Buoyancy-induced turbulence in a tilted pipe

Hallez, Yannick; Magnaudet, Jacques

doi:10.1017/jfm.2014.638

Cited by 7 publications

(2 citation statements)

References 67 publications

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“…They also have numerous applications in industry, such as in continuous reactors and countercurrent extraction columns (Pratt & Baird 1983;Baird et al 1992). These multiphase flows have been widely studied in the literature, experimentally by Debacq et al (2001), Seon et al (2005Seon et al ( , 2007a, Znaien, Moisy & Hulin (2011) and Alba, Taghavi & Frigaard (2012, 2013a, computationally by Sahu & Vanka (2011), Taghavi, Alba & Frigaard (2012a), Alba, Taghavi & Frigaard (2014), Hallez & Magnaudet (2015) and Sebilleau, Issa & Walker (2016) and analytically by Seon et al (2007b), Taghavi et al (2009, Heavy mixture (H) Light fluid (L) FIGURE 1. (Colour online) Schematic of the symmetric particle-laden exchange flow in a vertical 2D duct used in the lubrication model analysis.…”

Section: Introductionmentioning

confidence: 99%

Monodisperse particle-laden exchange flows in a vertical duct

Mirzaeian

Alba

2018

J. Fluid Mech.

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We study buoyancy-driven exchange flow of two mixtures in a vertical narrow duct (two-dimensional channel as well as pipe) theoretically. While the light mixture is assumed always to be a pure fluid, the heavy mixture can be selected as either a pure or a particle-laden fluid. A small width-to-length ratio considered for the duct ($\unicode[STIX]{x1D6FF}\ll 1$) has been used as the perturbation parameter in developing a lubrication model (negligible inertia). In particular, we have adopted the methodology of Zhou et al. (Phys. Rev. Lett., vol. 94, 2005, 117803) for free-surface particle-laden film flows and extended it to a lock exchange system in confined geometry under the Boussinesq approximation. The resulting model is in the form of the classical Riemann problem and has been solved numerically using a robust total variation diminishing finite difference scheme. Both pure and particle-laden cases are investigated in detail. It is observed that the interface between the two fluids takes a self-similar shape at long times. In the case that both heavy and light fluids are pure, the dynamics of the flow is governed by two dimensionless quantities, namely the Reynolds number, $Re$, and the viscosity ratio, $\unicode[STIX]{x1D705}$, of the light and heavy fluids. The interpenetration of the heavy and light layers increases with $Re$ but decreases with $\unicode[STIX]{x1D705}$. Also, the heights of the heavy and light fronts change with $\unicode[STIX]{x1D705}$ but remain unchanged with $Re$. In the case of the particle-laden flow, however, four additional dimensionless parameters emerge, namely the initial volume fraction of particles, $\unicode[STIX]{x1D719}_{0}$, the ratio of particle diameter to duct width, $r_{p}$, and the density ratios of particles to carrying fluid, $\unicode[STIX]{x1D709}$, and of light fluid to carrying fluid, $\unicode[STIX]{x1D702}$. The effect of these parameters on the dynamics of the flow has been quantified through a systematic approach. In the presence of solid particles, the interface between the heavy and light layers becomes more curved compared to the case of pure fluids. This modification occurs due to the change of heavy mixture viscosity alongside the duct. Novel particle-rich zones are further discovered in the vicinity of the advancing heavy and light fronts. These zones are associated with different transport rates of the fluid and solid particles. The degree of particle enrichment remains the same with $Re$, is enhanced by $\unicode[STIX]{x1D705}$, $r_{p}$ and $\unicode[STIX]{x1D702}$, and is slightly diminished with $\unicode[STIX]{x1D719}_{0}$ and $\unicode[STIX]{x1D709}$. On the other hand, the stretched exchange zone between the heavy and light fronts grows with $r_{p}$, $\unicode[STIX]{x1D702}$ and $Re$, but decays with $\unicode[STIX]{x1D719}_{0}$, $\unicode[STIX]{x1D705}$ and $\unicode[STIX]{x1D709}$.

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Section: Introductionmentioning

confidence: 99%

Monodisperse particle-laden exchange flows in a vertical duct

Mirzaeian

Alba

2018

J. Fluid Mech.

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“…Because the settlement of particles in a vessel is limited by its width, the inclination of the well increases the effective settling area and reduces the distance the particles must travel before they hit the wall, thus greatly increasing the settling rate by orders of magnitude. [7][8][9] .…”

Section: Introductionmentioning

confidence: 99%

Study on the effect of container tilt on the falling speed of suspended particles in gravity field

Pan,

Li,

Guo

et al. 2024

J. Phys.: Conf. Ser.

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The boycott effect is widely used in wastewater purification, drinking water purification, and mixture treatment in industry and manufacturing. In this paper, we analyze the settling velocity of particles in the clear water and suspended zones, and investigate the reasons for the tilting angle of the vessel to accelerate the settling velocity of particles. This paper uses video tracking software to analyze the settling velocity of particles in the experiment and draws conclusions.

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Non-isothermal buoyancy-driven exchange flows in inclined pipes

et al. 2017

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We study non-isothermal buoyancy-driven exchange flow of two miscible Newtonian fluids in an inclined pipe experimentally. The heavy cold fluid is released into the light hot one in an adiabatic small-aspect-ratio pipe under the Boussinesq limit (small Atwood number). At a fixed temperature, the two fluids involved have the same viscosity. Excellent qualitative and quantitative agreement is first found against rather recent studies in literature on isothermal flows where the driving force of the flow comes from salinity as opposed to temperature difference. The degree of flow instability and mixing enhances as the pipe is progressively inclined towards vertical. Similar to the isothermal limit, maximal rate of the fluids interpenetration in the non-isothermal case occurs at an intermediate angle, β. The interpenetration rate increases with the temperature difference. The degree of fluids mixing and diffusivity is found to increase in the non-isothermal case compared to the isothermal one. There has also been observed a novel asymmetric behavior in the flow, never reported before in the isothermal limit. The cold finger appears to advance faster than the hot one. Backed by meticulously designed supplementary experiments, this asymmetric behavior is hypothetically associated with the wall contact and the formation of a warm less-viscous film of the fluid lubricating the cold more-viscous finger along the pipe. On the other side of the pipe, a cool more-viscous film forms decelerating the hot less-viscous finger. Double diffusive effects associated with the diffusion of heat and mass (salinity) are further investigated. In this case and for the same range of inclination angles and density differences, the level of flow asymmetry is found to decrease. The asymmetric behaviour of the flow is quantified over the full range of experiments. Similar to the study of Salort et al. [“Turbulent velocity profiles in a tilted heat pipe,” Phys. Fluids 25(10), 105110-1–105110-16 (2013)] for tilted heat pipes, a small Richardson number of Ri≈0.05 is found, above which flow laminarization occurs. In terms of the dimensionless numbers of the problem, it is found that the interpenetrative speeds of the heavy and light fluid layers in non-isothermal and double-diffusive cases increase with the dimensionless temperature difference, rT, Atwood number, At, Grashof number, Gr, Reynolds number, Re, Nahme number, Na, and Péclet number, Pe but decreases with Prandtl number, Pr, and Brinkman number, Br.

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Buoyancy-induced turbulence in a tilted pipe

Cited by 7 publications

References 67 publications

Monodisperse particle-laden exchange flows in a vertical duct

Monodisperse particle-laden exchange flows in a vertical duct

Study on the effect of container tilt on the falling speed of suspended particles in gravity field

Non-isothermal buoyancy-driven exchange flows in inclined pipes

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