A Theoretical Model of Striated Film-Rupture

1982 ◽  
Vol 104 (2) ◽  
pp. 164-167 ◽  
Author(s):  
C. Fall
Keyword(s):  
Thin Film ◽  
Theoretical Model ◽  
Viscous Fluid ◽  
Perturbation Analysis ◽  
Time Dependent ◽  
Linear Perturbation ◽  
Film Rupture ◽  
Gap Width ◽  
Theory And Experiment ◽  
Good Agreement

In general, when a thin film of viscous fluid ruptures in the diverging region of flow between a spreader (or roller) and a flat plate, the cavity formed is not uniform, but appears as adjacent air fingers separated by streamers of fluid. A time-dependent linear perturbation analysis is used to examine the nature of such striated film-rupture and, specifically, to predict the number of striations per unit width for varying minimum gap width and the parameter (ηU/T). Good agreement between theory and experiment is obtained.

A Theoretical Model of Striated Film-Rupture Applied to the Cylinder-Plane

1985 ◽  
Vol 107 (3) ◽  
pp. 419-422 ◽  
Author(s):  
C. Fall
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Perturbation Analysis ◽  
Reynolds Equation ◽  
Plane Geometry ◽  
Time Dependent ◽  
Linear Perturbation ◽  
Film Rupture ◽  
Successful Prediction

The author has previously presented a theoretical model of striated film-rupture consisting of a time-dependent linear perturbation analysis applied to the Reynolds equation. After review this model is applied to the cylinder-plane geometry for comparison with theoretical and experimental data due to Savage. Successful prediction of the number of striations for varying (ηU/T) and (R/h0) is achieved.

Surface Ribbing of a Thin Viscous Fluid Film Emerging From a Spreader or Roller

1978 ◽  
Vol 100 (4) ◽  
pp. 462-466 ◽  
Author(s):  
C. Fall
Keyword(s):  
Thin Film ◽  
Surface Tension ◽  
Viscous Fluid ◽  
Flat Plate ◽  
Perturbation Analysis ◽  
Linear Perturbation ◽  
Narrow Gap ◽  
Film Rupture ◽  
Characteristic Distance ◽  
Viscous Fluid Film

The thin film produced by the flow of a viscous fluid through a narrow gap between a spreader (or roller) and a flat plate is often subject to surface ribbing. A linear perturbation analysis, based upon lubrication theory, is used to examine the nature of this ribbed film and, specifically, to explain the large distances over which ribbing is observed to prevail. Taking into account the effects of both surface tension and gravity in smoothing out the film, the analysis predicts a characteristic distance from striated film-rupture to where a uniform film is formed.

A Three Dimensional Model for Generating the Texture in B-Scan Ultrasound Images

1983 ◽  
Vol 5 (3) ◽  
pp. 253-279 ◽  
Author(s):  
Mitchell M. Goodsitt ◽  
Ernest L. Madsen ◽  
James A. Zagzebski
Keyword(s):  
Three Dimensional ◽  
Time Dependent ◽  
Ultrasound Images ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Gray Scale ◽  
Receiver System ◽  
Gray Scale Image ◽  
Theory And Experiment ◽  
Good Agreement

A three-dimensional model for production of gray scale texture in ultrasound B-mode images is described. The model computes time-dependent echo signals resulting from scattering of acoustic pulses by particles randomly distributed in an attenuating medium and transforms these signals into a gray scale image. Specific transducer and pulser-receiver characteristics are accounted for, as well as the three-dimensional nature of the problem, without loss of computational efficiency. The model generates texture that closely corresponds to that found experimentally in ultrasound images of tissue-mimicking phantoms. The dependence of the texture upon the depth of the region that was scanned and on the characteristics of the transducer-receiver system were clearly demonstrated. Good agreement between theory and experiment was found for the texture in phantoms containing simulated spherical low-scatter tumors.

Fractal Analysis of Height Distributions of Anisotropic Rough Surfaces

Fractals ◽  
1998 ◽  
Vol 06 (01) ◽  
pp. 43-58 ◽  
Author(s):  
Denis Blackmore ◽  
Jack G. Zhou
Keyword(s):  
Distribution Function ◽  
Theoretical Model ◽  
Gaussian Function ◽  
General Distribution ◽  
Convergent Power Series ◽  
Fractal Parameters ◽  
Surface Profiles ◽  
Almost All ◽  
Theory And Experiment ◽  
Good Agreement

A general distribution function for the heights of anisotropic engineering surfaces is obtained by extending earlier work on surface profiles. The derivation starts from a functional description of surface heights that involves fractal quantities and is comprehensive enough to include almost all of the mathematical models for surface topography that have appeared in the literature. It is found that the distribution is in the form of a Gaussian function multiplied by a convergent power series, and the terms in the series depend in a fundamental way on the fractal parameters of the surface. This distribution is used to predict the dependence of bearing-area on fractal parameters, and is compared with other approaches to anisotropic surfaces in the literature. Two truncated approximate versions of the distribution function are introduced in order to test the theoretical model against experimentally obtained distributions of engineering surfaces; the results show good agreement between theory and experiment.

Parametric study of dissipative drift modes and their dynamic stabilization in a weakly ionized plasma

1979 ◽  
Vol 57 (5) ◽  
pp. 739-744 ◽  
Author(s):  
C. Boucher ◽  
S. Q. Mah ◽  
H. W. H. Van Andel ◽  
J. Teichmann
Keyword(s):  
Magnetic Field ◽  
Experimental Study ◽  
Theoretical Model ◽  
Dynamic Stabilization ◽  
Plasma Parameters ◽  
Azimuthal Magnetic Field ◽  
Weakly Ionized ◽  
Weakly Ionized Plasma ◽  
Theory And Experiment ◽  
Good Agreement

A detailed experimental study is made of dissipative drift modes in a weakly ionized plasma. The appearance of various modes as the plasma parameters are changed is compared with theory. A detailed study of the m = 3 mode in cylindrical geometry shows good agreement between experiment and a locally applied theoretical model. A method of dynamic stabilization using oscillating azimuthal magnetic field is studied and theory and experiment are compared for the m = 3 mode.

The Significance of Tread Element Flexibility to Thin Film Wet Traction

1975 ◽  
Vol 3 (4) ◽  
pp. 215-234 ◽  
Author(s):  
A. L. Browne ◽  
D. Whicker ◽  
S. M. Rohde
Keyword(s):  
Thin Film ◽  
Time Dependent ◽  
Lateral Expansion ◽  
Wheel Slip ◽  
Fluid Films ◽  
Thin Fluid

Abstract An analysis is presented for the action of individual tire tread elements on polished sections of pavement covered by thin fluid films. Tread element flexibility, wheel slip, and time-dependent loading are incorporated. The effect of the lateral expansion of tread elements on groove closure is also studied.

scholarly journals Stokes theory of thin-film rupture

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
D. Moreno-Boza ◽  
A. Martínez-Calvo ◽  
A. Sevilla
Keyword(s):  
Thin Film ◽  
Film Rupture

scholarly journals Moving Pearl Vortices in Thin-Film Superconductors

2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Vladimir Kogan ◽  
Norio Nakagawa
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Time Dependent ◽  
Superconducting Thin Film ◽  
Self Energy ◽  
London Equation ◽  
The Magnetic Field

The magnetic field hz of a moving Pearl vortex in a superconducting thin-film in (x,y) plane is studied with the help of the time-dependent London equation. It is found that for a vortex at the origin moving in +x direction, hz(x,y) is suppressed in front of the vortex, x>0, and enhanced behind (x<0). The distribution asymmetry is proportional to the velocity and to the conductivity of normal quasiparticles. The vortex self-energy and the interaction of two moving vortices are evaluated.

scholarly journals Adaptive Shell Spherical Reflector Actuated with PVDF-TrFE Thin Film Strain Actuators

Actuators ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 7
Author(s):  
Kainan Wang ◽  
Thomas Godfroid ◽  
Damien Robert ◽  
André Preumont
Keyword(s):  
Thin Film ◽  
Active Material ◽  
Quadratic Model ◽  
Influence Functions ◽  
Regularization Technique ◽  
Thin Polymer ◽  
Optical Modes ◽  
Electrostrictive Material ◽  
Ill Conditioning ◽  
Good Agreement

This paper discusses the design and manufacturing of a thin polymer spherical adaptive reflector of diameter D=200 mm, controlled by an array of 25 independent electrodes arranged in a keystone configuration actuating a thin film of PVDF-TrFE in d31-mode. The 5 μm layer of electrostrictive material is spray-coated. The results of the present study confirm that the active material can be modelled by a unidirectional quadratic model and that excellent properties can be achieved if the material is properly annealed. The experimental influence functions of the control electrodes are determined by a quasi-static harmonic technique; they are in good agreement with the numerical simulations and their better circular symmetry indicates a clear improvement in the manufacturing process, as compared to a previous study. The low order optical modes can be reconstructed by combining the 25 influence functions; a regularization technique is used to alleviate the ill-conditioning of the Jacobian and allow to approximate the optical modes with reasonable voltages.

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