Modulation of homogeneous turbulence seeded with finite size bubbles or particles

Yeo, Kyongmin; Dong, Shen; Climent, Éric; Maxey, Martin

doi:10.1016/j.ijmultiphaseflow.2009.11.001

Cited by 67 publications

(65 citation statements)

References 66 publications

(96 reference statements)

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“…Heavy solid particles also show organized distributions of number concentrations in flows. 48,49 Bosse and Kleiser 48 presented the heavy particle motion simulated by a point-force coupling model with an Eulerian-Lagrangian LES in an isotropic homogeneous turbulence: The particle concentration distribution is formed by the vortical structure, and thus highly concentrated heavy particles preferentially settle down in the downward flow region of the continuous phase. Further, in settling, the preferentially dispersed particles selectively modify the flow structure, as represented in the power spectra of the spatial velocity fluctuation.…”

Section: Discussionmentioning

confidence: 99%

Intensified and attenuated waves in a microbubble Taylor–Couette flow

2013

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The effect of the presence of microbubbles on a flow state is experimentally investigated in a Taylor-Couette flow with azimuthal waves, in order to examine the interaction mechanism of bubbles and flows that result in drag reduction. The average diameter of the bubbles is 60 μm, which is smaller than the Kolmogorov length scale, and the maximum void fraction is 1.2 × 10 −4 at the maximum case. The modifications of the fluid properties, bulk density, effective viscosity, and the extra energy input caused by the addition of microbubbles are expected to have a small effect on modifying flow states. The power of the basic wave propagating in the azimuthal direction is enhanced; its modulation, however, is decreased by adding microbubbles in the flow regime corresponding to modulated Taylor vortex flow. Moreover, the gradient of the azimuthal velocity near the walls, source of the wall shear stress, decreases by 10%. The modified velocity distribution by adding microbubbles is comparable to that obtained with a 20% lower Reynolds number. Microbubbles in the coherent structure of the wavy Taylor vortices are visualized and exhibit a preferential distribution and motion at the crests and troughs of the waviness. The roles of the inhomogeneously distributed microbubbles in wavy vortical structures are discussed in view of our findings. C 2013 AIP Publishing LLC. [http://dx

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Section: Discussionmentioning

confidence: 99%

Intensified and attenuated waves in a microbubble Taylor–Couette flow

2013

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“…[12,13] The floating micromotors affect the fluidic process and its capillary dynamics, by a complex interplay of factors including: the size and rate of bubble formation, the size and number of the oxygen evolving seeds on the particle surface, the finite size of the particles suspended in the liquid and its viscosity. [15] We expect that the bimolecular catalytic event is herein the major driving force to sustain the bubble-induced velocity fluctuation and turbulent flow. Indeed, fitting of the experimental curves of Figure 4 b, shows that, while in the absence of H 2 O 2 the flow dynamics of the starting regime (S zone, time interval of about 100 s) corresponds to a pure capillarity behavior, increasing the H 2 O 2 concentration imparts a remarkable flow acceleration, which turns out to be dependent on H 2 O 2 concentration.…”

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confidence: 99%

Catalytic Self‐Propulsion of Supramolecular Capsules Powered by Polyoxometalate Cargos

Mercato

Carraro

Zizzari

et al. 2014

Chemistry A European J

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Multicompartment, spherical microcontainers were engineered through a layer-by-layer polyelectrolyte deposition around a fluorescent core while integrating a ruthenium polyoxometalate (Ru4POM), as molecular motor, vis-à-vis its oxygenic, propeller effect, fuelled upon H2O2 decomposition. The resulting chemomechanical system, with average speeds of up to 25 μm s(-1), is amenable for integration into a microfluidic set-up for mixing and displacement of liquids, whereby the propulsion force and the resulting velocity regime can be modulated upon H2O2-controlled addition.

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“…In addition, Lucci et al (2010) numerically simulated the turbulent flow around moving spherical particles dispersed in a decaying isotropic turbulent flow. Yeo et al (2010) investigated the modulation of isotropic turbulent flows induced by spherical bubbles, neutrally buoyant particles and slightly inertial particles. They also used the repulsive force between the particle surfaces when the gap is less than a critical value.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic force and torque models for a particle moving near a wall at finite particle Reynolds numbers

Zhou

Jin

Tian

et al. 2017

International Journal of Multiphase Flow

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: Models for hydrodynamic force and torque Finite particle Reynolds number Near-wall effect Particle-resolved simulation Sub-grid scale model Eulerian-Lagrangian simulation a b s t r a c t This research work is aimed at proposing models for the hydrodynamic force and torque experienced by a spherical particle moving near a solid wall in a viscous fluid at finite particle Reynolds numbers. Conventional lubrication theory was developed based on the theory of Stokes flow around the particle at vanishing particle Reynolds number. In order to account for the effects of finite particle Reynolds number on the models for hydrodynamic force and torque near a wall, we use four types of simple motions at different particle Reynolds numbers. Using the lattice Boltzmann method and considering the moving boundary conditions, we fully resolve the flow field near the particle and obtain the models for hydrodynamic force and torque as functions of particle Reynolds number and the dimensionless gap between the particle and the wall. The resolution is up to 50 grids per particle diameter. After comparing numerical results of the coefficients with conventional results based on Stokes flow, we propose new models for hydrodynamic force and torque at different particle Reynolds numbers. It is shown that the particle Reynolds number has a significant impact on the models for hydrodynamic force and torque. Furthermore, the models are validated against general motions of a particle and available modeling results from literature. The proposed models could be used as sub-grid scale models where the flows between particle and wall can not be fully resolved, or be used in Lagrangian simulations of particle-laden flows when particles are close to a wall instead of the currently used models for an isolated particle.

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Modulation of homogeneous turbulence seeded with finite size bubbles or particles

Cited by 67 publications

References 66 publications

Intensified and attenuated waves in a microbubble Taylor–Couette flow

Intensified and attenuated waves in a microbubble Taylor–Couette flow

Catalytic Self‐Propulsion of Supramolecular Capsules Powered by Polyoxometalate Cargos

Hydrodynamic force and torque models for a particle moving near a wall at finite particle Reynolds numbers

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