Viscous Liquid Films in Nonradial Rotating Pipes[1]

1980 ◽  
Vol 102 (2) ◽  
pp. 231-235
Author(s):  
J. T. Dakin
Keyword(s):  
Liquid Film ◽  
Centrifugal Force ◽  
Radial Direction ◽  
Thin Liquid Film ◽  
Film Surface ◽  
Liquid Films ◽  
Surface Shape ◽  
Pipe Axis ◽  
Viscous Forces ◽  
Secondary Motion

The dynamics of a thin liquid film flowing through a rotating pipe are studied. The flow is assumed to be fully developed and dominated by viscous forces. The fluid is drawn along the pipe by the centrifugal force. The pipe is tilted with respect to the radial direction so that the centrifugal force has a component perpendicular to the pipe axis. An approximate dynamic model is developed which describes the film surface shape, and which includes the effects of the Coriolis-induced secondary motion. Several simple, interesting solutions are presented.

The Influence of Evaporation in Shear-Driven Liquid Film on Heat Removal From Local Heater

2006 ◽  
Author(s):  
Elizaveta Gatapova ◽  
Oleg Kabov
Keyword(s):  
Liquid Film ◽  
Thin Liquid Film ◽  
Heat Removal ◽  
Film Surface ◽  
Numerical Data ◽  
High Heat ◽  
Liquid Films ◽  
High Heat Flux ◽  
Maximal Surface ◽  
High Heat Transfer

The present work focuses upon shear-driven liquid film evaporative cooling of high heat flux local heater. Thin evaporating liquid films may provide very high heat transfer rates and can be used for cooling of high power microelectronic systems. Thermocapillary convection in a liquid film falling down a locally heated substrate has recently been extensively studied. However, non-uniform heating effects remain only partially understood for shear-driven liquid films. The combined effects of evaporation, thermocapillarity and gas dynamics as well as formation of microscopic adsorbed film have not been studied. The effect of evaporation on heat and mass transfer for 2D joint flow of a liquid film and gas is theoretically and numerically investigated. The convective terms in the energy equations are taken into account. The calculations reveal that evaporation from film surface essential influences on heat removal from local heater. It is shown that the thermal boundary layer plays significant role for cooling local heater by evaporating thin liquid film. Measured by an infrared scanner temperature distribution at the film surface is compared with numerical data. Calculations satisfactorily describe the maximal surface temperature value.

scholarly journals Stability of an evaporating thin liquid film

2007 ◽  
Vol 584 ◽  
pp. 157-183 ◽  
Author(s):  
OLEG E. SHKLYAEV ◽  
ELIOT FRIED
Keyword(s):  
Liquid Film ◽  
Thin Liquid Film ◽  
Film Surface ◽  
Liquid Films ◽  
Langmuir Equation ◽  
Van Der Waals Interactions ◽  
Time Dependent ◽  
Configurational Forces ◽  
Effective Pressure ◽  
Molten Metals

We use a newly developed set of interface conditions to revisit the problem of an evaporating thin liquid film. In particular, instead of the conventional Hertz–Knudsen–Langmuir equation for the evaporation mass flux, we impose a more general equation expressing the balance of configurational momentum. This balance, which supplements the conventional conditions enforcing the balances of mass, momentum and energy on the film surface, arises from a consideration of configurational forces within a thermodynamical framework. We study the influence of two newly introduced terms on the evolution of the liquid film. One of these terms accounts for the transport of energy within the liquid–vapour interface. The other term, which we refer to as the effective pressure, accounts for vapour recoil. Both new terms are found to be stabilizing. Furthermore, the effective pressure is found to affect a time-dependent base state of the evaporating film and to be an important factor in applications involving liquid films with thicknesses of one or two monolayers. Specifically, we demonstrate that consideration of the effective pressure makes it possible to observe the influence of the van der Waals interactions on film evolution close to the instant of rupture. Dimensional considerations indicate that one of the most significant influences of these effects occurs for molten metals.

The Dynamics of Thin Liquid Films in Rotating Tubes: Approximate Analysis

1978 ◽  
Vol 100 (2) ◽  
pp. 187-193 ◽  
Author(s):  
J. T. Dakin ◽  
Ronald M. C. So
Keyword(s):  
Thin Liquid Film ◽  
Axial Flow ◽  
Direct Consequence ◽  
Liquid Films ◽  
Approximate Theory ◽  
Viscous Effects ◽  
Pipe Axis ◽  
Plane Normal ◽  
Secondary Motion ◽  
Set Up

The dynamics of a thin liquid film flowing through a pipe rotating about an axis perpendicular to the pipe axis are studied. Static pressure is assumed constant along the pipe and the axial flow of the film is a direct consequence of the pull of the centrifugal force. The film is pushed to one side of the pipe by a Coriolis force which is nonconservative. As a result, a secondary motion is set up in the plane normal to the pipe axis. An approximate set of equations governing the secondary flow is analyzed through an integral technique for the case of a laminar film dominated by viscous effects. A visualization experiment is carried out and the approximate theory is found to compare favorably with the qualitative observations.

scholarly journals Visualization of Surface Acoustic Waves in Thin Liquid Films

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
R. W. Rambach ◽  
J. Taiber ◽  
C. M. L. Scheck ◽  
C. Meyer ◽  
J. Reboud ◽  
...  
Keyword(s):  
Liquid Film ◽  
Acoustic Waves ◽  
Low Cost ◽  
Thin Liquid Film ◽  
Surface Acoustic Waves ◽  
Liquid Films ◽  
Theoretical Description ◽  
Propagation Path ◽  
Microfluidic Channels ◽  
Potential Applications

Abstract We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfluidic channels. It also enables low-cost characterisation of IDT designs thereby allowing the determination of anisotropy and orientation of the piezoelectric substrate without the requirement for sophisticated and expensive equipment. Here, we show that the optical visibility of the sound path critically depends on the physical properties of the liquid film and identify heptane and methanol as most contrast rich solvents for visualization of SAW. We also provide a detailed theoretical description of this effect.

Deformation Characteristics of the Ultrathin Liquid Film Surface Considering the Effects of Polar Endgroups

2007 ◽  
Author(s):  
Shigehisa Fukui ◽  
Soichi Shimizu ◽  
Kiyomi Yamane ◽  
Hiroshige Matsuoka
Keyword(s):  
Liquid Film ◽  
Thin Liquid Film ◽  
Film Surface ◽  
Wave Theory ◽  
Initial Boundary ◽  
Surface Forces ◽  
Deformation Characteristics ◽  
Long Wave ◽  
Vdw Force ◽  
Time Evolution Equation

To examine deformations of ultra-thin but continuum liquid film, the long wave theory was employed. The long wave theory uses the time-evolution equation for the shape and deformation of the thin liquid film and includes the surface tensions and surface forces such as the van der Waals (vdW) force. By numerically solving the time-dependent long wave equation, deformations of the ultra-thin lubricant film considering the vdW pressure with initial/boundary configurations of the liquid surfaces were obtained.

scholarly journals On the origin of the circular hydraulic jump in a thin liquid film

2018 ◽  
Vol 851 ◽  
Author(s):  
Rajesh K. Bhagat ◽  
N. K. Jha ◽  
P. F. Linden ◽  
D. Ian Wilson
Keyword(s):  
Thin Film ◽  
Surface Tension ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Capillary Waves ◽  
Hydraulic Jumps ◽  
Planar Surface ◽  
Normal Impact ◽  
Viscous Forces

This study explores the formation of circular thin-film hydraulic jumps caused by the normal impact of a jet on an infinite planar surface. For more than a century, it has been believed that all hydraulic jumps are created due to gravity. However, we show that these thin-film hydraulic jumps result from energy loss due to surface tension and viscous forces alone. We show that, at the jump, surface tension and viscous forces balance the momentum in the liquid film and gravity plays no significant role. Experiments show no dependence on the orientation of the surface and a scaling relation balancing viscous forces and surface tension collapses the experimental data. A theoretical analysis shows that the downstream transport of surface energy is the previously neglected critical ingredient in these flows, and that capillary waves play the role of gravity waves in a traditional jump in demarcating the transition from the supercritical to subcritical flow associated with these jumps.

Stability Analysis of Ultra-thin Liquid Film Surface : Influence of Boundary with Nanometer Spacing

2004 ◽  
Vol 2004.42 (0) ◽  
pp. 409-410
Author(s):  
Daigou AKASAKA ◽  
Kazuya YORINO ◽  
Hiroshige MATSUOKA ◽  
Shigehisa FUKUI
Keyword(s):  
Stability Analysis ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Film Surface

Temporal Effect and Transient Simulation of Thin Liquid Film in Micro Channels

2013 ◽  
Author(s):  
Yu-Yan Jiang ◽  
Da-Wei Tang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Film ◽  
Flow Boiling ◽  
Thin Liquid Film ◽  
Liquid Films ◽  
Transient Simulation ◽  
Governing Equations ◽  
Flash Evaporation ◽  
Micro Channels

The evaporation and heat transfer of thin liquid film are crucial factors affecting on the heat transfer performance of boiling bubbles or slugs. For boiling in micro-channels, the flash evaporation of the liquid film may give rise to boiling instability, and the dry-out of the film leads to serious deterioration of the heat transport. The thin liquid film has multi-scale transitions, and hence the phase change and fluid dynamics need to be solved by special governing equations and numerical algorithm. The numerical studies to date have solved the steady state distribution of the film, but the difficulty consists in the transient simulation of time-variant liquid films. In the present study, unsteady form governing equations are developed. With inclusion of the temporal terms, we conducted transient simulations for flat liquid films formed during the flow boiling in micro-channels. The model predicts the developing of drying spot during growth of elongated bubbles. The results show that the film thickness and distribution change quickly in a growth period, which are functions of the heat flux, mass flow rate and the other parameters. The quantitative assessment of these effects helps to clarify the mechanism of boiling instability and the conditions for the occurrence of critical heat flux (CHF). The simulation needs special numerical scheme for time marching and stabilization treatment for the nonlinear terms, where the numerical accuracy and the significance of the temporal effects are also discussed.

413 The Washboard Effect of Ultra-thin Liquid Film Surface : Fundamental Characteristics Considering Slider Dynamics

2006 ◽  
Vol 2006 (0) ◽  
pp. 149-150
Author(s):  
Hiroshi OTA ◽  
Yuka OSAKI ◽  
Hiroshige MATSUOKA ◽  
Shigehisa FUKUI
Keyword(s):  
Liquid Film ◽  
Thin Liquid Film ◽  
Film Surface
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