Sign up

Export Citation Format

Share Document