Mixing, Chaotic Advection, and Turbulence

Ottino, Julio M.

doi:10.1146/annurev.fl.22.010190.001231

Cited by 542 publications

(316 citation statements)

References 101 publications

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“…This suggests exponential interface stretching and thus is a strong indication of chaotic advection. 5 Hence, the measured scalar fields provide experimental evidence in support of the earlier claim based on the Poincaré FIG. 18.…”

Section: B 3d Lagrangian Transportsupporting

confidence: 83%

“…In the past few decades, the fundamentals and applications of mass/scalar transport in spatially periodic laminar flows have been studied in numerous theoretical and numerical investigations. [5][6][7][8][9][10][11][12] Nevertheless, a complete understanding is not achieved yet. Particularly, experimental studies are limited, i.e., restricted to highly idealized flow geometries or allowing only partial access to the flow domain with (optical) diagnostic tools.…”

Section: Introductionmentioning

confidence: 99%

“…Particularly, experimental studies are limited, i.e., restricted to highly idealized flow geometries or allowing only partial access to the flow domain with (optical) diagnostic tools. 5,[13][14][15][16] The work presented here aims to bridge this gap via laboratory experiments in a real mixer geometry.…”

Section: Introductionmentioning

confidence: 99%

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Scalar transport in inline mixers with spatially periodic flows

et al. 2017

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Spatially persisting patterns form during the downstream evolution of passive scalars in three-dimensional (3D) spatially periodic flows due to the coupled effect of stretching and folding mechanisms of the flow field. This has been investigated in many computational and theoretical studies of 2D time-periodic and 3D spatially periodic flow fields. However, experimental studies, to date, have mainly focused on flow visualization with streaks of dye rather than fully 3D scalar field measurements. Our study employs 3D particle tracking velocimetry and 3D laser-induced fluorescence to analyze the evolution of 3D flow and scalar fields and the correlation between the coherent flow/scalar field structures in a representative inline mixer, the Quatro static mixer. For this purpose an experimental setup that consists of an optically accessible test section with transparent internal elements accommodating a pressure-driven pipe flow has been built. The flow and scalar fields clearly underline the complementarity of the experimental results with numerical simulations and provide validation of the periodicity assumption needed in numerical studies. The experimental procedure employed in this investigation, which allows studying the scalar transport in the advective limit, demonstrates the suitability of the present method for exploratory mixing studies of a variety of mixing devices, beyond the Quatro static mixer.

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Section: B 3d Lagrangian Transportsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

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Scalar transport in inline mixers with spatially periodic flows

et al. 2017

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“…Efficient mixing has been shown to occur with protocols producing chaotic pathlines and so-called chaotic advection. [11][12][13][14] Stretching and folding of fluid elements were shown to play a crucial role, increasing the interface area between the two fluids and the concentration gradients, thereby intensifying the mixing process. [15][16][17][18][19][20] In the field of dense granular flows where grains tend to transiently rotate in rotational islands, the advection-diffusion coupling leads to a significant transfer enhancement.…”

Section: Introductionmentioning

confidence: 99%

How rotational vortices enhance transfers

et al. 2013

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Inspired by recent observations of granular flow, we examine how rotational vortices contribute to heat or mass transfer enhancement in a fluid. We use a tracer method to simulate both diffusion and advection in systems of differing intrinsic diffusivities D 0 , vortex sizes R, vortex rotation frequencies f, and vortex lifetimes . The results reveal that these systems exhibit an effective diffusive behavior, characterized by an effective diffusivity

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“…The knowledge base, however, is less developed than that for fluids (Ottino 1990;Ottino and Khakhar, 2000). Achieving a mixture perfectly homogeneous in terms of composition of the gas or the liquid in the case of dissolving components is not that difficult, while in the case of granular components, with particles varying in size and density, obtaining a homogeneous and random mixture is practically impossible (Borowski et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Analysis of kinetics of multicomponent, heterogeneous granular mixtures - Laminar and turbulent flow approach

Królczyk

2016

Chemical and Process Engineering

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Mixing of granular materials is unquestionably important. Mixing solids is common in industrial applications and frequently represents a critical stage of the processes. The effect of mixing determines the quality of the products. Achieving a gas or liquid mixture ideally homogeneous in terms of composition in the case of dissolving components is not that difficult, while in case of granular materials that usually differ in sizes and densities, obtaining a homogenous mixture is practically impossible. The aim of the paper is to present the kinetics of mixing of a multicomponent, nonhomogeneous granular mixture. For the first time in mixing of granular materials, a reference has been made to the terminology used in kinematics of fluid mixtures to determine the state of the mixture: turbulent or laminar. By means of statistical analysis the mixing process was divided into two stages. The initial phase of the process was called the stage of turbulent changes, due to large differences in the quality of the observed mixtures; the final step of the process was called the stage of laminar, stable changes, where further mixing did not result in a significant improvement in quality. The research was conducted in industrial conditions in a twotonne mixer.

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Mixing, Chaotic Advection, and Turbulence

Cited by 542 publications

References 101 publications

Scalar transport in inline mixers with spatially periodic flows

Scalar transport in inline mixers with spatially periodic flows

How rotational vortices enhance transfers

Analysis of kinetics of multicomponent, heterogeneous granular mixtures - Laminar and turbulent flow approach

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