Acceleration of heavy and light particles in turbulence: Comparison between experiments and direct numerical simulations

Volk, Romain; Calzavarini, Enrico; Verhille, Gautier; Lohse, Detlef; Mordant, Nicolas; Pinton, Jean‐François; Toschi, Federico

doi:10.1016/j.physd.2008.01.016

Cited by 82 publications

(98 citation statements)

References 28 publications

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“…However, measurements in high Reynolds flows showed that particles present highly nonGaussian acceleration probability density function (PDF) [5][6][7][8][9][10][11]. The broad probability tails of high acceleration events are related to the highly non-Gaussian PDF of the velocity increments at small scales.…”

Section: Introductionmentioning

confidence: 99%

Modeling the effects of small turbulent scales on the drag force for particles below and above the Kolmogorov scale

Gorokhovski

Zamansky

2018

Phys. Rev. Fluids

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Consistently with observations from recent experiments and DNS, we focus on the effects of strong velocity increments at small spatial scales for the simulation of the drag force on particles in high Reynolds number flows. In this paper, we decompose the instantaneous particle acceleration in its systematic and residual parts. The first part is given by the steady-drag force obtained from the large-scale energy-containing motions, explicitly resolved by the simulation, while the second denotes the random contribution due to small unresolved turbulent scales. This is in contrast with standard drag models in which the turbulent microstructures advected by the large-scale eddies are deemed to be filtered by the particle inertia. In our paper, the residual term is introduced as the particle acceleration conditionally averaged on the instantaneous dissipation rate along the particle path. The latter is modeled from a log-normal stochastic process with locally defined parameters obtained from the resolved field. The residual term is supplemented by an orientation model which is given by a random walk on the unit sphere. We propose specific models for particles with diameter smaller and larger size than the Kolmogorov scale. In the case of the small particles, the model is assessed by comparison with direct numerical simulation (DNS). Results showed that by introducing this modeling, the particle acceleration statistics from DNS is predicted fairly well, in contrast with the standard LES approach. For the particles bigger than the Kolmogorov scale, we propose a fluctuating particle response time, based on an eddy viscosity estimated at the particle scale. This model gives stretched tails of the particle acceleration distribution and dependence of its variance consistent with experiments.

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Section: Introductionmentioning

confidence: 99%

Modeling the effects of small turbulent scales on the drag force for particles below and above the Kolmogorov scale

Gorokhovski

Zamansky

2018

Phys. Rev. Fluids

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“…Advances in the understanding of the statistical characterization of small particle aggregates have been obtained by studying heavy particles advected by stochastic flows [15][16][17][18], and/or in two-dimensional turbulent flows [19]. Temporal properties along single trajectory have been addressed both numerically and experimentally for small, heavy particles and light particles (see, e.g., [20][21][22][23][24][25][26][27][28]), and for large particles, where inertial effects combine with finite size ones (see e.g. [29][30][31]).…”

Section: Introductionmentioning

confidence: 99%

Spatial and velocity statistics of inertial particles in turbulent flows

Bec

Biferale

Cencini

et al. 2011

J. Phys.: Conf. Ser.

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Abstract. Spatial and velocity statistics of heavy point-like particles in incompressible, homogeneous, and isotropic three-dimensional turbulence is studied by means of direct numerical simulations at two values of the Taylor-scale Reynolds number Re λ ∼ 200 and Re λ ∼ 400, corresponding to resolutions of 512 3 and 2048 3 grid points, respectively. Particles Stokes number values range from St ≈ 0.2 to 70. Stationary small-scale particle distribution is shown to display a singular -multifractal-measure, characterized by a set of generalized fractal dimensions with a strong sensitivity on the Stokes number and a possible, small Reynolds number dependency. Velocity increments between two inertial particles depend on the relative weight between smooth events -where particle velocity is approximately the same of the fluid velocity-, and caustic contributions -when two close particles have very different velocities. The latter events lead to a non-differentiable small-scale behaviour for the relative velocity. The relative weight of these two contributions changes at varying the importance of inertia. We show that moments of the velocity difference display a quasi bi-fractal-behavior and that the scaling properties of velocity increments for not too small Stokes number are in good agreement with a recent theoretical prediction made by K. Gustavsson and B. Mehlig arXiv:1012.1789v1 [physics.fludyn], connecting the saturation of velocity scaling exponents with the fractal dimension of particle clustering.

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“…Common examples are represented by small bubbles in liquids, droplets in gases, and aerosols in a generic fluid. The comprehension of the dynamics of these impurities is still an open issue from the theoretical, experimental, and numerical points of view [1][2][3][4][5][6][7][8][9]. Implications are relevant in many applied domains: plankton dynamics in biology [10], chemical reactors, spray combustion and emulsions in industrial engineering [11], planet formation in astrophysics [12], transport of pollutants or floaters, rain initiation and sedimentation processes in geophysics [13].…”

Section: Introductionmentioning

confidence: 99%

Settling velocity of quasi-neutrally-buoyant inertial particles

Afonso

Gama

2017

Comptes Rendus. Mécanique

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We investigate the sedimentation properties of quasi-neutrally buoyant inertial particles carried by incompressible zero-mean fluid flows. We obtain generic formulae for the terminal velocity in generic space-and-time periodic (or steady) flows, along with further information for flows endowed with some degree of spatial symmetry such as odd parity in the vertical direction. These expressions consist in space-time integrals of auxiliary quantities that satisfy partial differential equations of the advection-diffusion-reaction type, which can be solved at least numerically, since our scheme implies a huge reduction of the problem dimensionality from the full phase space to the classical physical space. r é s u m é Nous étudions les propriétés de sédimentation de particules inertielles dotées de flottabilité quasi neutre et transportées par un écoulement incompressible à moyenne nulle. Nous obtenons des formules génériques pour la vitesse terminale dans des écoulements en général périodiques en espace et en temps (ou statiques), avec d'ultérieures informations disponibles pour les écoulements dotés de symétries spatiales spécifiques, telles qu'une parité négative dans la direction verticale. Ces expressions consistent en des intégrales spatio-temporelles de quantités auxiliaires qui obéissent à des équations aux dérivées partielles du type advection-diffusion-réaction. Ces dernières peuvent être résolues au moins numériquement, car notre procédure implique une forte réduction de la dimensionnalité du problème, de l'espace des phases complet à l'espace physique classique.

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Acceleration of heavy and light particles in turbulence: Comparison between experiments and direct numerical simulations

Cited by 82 publications

References 28 publications

Modeling the effects of small turbulent scales on the drag force for particles below and above the Kolmogorov scale

Modeling the effects of small turbulent scales on the drag force for particles below and above the Kolmogorov scale

Spatial and velocity statistics of inertial particles in turbulent flows

Settling velocity of quasi-neutrally-buoyant inertial particles

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