Static and Dynamic Optical Analysis of Micro Wrinkle Formation on a Liquid Surface

A spatially periodic voltage was used to create a dielectrophoresis induced periodic micro wrinkle deformation on the surface of a liquid film. Optical Coherence Tomography provided the equilibrium wrinkle profile at submicron accuracy. The dynamic wrinkle amplitude was derived from optical diffraction analysis during sub-millisecond wrinkle formation and decay, after abruptly increasing or reducing the voltage, respectively. The decay time constant closely followed the film thickness dependence expected for surface tension driven viscous levelling. Modelling of the system using numerical solution of the Stokes flow equations with electrostatic forcing predicted that wrinkle formation was faster than decay, in accord with observations.

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Optical Analysis of Ball Bearing Starvation

Journal of Lubrication Technology ◽

10.1115/1.3451591 ◽

1971 ◽

Vol 93 (3) ◽

pp. 349-361 ◽

Cited By ~ 172

Author(s):

L. D. Wedeven ◽

D. Evans ◽

A. Cameron

Keyword(s):

Film Thickness ◽

Ball Bearing ◽

Point Contact ◽

Experimental Measurements ◽

Line Contact ◽

Optical Analysis ◽

Grease Lubrication ◽

Theoretical Predictions ◽

Pressure Stress ◽

Starvation Conditions

Elastohydrodynamic oil film measurements for rolling point contact under starvation conditions are obtained using optical interferometry. The experimental measurements present a reasonably clear picture of the starvation phenomenon and are shown to agree with theoretical predictions. Starvation inhibits the generation of pressure and, therefore, reduces film thickness. It also causes the overall pressure, stress, and elastic deformation to become more Hertzian. Additional experiments using interferometry illustrate: the cavitation pattern, lubricant entrapment, grease lubrication, ball spin, and edge effects in line contact.

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The gas-liquid surface of the penetrable sphere model. II

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1978.0009 ◽

1978 ◽

Vol 358 (1694) ◽

pp. 267-280 ◽

Cited By ~ 5

Keyword(s):

Surface Tension ◽

Correlation Function ◽

Liquid Surface ◽

Mean Field ◽

Field Approximation ◽

Mean Field Approximation ◽

Intermolecular Potential ◽

Direct Correlation Function ◽

Sphere Model ◽

One Dimensional

The direct correlation function between two points in the gas-liquid surface of the penetrable sphere model is obtained in a mean-field approximation. This function is used to show explicitly that three apparently different ways of calculating the surface tension all lead to the same result. They are (1) from the virial of the intermolecular potential, (2) from the direct correlation function, and (3) from the energy density. The equality of (1) and (2) is shown analytically at all temperatures 0 < T < T c where T c is the critical temperature; the equality of (2) and (3) is shown analytically for T ≈ T c , and by numerical integration at lower temperatures. The equality of (2) and (3) is shown analytically at all temperatures for a one-dimensional potential.

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Trickle/pulse flow regime transition in downflow packed tower involving foaming liquids

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq111201011s ◽

2012 ◽

Vol 18 (3) ◽

pp. 349-359

Author(s):

Vijay Sodhi

Keyword(s):

Surface Tension ◽

Liquid Flow ◽

Liquid Surface ◽

Regime Transition ◽

Pulse Flow ◽

Packed Tower ◽

Flow Rates ◽

Transition Boundary ◽

Liquid Surface Tension ◽

Pulsing Flow

The most of past studies in foaming trickle bed reactors aimed at the improvement of efficiency and operational parameters leads to high economic advantages. Conventionally most of the industries rely on frequently used gas continuous flow (GCF) where operational output is satisfactory but not yields efficiently as in pulsing flow (PF) and foaming pulsing flow (FPF). Hydrodynamic characteristics like regime transitions are significantly influenced by foaming nature of liquid as well as gas and liquid flow rates. This study?s aim was to demonstrate experimentally the effects of liquid flow rate, gas flow rates and liquid surface tension on regime transition. These parameters were analyzed for the air-aqueous Sodium Lauryl Sulphate and air-water systems. More than 240 experiments were done to obtain the transition boundary for trickle flow (GCF) to foaming pulsing flow (PF/FPF) by use excessive foaming 15-60 ppm surfactant compositions. The trickle to pulse flow transition appeared at lower gas and liquid flow rates with decrease in liquid surface tension. All experimental data had been collected and drawn in the form of four different transitional plots which are compared and drawn by using flow coordinates proposed by different researchers. A prominent decrease in dynamic liquid saturation was observed especially during regime transitional change. The reactor two phase pressure evident a sharp rise to verify the regime transition shift from GCF to PF/FPF. Present study reveals, the regime transition boundary significantly influenced by any change in hydrodynamic as well as physiochemical properties including surface tension.

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