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Journal ArticleDOI

Turbulent Dispersed Multiphase Flow

01 Jan 2010-Annual Review of Fluid Mechanics (Annual Reviews)-Vol. 42, Iss: 42, pp 111-133
TL;DR: A review of the current state-of-the-art experimental and computational techniques for turbulent dispersed multiphase flows, their strengths and limitations, and opportunities for the future can be found in this paper.
Abstract: Turbulent dispersed multiphase flows are common in many engineering and environmental applications. The stochastic nature of both the carrier-phase turbulence and the dispersed-phase distribution makes the problem of turbulent dispersed multiphase flow far more complex than its single-phase counterpart. In this article we first review the current state-of-the-art experimental and computational techniques for turbulent dispersed multiphase flows, their strengths and limitations, and opportunities for the future. The review then focuses on three important aspects of turbulent dispersed multiphase flows: the preferential concentration of particles, droplets, and bubbles; the effect of turbulence on the coupling between the dispersed and carrier phases; and modulation of carrier-phase turbulence due to the presence of particles and bubbles.
Citations
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Journal ArticleDOI
TL;DR: A strategy capable of simulating polydisperse flows in complex geometries is employed where the fluid transport equations are solved in an Eulerian framework and the dispersed phase is represented as Lagrangian particles.

414 citations


Cites background from "Turbulent Dispersed Multiphase Flow..."

  • ...Another noteworthy review on that topic is due to Balanchandar and Eaton [2], where the current state-of-the-art experimental and computational techniques for turbulent dilute dispersed flows are discussed....

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Journal ArticleDOI
TL;DR: In this paper, the authors provide a review of computational model developments relevant for turbulent dilute spray combustion, and some of the most important experiments in this field are presented in a structured way with the intention of providing a database for model validation and a guideline for future investigations.

285 citations

Journal ArticleDOI
TL;DR: The preferential concentration of inertial particles in turbulent flows has been extensively investigated since the 1960s as discussed by the authors, and the main mathematical analysis techniques which have been developed and implemented up to now to diagnose and characterize the clustering properties of dispersed particles.

260 citations


Cites background from "Turbulent Dispersed Multiphase Flow..."

  • ...…as USt = n0St (with St the usual Stokes number and n0 the average number of particles in a dissipative eddy) which they have shown to give a better collapse of experimental data on turbulence modulation (see also the reviews by Poelma and Ooms, 2006; Balachandar and Eaton, 2010 on this question)....

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  • ...Investigations mostly focused on the modulation of the turbulence by particles, on particle dispersion, on the clustering and on its consequences on the settling velocity as well as – but to a lesser extent – on the dispersion (see Balachandar and Eaton, 2010 for a recent review)....

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Journal ArticleDOI
TL;DR: Anisotropic particles are common in many industrial and natural turbulent flows as discussed by the authors, and when these particles are small and neutrally buoyant, they follow Lagrangian trajectories while exhibiting rich orientational dynamics from the coupling of their rotation to the velocity gradients of the turbulence field.
Abstract: Anisotropic particles are common in many industrial and natural turbulent flows. When these particles are small and neutrally buoyant, they follow Lagrangian trajectories while exhibiting rich orientational dynamics from the coupling of their rotation to the velocity gradients of the turbulence field. This system has proven to be a fascinating application of the fundamental properties of velocity gradients in turbulence. When particles are not neutrally buoyant, they experience preferential concentration and very different preferential alignment than neutrally buoyant tracer particles. A vast proportion of the parameter range of anisotropic particles in turbulence is still unexplored, with most existing research focusing on the simple foundational cases of axisymmetric ellipsoids at low concentrations in homogeneous isotropic turbulence and in turbulent channel flow. Numerical simulations and experiments have recently developed a fairly comprehensive picture of alignment and rotation in these cases, and t...

257 citations


Cites background or methods from "Turbulent Dispersed Multiphase Flow..."

  • ...…DNS is able to solve for all scales of motion, down to the smallest, it has been particularly valuable to the study of turbulent dispersed flows, in which the limiting case of small spherical particles has received extensive attention (Elghobashi & Prosperetti 2009, Balachandar & Eaton 2010)....

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  • ...In Eulerian-Lagrangian simulations, momentum coupling between spherical particles and fluid is mostly done via the point-force approximation (e.g., Crowe et al. 1996, Balachandar & Eaton 2010), which usually neglects the torque coupling (Andersson et al. 2012)....

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  • ...Beyond the complexity of turbulence and of multiphase flows with spherical particles (Balachandar & Eaton 2010), we now have to consider forces and torques that depend on particle orientation....

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Journal ArticleDOI
TL;DR: A review of particle-resolved direct numerical simulation (PR-DNS) of the microscale governing equations for understanding gas-solid flow physics and obtaining quantitative information for model development is presented in this article.
Abstract: Gas-solid flows in nature and industrial applications are characterized by multiscale and nonlinear interactions that manifest as rich flow physics and pose unique modeling challenges. In this article, we review particle-resolved direct numerical simulation (PR-DNS) of the microscale governing equations for understanding gas-solid flow physics and obtaining quantitative information for model development. A clear connection between a microscale realization and meso/macroscale representation is necessary for PR-DNS to be used effectively for model development at the meso- and macroscale. Furthermore, the design of PR-DNS must address the computational challenges of parameterizing models in a high-dimensional parameter space and obtaining accurate statistics of flow properties from a finite number of realizations at acceptable grid resolution. This review also summarizes selected recent insights into the physics of momentum, kinetic energy, and heat transfer in gas-solid flows obtained from PR-DNS. Promising future applications of PR-DNS include the study of the effect of number fluctuations on hydrodynamics, instabilities in gas-solid flow, and wall-bounded flows.

255 citations

References
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BookDOI
26 Aug 2011
TL;DR: In this article, the authors present a test case for a single-phase flow Turbulence Modulation by Particles (SPM) model using the Brownian Motion model.
Abstract: Introduction Industrial Applications Energy Conversion and Propulsion Fire Suppression and Control Summary Properties of Dispersed Phase Flows Concept of a Continuum Density and Volume Fraction Particle or Droplet Spacing Response Times Stokes Number Dilute versus Dense Flows Phase Coupling Properties of an Equilibrium Mixture Summary Exercises Size Distribution Discrete Size Distributions Continuous Size Distributions Statistical Parameters Frequently Used Size Distributions Summary Exercises Particle-Fluid Interaction Single-Particle Equations Mass Coupling Linearmomentumcoupling Energy Coupling Summary Exercises Particle-Particle Interaction Particle-Particle Interaction Particle-Wall Interaction Summary Exercises Continuous Phase Equations Averaging Procedures Volume Averaging Property Flux Through a Particle Cloud Volume-Averaged Conservation Equations Equation Summary Summary Exercises Turbulence Review of Turbulence in Single-Phase Flow Turbulence Modulation by Particles Review of Modulation Models Basic Test Case for Turbulence Models Volume-Averaged Turbulence Models Application to Experimental Results Summary Exercises Droplet-Particle Cloud Equations Discrete Element Method (DEM) Discrete Parcel Method (DPM) Two-Fluid Model PDF Models Summary Numerical Modeling Complete Numerical Simulation DNS Models LES Models VANS Numerical Models Summary Experimental Methods Sampling Integral Methods Local Measurement Techniques Summary Exercises Appendix A: Single-Particle Equations Appendix B: Volume Averaging Appendix C: Volume-Averaged Equations Appendix D: Turbulence Equations 425 Appendix E: Brownian Motion References Nomenclature Index

2,821 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a joint probability density function (pdf) of the three components of velocity and of the composition variables (species mass fractions and enthalpy) to calculate the properties of turbulent reactive flow fields.

2,578 citations

Journal ArticleDOI
TL;DR: An overview of the challenges and progress associated with the task of numerically predicting particle-laden turbulent flows is provided and suggestions are made for improving closure modelling of some important correlations.
Abstract: The paper provides an overview of the challenges and progress associated with the task of numerically predicting particle-laden turbulent flows The review covers the mathematical methods based on turbulence closure models as well as direct numerical simulation (DNS) In addition, the statistical (pdf) approach in deriving the dispersed-phase transport equations is discussed The review is restricted to incompressible, isothermal flows without phase change or particle-particle collision Suggestions are made for improving closure modelling of some important correlations

1,328 citations

Journal ArticleDOI
Martin R. Maxey1
TL;DR: In this article, the average settling velocity in homogeneous turbulence of a small rigid spherical particle subject to a Stokes drag force was shown to depend on the particle inertia and the free-fall terminal velocity in still fluid.
Abstract: The average settling velocity in homogeneous turbulence of a small rigid spherical particle, subject to a Stokes drag force, is shown to depend on the particle inertia and the free-fall terminal velocity in still fluid. With no inertia the particle settles on average at the same rate as in still fluid, assuming there is no mean flow. Particle inertia produces a bias in each trajectory towards regions of high strain rate or low vorticity, which affects the mean settling velocity. Results from a Gaussian random velocity field show that this produces an increased settling velocity.

1,023 citations

Journal ArticleDOI
TL;DR: Preferential concentration describes the accumulation of dense particles within specific regions of the instantaneous turbulence field as mentioned in this paper, which occurs in dilute particle-laden flows with particle time constants of the same order as an appropriately chosen turbulence time scale.

969 citations