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.

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.

scholarly journals Analysis of Hydrodynamics and Heat Transfer in a Thin Liquid Film Flowing Over a Rotating Disk by the Integral Method

2005 ◽  
Vol 128 (3) ◽  
pp. 217-225 ◽  
Author(s):  
S. Basu ◽  
B. M. Cetegen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Rotating Disk ◽  
Disk Surface ◽  
Experimental Results ◽  
Rotation Rates

An integral analysis of hydrodynamics and heat transfer in a thin liquid film flowing over a rotating disk surface is presented for both constant temperature and constant heat flux boundary conditions. The model is found to capture the correct trends of the liquid film thickness variation over the disk surface and compare reasonably well with experimental results over the range of Reynolds and Rossby numbers covering both inertia and rotation dominated regimes. Nusselt number variation over the disk surface shows two types of behavior. At low rotation rates, the Nusselt number exhibits a radial decay with Nusselt number magnitudes increasing with higher inlet Reynolds number for both constant wall temperature and heat flux cases. At high rotation rates, the Nusselt number profiles exhibit a peak whose location advances radially outward with increasing film Reynolds number or inertia. The results also compare favorably with the full numerical simulation results from an earlier study as well as with the reported experimental results.

A Numerical Study on Motion of a Sphere Coated With a Thin Liquid Film at Intermediate Reynolds Numbers

1997 ◽  
Vol 119 (2) ◽  
pp. 397-403 ◽  
Author(s):  
S. Kawano ◽  
H. Hashimoto
Keyword(s):  
Reynolds Number ◽  
Liquid Film ◽  
Drag Coefficient ◽  
Flow Pattern ◽  
Numerical Study ◽  
Thin Liquid Film ◽  
Strong Dependence ◽  
Reynolds Numbers ◽  
Rigid Sphere ◽  
Flow Past A Sphere

The steady viscous flow past a sphere coated with a thin liquid film at low and intermediate Reynolds numbers (Re ≤ 200) was investigated numerically. The influences of fluid physical properties, film thickness, and Reynolds number on the flow pattern were clarified. Temperature field around the compound drop was also analyzed. The strong dependence of flow pattern on the characteristics of heat transfer was recognized. The empirical equation of the drag coefficient for the compound drop was proposed. Furthermore, the explicit adaptability of the drag coefficient equation for a gas bubble, a liquid drop, and a rigid, sphere in the range of Reynolds number Re ≤ 1000 was confirmed.

CFD Modeling of a Thin Liquid Film Flow over Horizontal Spinning Disk

2014 ◽  
Vol 625 ◽  
pp. 517-521
Author(s):  
Nurhazwani Yusoff Azudin ◽  
Mohd Fadhil Majnis ◽  
Ahmad Abdul Latif ◽  
Syamsul Rizal Abd Shukor
Keyword(s):  
Liquid Film ◽  
Cfd Simulation ◽  
Film Flow ◽  
Mechanistic Model ◽  
Thin Liquid Film ◽  
Process Intensification ◽  
Cfd Modeling ◽  
Spinning Disk ◽  
Vof Model ◽  
Liquid Film Flow

A thin liquid film flow over horizontal spinning disk under influence of centrifugal field is one of the implementation and method in process intensification. Hydrodynamic studies and development of mechanistic model is desired to describe this film flow behaviours. CFD software package, Fluent® 6.3 was used to simulate a multiphase volume of fraction (VOF) model of this flow. Then, experiments were carried out in a spinning disk test rig with variable speed of spinning and results were compared with CFD simulation. The result obtained have showed that CFD model for thin liquid film thickness was in satisfactory agreement with the experimental results with R2 = 0.841 to 0.857.

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.

The development of nonlinear waves on the surface of a horizontally rotating thin liquid film

1987 ◽  
Vol 184 ◽  
pp. 357-379 ◽  
Author(s):  
D. J. Needham ◽  
J. H. Merkin
Keyword(s):  
Liquid Film ◽  
Nonlinear Waves ◽  
Thin Liquid Film ◽  
Asymptotic Structure ◽  
Spinning Disk

We consider the axisymmetric thin liquid film formed on a horizontally spinning disk. The asymptotic structure of the steady film is obtained, after which a theory is developed to describe the evolution of localized disturbances imposed upon the steady film. It is shown that this can lead to the propagation of large gradients in the film. Moreover, it is found that under certain conditions the steady film can become unstable.

scholarly journals A Study on the Mixing Characteristics of Thin Liquid Film Flows over Horizontal Spinning Disk Surface

2016 ◽  
Vol 148 ◽  
pp. 957-962 ◽  
Author(s):  
Mohd Fadhil Majnis ◽  
Nurhazwani Yusoff Azudin ◽  
Syamsul Rizal Abd Shukor ◽  
Abdul Latif Ahmad
Keyword(s):  
Liquid Film ◽  
Thin Liquid Film ◽  
Disk Surface ◽  
Spinning Disk ◽  
Mixing Characteristics ◽  
Film Flows

scholarly journals Droplet impact on a thin liquid film: anatomy of the splash

2016 ◽  
Vol 802 ◽  
pp. 775-805 ◽  
Author(s):  
Christophe Josserand ◽  
Pascal Ray ◽  
Stéphane Zaleski
Keyword(s):  
Reynolds Number ◽  
Liquid Film ◽  
Numerical Simulations ◽  
Thin Liquid Film ◽  
Droplet Impact ◽  
The Other ◽  
Dimensionless Number ◽  
Scaling Analysis ◽  
The Impact ◽  
Short Times

We investigate the dynamics of drop impact on a thin liquid film at short times in order to identify the mechanisms of splash formation. Using numerical simulations and scaling analysis, we show that it depends both on the inertial dynamics of the liquid and the cushioning of the gas. Two asymptotic regimes are identified, characterized by a new dimensionless number $J$: when the gas cushioning is weak, the jet is formed after a sequence of bubbles are entrapped and the jet speed is mostly selected by the Reynolds number of the impact. On the other hand, when the air cushioning is important, the lubrication of the gas beneath the drop and the liquid film controls the dynamics, leading to a single bubble entrapment and a weaker jet velocity.

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