Pearl and mushroom instability patterns in two miscible fluids' core annular flows

D'olce, Marguerite; Martin, James E.; Rakotomalala, N.; Salin, D.; Talon, Laurent

doi:10.1063/1.2838582

Cited by 58 publications

(24 citation statements)

References 21 publications

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“…Sahu et al 37 showed that the above system becomes absolutely unstable for a certain range of parameters and have indicated the region of absolute and convective instabilities in the Reynolds number and viscosity ratio space. There are also several investigations 29,30,[38][39][40][41][42][43][44][45][46][47][48] not relevant to the present study (but worth mentioning in the present context) that deals with stability characteristics of viscosity stratified flows in rigid channels/pipes, involving the displacement of one fluid by another. The interesting features and the type of instabilities displayed by these flow systems with boundaries as either rigid walls or rigid circular pipes suggest that it is worth analyzing the analogous flow systems in configurations with velocity slip at the boundaries.…”

Section: Introductionmentioning

confidence: 99%

Double-diffusive two-fluid flow in a slippery channel: A linear stability analysis

2014

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The effect of velocity slip at the walls on the linear stability characteristics of two-fluid three-layer channel flow (the equivalent core-annular configuration in case of pipe) is investigated in the presence of double diffusive (DD) phenomenon. The fluids are miscible and consist of two solute species having different rates of diffusion. The fluids are assumed to be of the same density, but varying viscosity, which depends on the concentration of the solute species. It is found that the flow stabilizes when the less viscous fluid is present in the region adjacent to the slippery channel walls in the single-component (SC) system but becomes unstable at low Reynolds numbers in the presence of DD effect. As the mixed region of the fluids moves towards the channel walls, a new unstable mode (DD mode), distinct from the Tollman Schlichting (TS) mode, arises at Reynolds numbers smaller than the critical Reynolds number for the TS mode. We also found that this mode becomes more prominent when the mixed layer overlaps with the critical layer. It is shown that the slip parameter has nonmonotonic effect on the stability characteristics in this system. Through energy budget analysis, the dual role of slip is explained. The effect of slip is influenced by the location of mixed layer, the log-mobility ratio of the faster diffusing scalar, diffusivity, and the ratio of diffusion coefficients of the two species. Increasing the value of the slip parameter delays the first occurrence of the DD-mode. It is possible to achieve stabilization or destabilization by controlling the various physical parameters in the flow system. In the present study, we suggest an effective and realistic way to control three-layer miscible channel flow with viscosity stratification.

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Section: Introductionmentioning

confidence: 99%

Double-diffusive two-fluid flow in a slippery channel: A linear stability analysis

2014

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“…[15][16][17][18] In miscible core-annular flows, the thickness of the more viscous fluid layer left on the pipe walls and the speed of the propagating "finger" were experimentally investigated by many authors [19][20][21][22][23] and the axisymmetric and "corkscrew" patterns were found. [24][25][26][27][28] In neutrallybuoyant core-annular pipe flows, d'Olce et al 29 observed axisymmetric "pearl" and "mushroom" patterns at high Schmidt number. By an asymptotic analysis, Yang and Yortsos 30 studied miscible displacement Stokes flow between parallel plates and in cylindrical capillary tube with large aspect ratio.…”

Section: Introductionmentioning

confidence: 99%

A study of pressure-driven displacement flow of two immiscible liquids using a multiphase lattice Boltzmann approach

2012

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The pressure-driven displacement of two immiscible fluids in an inclined channel in the presence of viscosity and density gradients is investigated using a multiphase lattice Boltzmann approach. The effects of viscosity ratio, Atwood number, Froude number, capillary number, and channel inclination are investigated through flow structures, front velocities, and fluid displacement rates. Our results indicate that increasing viscosity ratio between the fluids decreases the displacement rate. We observe that increasing the viscosity ratio has a non-monotonic effect on the velocity of the leading front; however, the velocity of the trailing edge decreases with increasing the viscosity ratio. The displacement rate of the thin-layers formed at the later times of the displacement process increases with increasing the angle of inclination because of the increase in the intensity of the interfacial instabilities. Our results also predict the front velocity of the lock-exchange flow of two immiscible fluids in the exchange flow dominated regime. A linear stability analysis has also been conducted in a three-layer system, and the results are consistent with those obtained by our lattice Boltzmann simulations.

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“…Others works have examined the development of 'interfacial' axisymmetric and "corkscrew" patterns that accompany these flows [2,[37][38][39][40]. More recently, axisymmetric "pearl" and "mushroom" patterns were observed experimentally in the case of neutrally-buoyant, miscible core-annular flows in horizontal pipes at high Schmidt number and Reynolds numbers in the range 2-60 [41]. For fixed viscosity ratios, the transition from "pearls" to "mushrooms" occurred with increasing…”

Section: Introductionmentioning

confidence: 99%

Linear stability analysis and numerical simulation of miscible two-layer channel flow

Sahu¹,

Ding²,

Valluri³

et al. 2009

Physics of Fluids

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The stability of miscible two-fluid flow in a horizontal channel is examined. The flow dynamics are governed by the continuity and Navier-Stokes equations coupled to a convective-diffusion equation for the concentration of the more viscous fluid through a concentration-dependent viscosity.Our analysis of the flow in the linear regime delineates the presence of convective and absolute instabilities and identifies the vertical gradients of viscosity perturbations as the main destabilizing influence in agreement with previous work. Our transient numerical simulations demonstrate the development of complex dynamics in the nonlinear regime, characterized by roll-up phenomena and intense convective mixing; these become pronounced with increasing flow rate and viscosity ratio, as well as weak diffusion. *

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Pearl and mushroom instability patterns in two miscible fluids' core annular flows

Cited by 58 publications

References 21 publications

Double-diffusive two-fluid flow in a slippery channel: A linear stability analysis

Double-diffusive two-fluid flow in a slippery channel: A linear stability analysis

A study of pressure-driven displacement flow of two immiscible liquids using a multiphase lattice Boltzmann approach

Linear stability analysis and numerical simulation of miscible two-layer channel flow

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