An experimental investigation of stability and interfacial waves in co-current flow of two liquids

Charles, M. E.; Lilleleht, L. U.

doi:10.1017/s0022112065000691

Cited by 64 publications

(30 citation statements)

References 9 publications

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“…However, in qualitative agreement with the results in this paper, mixed laminar-turbulent regimes were observed simultaneously with interfacial instabilities by Hanratty & Engen (1957), Charles & Lilleleht (1965), and Kao & Park (1972) in channels and by Ludwieg & Hornung (1989) in boundary layers. For a thin-film configuration, it appears that laminar-turbulent transition in the main body of fluid may occur before or after initiation of interfacial instabilities; however only if the film viscosity and density differ considerably from the main-fluid parameters can the growth of turbulence be distinguished from the activity of interfacial modes.…”

Section: Discussionsupporting

confidence: 91%

“…We are not aware of any qualitative experimental data on the transitional-flow regimes in the boundary-layer/liquid film configuration which could be used for testing the present theory (but see below). One of the main conclusions of this work however, namely the significance of a strong competition between the two modes, seems to be in line with the known results for certain channel flows (see the experimental data in Charles & Lilleleht 1965;Kao & Park 1972, and the theory in Yantsios & Higgins 1988). …”

Section: Discussionsupporting

confidence: 88%

“…For the flow regimes chosen by Blennerhassett (1980) the TS waves appear at far larger Reynolds numbers and generally look much weaker than the interfacial mode. A competition between the two instabilities is more evident for the channel flows studied in Yantsios & Higgins (1988); it is also reflected in their comparisons with experiments by Charles & Lilleleht (1965), and Kao & Park (1972). For flow of the Lock (1954) type Akylas (1982) proposed a linear TS/interfacial mode resonance as a mechanism of water-wave generation.…”

Section: Introductionmentioning

confidence: 80%

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Instabilities in a high-Reynolds-number boundary layer on a film-coated surface

Timoshin

1997

J. Fluid Mech.

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A high-Reynolds-number asymptotic theory is developed for linear instability waves in a two-dimensional incompressible boundary layer on a flat surface coated with a thin film of a different fluid. The focus in this study is on the influence of the film flow on the lower-branch Tollmien-Schlighting waves, and also on the effect of boundary-layer/potential flow interaction on interfacial instabilities. Accordingly, the film thickness is assumed to be comparable to the thickness of a viscous sublayer in a three-tier asymptotic structure of lower-branch Tollmien-Schlichting disturbances. A fully nonlinear viscous/inviscid interaction formulation is derived, and computational and analytical solutions for small disturbances are obtained for both TollmienSchlichting and interfacial instabilities for a range of density and viscosity ratios of the fluids, and for various values of the surface tension coefficient and the Froude number. It is shown that the interfacial instability contains the fastest growing modes and an upper-branch neutral point within the chosen flow regime if the film viscosity is greater than the viscosity of the ambient fluid. For a less viscous film the theory predicts a lower neutral branch of shorter-scale interfacial waves. The film flow is found to have a strong effect on the Tollmien-Schlichting instability, the most dramatic outcome being a powerful destabilization of the flow due to a linear resonance between growing Tollmien-Schlichting and decaying capillary modes. Increased film viscosity also destabilizes Tollmien-Schlichting disturbances, with the maximum growth rate shifted towards shorter waves. Qualitative and quantitative comparisons are made with experimental observations by Ludwieg & Hornung (1989).

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 80%

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Instabilities in a high-Reynolds-number boundary layer on a film-coated surface

Timoshin

1997

J. Fluid Mech.

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“…The stability problem for these flow configurations has been studied theoretically by Renardy (1985), Hooper and Boyd (1987), , Hooper (1989) and Tilley et al (1994), who all find shear mode instability if the (bulk average) liquid flow rate is sufficiently large. Experimental observations of unstable shear modes in two-layer channel flow have been reported by Charles and Lilleleht (1965), Kao and Park (1972) and Hame and Muller (1975). In a somewhat different context, i.e.…”

Section: Shear Mode Instabiliomentioning

confidence: 78%

Classification of instabilities in parallel two-phase flow

Boomkamp

1996

International Journal of Multiphase Flow

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Abstract--There is extensive literature on the stability of parallel two-phase flow, both in the context of liquid-liquid as well as gas-liquid flow. Aimed at making this literature more transparent, this paper presents a classification scheme for the various instabilities arising in parallel two-phase flow..To achieve such a classification, the equation governing the rate of change of the kinetic energy of the disturbances is evaluated for relevant values of the physical parameters. This shows the existence of five different ways of energy transfer from the primary to the disturbed flow, which have their origin in density stratification, velocity profile curvature, viscosity stratification or shear effects. Each class is discussed on the basis of references covering the developments over the last 35 years. © 1997 Elsevier Science Ltd.

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“…Now, focusing on the special case of co-courant flow of two liquids in plane Poiseuille configuration, literature provides less papers than for the cylindrical case. Charles & Lilleleht [4] determined the laminar-turbulent transitions for both phases experimentally. a e-mail : ahmad.ahmad@univ-brest.fr Notably, the transition to turbulence in the water phase occurred at a higher Reynolds number in presence of a laminar oil layer provided the input water-to-oil ratio was relatively high, while the transition in the oil phase took place at a lower Reynolds number in the presence of a turbulent water layer.…”

Section: Introductionmentioning

confidence: 99%

Stability of Water Lubricated Flow of Yield Stress Fluid in Sloping Pipe

Ahmad

Nsom

Decruppe³

2010

EPJ Web of Conferences

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Abstract.To facilitate the transport of viscous crudes in a pipe, an immiscible lubricating liquid, usually water, is added. In such configuration, the water migrates into the regions of high shear at the pipe wall where it lubricates the flow. The pumping pressures being balanced by wall shear stresses in the water, the flow therefore requires pressures comparable to pumping water alone, at the same total throughput [1]. So significant savings in pumping power can be derived from this process provided that it is well monitored. Indeed, instabilities usually take place at the oil/water interface and they constitute an important source of energy dissipation. Precisely, a core annular flow is known to undergo a long-wave instability of capillary type, modified by shear occuring at low Reynolds. Above a given critical Reynolds number, the flow is unstable to shorter waves which leads to an emulsification system of water droplets in oil. In present work, an experimental study of the stability of sloping plane Poiseuille flow of well characterized viscoplastic mineral oils lubricated by water was performed. The investigation was carried out by means of image analysis based on spatiotemporal diagrams (STD). Notably indicated are the effects of bed slope, flow rates ratio and oil rheology on flow stability.

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An experimental investigation of stability and interfacial waves in co-current flow of two liquids

Cited by 64 publications

References 9 publications

Instabilities in a high-Reynolds-number boundary layer on a film-coated surface

Instabilities in a high-Reynolds-number boundary layer on a film-coated surface

Classification of instabilities in parallel two-phase flow

Stability of Water Lubricated Flow of Yield Stress Fluid in Sloping Pipe

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