Primary instability of a visco-plastic film down an inclined plane: experimental study

The main objective of this work is to study experimentally the primary instability of non-Newtonian film flows down an inclined plane. We focus on low-concentration shear-thinning aqueous solutions obeying the Carreau law. The experimental study essentially consists of measuring wavelengths in marginal conditions, which yields the primary stability threshold for a given slope. The experimental results for neutral curves presented in the $(Re,f_{c})$ and $(Re,k)$ planes (where $f_{c}$ is the driving frequency, $k$ is the wavenumber and $Re$ is the Reynolds number) are in good agreement with the numerical results obtained by a resolution of the generalized Orr–Sommerfeld equation. The long-wave asymptotic extension of our results is consistent with former theoretical predictions of the critical Reynolds number. This is the first experimental evidence of the destabilizing effect of the shear-thinning behaviour in comparison with the Newtonian case: the critical Reynolds number is smaller, and the ratio between the critical wave celerity and the flow velocity at the free surface is larger.

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An Accurate Low Dimension Model for the Waves on Thin Layer Fluid Flowing Down an Inclined Plane

Journal of Applied Mechanics ◽

10.1115/1.3114968 ◽

2009 ◽

Vol 76 (6) ◽

Author(s):

H. Ait Abderrahmane ◽

G. H. Vatistas

Keyword(s):

Film Flow ◽

Equation Model ◽

Surface Velocity ◽

Inclined Plane ◽

Linear Pulse ◽

Pulse Structure ◽

The Waves ◽

Theoretical Results ◽

Primary Instability ◽

Good Agreement

This technical brief deals with the surface instability mode of a liquid film flowing down an inclined plane. A four-equation model that describes the development of the film depth, the flow rate, the free-surface velocity, and the wall shear stress is proposed. The obtained results were found to be in very good agreement with experimental and theoretical results of Liu et al. (1993, “Measurements of the Primary Instability of Film Flow,” J. Fluid Mech., 250, pp. 69–101) and Brevdo et al. (1999, “Linear Pulse Structure and Signalling in Film Flow on an Inclined Plane,” J. Fluid Mech., 396, pp. 37–71).

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Experimental study of collisional granular flows down an inclined plane

Journal of Fluid Mechanics ◽

10.1017/s0022112099006461 ◽

1999 ◽

Vol 400 ◽

pp. 199-227 ◽

Cited By ~ 105

Author(s):

EMMANUEL AZANZA ◽

FRANÇOIS CHEVOIR ◽

PASCAL MOUCHERONT

Keyword(s):

Experimental Study ◽

Kinetic Theory ◽

Granular Material ◽

Solid Fraction ◽

Particle Flux ◽

Inclined Plane ◽

Mean Velocity ◽

Hydrodynamic Description ◽

Rough Plane ◽

Complete Measurement

The collisional flow of a slightly inelastic granular material down a rough inclined plane is usually described by kinetic theories. We present an experimental study aimed at analysing the assumptions and the quantitative predictions of such theories. A two-dimensional channel coupled to a model granular material and image analysis allow detailed and complete measurement of the kinematics and structure of the flows. We determine the range of inclination and particle flux for which the flow is stationary and uniform. The characteristic profiles of solid fraction, mean velocity and granular temperature are systematically measured. Both the true collisional and the dilute kinetic regimes are examined. We show that a quasi-hydrodynamic description of these regimes seems relevant, and that the pressure and the viscosity terms are in good qualitative agreement with the prediction of the kinetic theory. The profiles are well described by the kinetic theory near the top of the flow, at low solid fraction. Conversely there are large discrepancies near the rough plane, where the material is structured in layers.

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Experimental Study of an Inclined-Plane Electrostatic Separator

Proceedings of the Third International Symposium on Materials and Sustainable Development ◽

10.1007/978-3-319-89707-3_50 ◽

2018 ◽

pp. 439-450 ◽

Cited By ~ 1

Author(s):

A. Nadjem ◽

M. Kachi ◽

K. Rouagdia ◽

M. Remadnia

Keyword(s):

Experimental Study ◽

Inclined Plane ◽

Electrostatic Separator

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An Experimental Study on the Performance of a Cross-Flow-Type, Indirect Evaporative Cooler Made of Paper/Plastic Film

Korean Journal of Air-Conditioning and Refrigeration Engineering ◽

10.6110/kjacr.2015.27.9.475 ◽

2015 ◽

Vol 27 (9) ◽

pp. 475-483 ◽

Cited By ~ 3

Author(s):

Mi-Hye Kwon ◽

Min-Geon Go ◽

Nae-Hyun Kim

Keyword(s):

Experimental Study ◽

Cross Flow ◽

Plastic Film ◽

Flow Type ◽

Evaporative Cooler

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Experimental study on the restoration from a tilt-azimuth series for improvement in resolution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013955x ◽

1995 ◽

Vol 53 ◽

pp. 636-637

Author(s):

Norio Baba ◽

Norihiko Ichise ◽

Syunya Watanabe

Keyword(s):

Experimental Study ◽

Spherical Aberration ◽

Incident Beam ◽

Optical Parameters ◽

Beam Tilting ◽

Illumination Method ◽

Restoration Method ◽

Illumination Mode

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.

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