Simultaneous measurements of deforming Hinze-scale bubbles with surrounding turbulence

Masuk, Ashik Ullah Mohammad; Salibindla, Ashwanth; Ni, Rui

doi:10.1017/jfm.2020.933

Cited by 38 publications

(22 citation statements)

References 48 publications

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“…where σ is the surface tension coefficient, ρ c is the carrier phase density and ε is the energy dissipation rate. This estimate proved valid for bubbles (Chan et al 2021;Masuk, Salibindla & Ni 2021) and emulsions (Perlekar et al 2012;Mukherjee et al 2019;Rosti et al 2020;Yi et al 2021). Different O(1) values have been reported for We c in numerical (Rivière et al 2021) and experimental works (Deane & Stokes 2002;Lemenand et al 2017), from 0.5 up to 5; for dilute emulsions in turbulence We c ≈ 1.17, according to the values from both numerical (Perlekar et al 2012) and experimental (Yi et al 2021) data.…”

Section: Observations On Droplet Size Distributionmentioning

confidence: 71%

Modulation of homogeneous and isotropic turbulence in emulsions

et al. 2022

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We present a numerical study of emulsions in homogeneous and isotropic turbulence (HIT) at $Re_\lambda =137$ . The problem is addressed via direct numerical simulations, where the volume of fluid is used to represent the complex features of the liquid–liquid interface. We consider a mixture of two iso-density fluids, where fluid properties are varied with the goal of understanding their role in turbulence modulation, in particular the volume fraction ( $0.03<\alpha <0.5$ ), viscosity ratio ( $0.01<\mu _d/\mu _c<100$ ) and large-scale Weber number ( $10.6< We_\mathcal {L}<106.5$ ). The analysis, performed by studying integral quantities and spectral scale-by-scale analysis, reveals that energy is transported consistently from large to small scales by the interface, and no inverse cascade is observed. Furthermore, the total surface is found to be directly proportional to the amount of energy transported, while viscosity and surface tension alter the dynamic that regulates energy transport. We also observe the $-10/3$ and $-3/2$ scaling on droplet size distributions, suggesting that the dimensional arguments that led to their derivation are verified in HIT conditions.

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Section: Observations On Droplet Size Distributionmentioning

confidence: 71%

Modulation of homogeneous and isotropic turbulence in emulsions

et al. 2022

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“…where q is the density of the carrier phase, r the surface tension, and e the fluid turbulent dissipation rate. A reference value for the dissipation is commonly assumed when computing the Hinze diameter; however, due to turbulence intermittency and to variations in the local dissipation (i.e., presence of turbulent eddies with different sizes and energy contents), the Hinze diameter does not mark a sharp threshold [258] and is instead a reference scale separating two regimes, the coalescence-dominated regime, for drops smaller than the Hinze scale, and the breakage-dominated regime, for drops larger than the Hinze scale. The physical mechanisms generating the DSD are complex and hard to disentangle; however, broadly speaking the DSD can be considered as the ultimate result of drop-drop and drop-turbulence interactions, namely, coalescence and breakage events.…”

Section: Drop Size Distribution and Advancementsmentioning

confidence: 99%

Turbulent Flows With Drops and Bubbles: What Numerical Simulations Can Tell Us—Freeman Scholar Lecture

Soligo

Roccon

Soldati

2021

Journal of Fluids Engineering

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Turbulent flows laden with large, deformable drops or bubbles are ubiquitous in nature and in a number of industrial processes. These flows are characterized by a physics acting at many different scales: from the macroscopic length scale of the problem down to the microscopic molecular scale of the interface. Naturally, the numerical resolution of all the scales of the problem, which span about eight to nine orders of magnitude, is not possible, with the consequence that numerical simulations of turbulent multiphase flows impose challenges and require methods able to capture the multi-scale nature of the flow. In this review, we start by describing the numerical methods commonly employed and discussing their advantages and limitations, and then we focus on the issues arising from the limited range of scales that can be possibly solved. Ultimately, the droplet size distribution, a key result of interest for turbulent multiphase flows, is used as a benchmark to compare the capabilities of the different methods and to discuss the main insights that can be drawn from these simulations. Based on this, we define a series of guidelines and best practices that we believe important in the simulation analysis and in the development of new numerical methods.

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“…2011; Riboux, Legendre & Risso 2013; Bouche et al. 2014; Lai & Socolofsky 2019); (iii) bubbles wakes introduce additional turbulence and enhance turbulence dissipation rates in the vicinity of the bubble surface (Santarelli, Roussel & Fröhlich 2016; du Cluzeau, Bois & Toutant 2019; Masuk, Salibindla & Ni 2021 b ); (iv) modulation of the liquid mean velocity profile due to interphase momentum transfer, resulting in modifications to the background shear-induced turbulence (Lu & Tryggvason 2008; Bragg et al. 2021).…”

Section: Introductionmentioning

confidence: 99%

An experimental study on the multiscale properties of turbulence in bubble-laden flows

Hessenkemper

Lucas

et al. 2022

J. Fluid Mech.

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The properties of bubble-laden turbulent flows at different scales are investigated experimentally, focusing on the flow kinetic energy, energy transfer and extreme events. The experiments employed particle shadow velocimetry measurements to measure the flow in a column generated by a homogeneous bubble swarm rising in water, for two different bubble diameters ( $2.7$ mm and $3.9$ mm) and moderate gas volume fractions ( $0.26\,\%\sim 1.31\,\%$ ). The two velocity components were measured at high resolution, and used to construct structure functions up to twelfth order for separations spanning the small to large scales in the flow. Concerning the flow anisotropy, the velocity structure functions are found to differ for separations in the vertical and horizontal directions of the flow, and the cases with smaller bubbles are the most anisotropic, with a dependence on void fraction. The degree of anisotropy is shown to increase as the order of the structure functions is increased, showing that extreme events in the flow are the most anisotropic. Our results show that the average energy transfer with the horizontal velocity component is downscale, just as for the three-dimensional single-phase turbulence. However, the energy transfer associated with the vertical component of the fluid velocity is upscale. The probability density functions of the velocity increments reveal that extreme values become more probable with decreasing Reynolds number, the opposite of the behaviour in single-phase turbulence. We visualize those extreme events and find that regions of intense small-scale velocity increments occur near the turbulent/non-turbulent interface at the boundary of the bubble wake.

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Simultaneous measurements of deforming Hinze-scale bubbles with surrounding turbulence

Abstract: Abstract

Cited by 38 publications

References 48 publications

Modulation of homogeneous and isotropic turbulence in emulsions

Modulation of homogeneous and isotropic turbulence in emulsions

Turbulent Flows With Drops and Bubbles: What Numerical Simulations Can Tell Us—Freeman Scholar Lecture

An experimental study on the multiscale properties of turbulence in bubble-laden flows

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