Numerical Study for Estimating Drag and Lift Forces Acting on a Spherical Bubble in a Homogeneous Shear Flow.

In this work, we studied the deformation behavior of a droplet under the various flow conditions. The droplet deformation is calculated by a level-set method. In order to determine the acting force on a particle in shear flow field, we propose the feedback forces which can maintain particle position with efficient handling of deformation. Computations were carried out to investigate the deformation behavior of a droplet caused by the surrounding gaseous flow and the effect of the deformation on the droplet characteristics with various dimensionless parameters. Based on the numerical results, we observed that drag and lift forces acting on a droplet depend strongly on the deformation. Also, the present method is proven to be applicable to a three-dimensional deformation of droplet in shear flow, which cannot be properly analyzed by the previous studies. The drag and lift forces obtained from the present numerical method are favorably compared with the data reported in the literature.

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Drag and Lift Forces Acting on a Sphere in Shear Flow of Power-Law Fluid

Journal of Engineering Thermophysics ◽

10.1134/s1810232818040094 ◽

2018 ◽

Vol 27 (4) ◽

pp. 474-488 ◽

Cited By ~ 1

Author(s):

A. A. Gavrilov ◽

K. A. Finnikov ◽

Ya. S. Ignatenko ◽

O. B. Bocharov ◽

R. May

Keyword(s):

Shear Flow ◽

Power Law ◽

Power Law Fluid ◽

Lift Forces ◽

Drag And Lift

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Vertically localised equilibrium solutions in large-eddy simulations of homogeneous shear flow

Journal of Fluid Mechanics ◽

10.1017/jfm.2017.450 ◽

2017 ◽

Vol 827 ◽

pp. 225-249 ◽

Cited By ~ 7

Author(s):

Atsushi Sekimoto ◽

Javier Jiménez

Keyword(s):

Shear Flow ◽

Vertical Direction ◽

Large Eddy Simulations ◽

Small Scale ◽

Box Dimension ◽

Equilibrium Solutions ◽

Vortical Structures ◽

Homogeneous Shear ◽

Large Eddy ◽

Homogeneous Shear Flow

Unstable equilibrium solutions in a homogeneous shear flow with sinuous (streamwise-shift-reflection and spanwise-shift-rotation) symmetry are numerically found in large-eddy simulations (LES) with no kinetic viscosity. The small-scale properties are determined by the mixing length scale $l_{S}$ used to define eddy viscosity, and the large-scale motion is induced by the mean shear at the integral scale, which is limited by the spanwise box dimension $L_{z}$. The fraction $R_{S}=L_{z}/l_{S}$, which plays the role of a Reynolds number, is used as a numerical continuation parameter. It is shown that equilibrium solutions appear by a saddle-node bifurcation as $R_{S}$ increases, and that the flow structures resemble those in plane Couette flow with the same sinuous symmetry. The vortical structures of both lower- and upper-branch solutions become spontaneously localised in the vertical direction. The lower-branch solution is an edge state at low $R_{S}$, and takes the form of a thin critical layer as $R_{S}$ increases, as in the asymptotic theory of generic shear flow at high Reynolds numbers. On the other hand, the upper-branch solutions are characterised by a tall velocity streak with multiscale multiple vortical structures. At the higher end of $R_{S}$, an incipient multiscale structure is found. The LES turbulence occasionally visits vertically localised states whose vortical structure resembles the present vertically localised LES equilibria.

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Anisotropic clustering of inertial particles in homogeneous shear flow

Journal of Fluid Mechanics ◽

10.1017/s002211200900648x ◽

2009 ◽

Vol 629 ◽

pp. 25-39 ◽

Cited By ~ 63

Author(s):

P. GUALTIERI ◽

F. PICANO ◽

C. M. CASCIOLA

Keyword(s):

Relaxation Time ◽

Shear Flow ◽

Large Scale ◽

Inertial Particles ◽

Spatial Homogeneity ◽

Homogeneous Shear ◽

Multi Scale ◽

Angular Distribution Function ◽

Homogeneous Shear Flow ◽

Anisotropic Clustering

Recently, clustering of inertial particles in turbulence has been thoroughly analysed for statistically homogeneous isotropic flows. Phenomenologically, spatial homogeneity of particle configurations is broken by the advection of a range of eddies determined by the Stokes relaxation time of the particles. This in turn results in a multi-scale distribution of local particle concentration and voids. Much less is known concerning anisotropic flows. Here, by addressing direct numerical simulations (DNS) of a statistically steady particle-laden homogeneous shear flow, we provide evidence that the mean shear preferentially orients particle patterns. By imprinting anisotropy on large-scale velocity fluctuations, the shear indirectly affects the geometry of the clusters. Quantitative evaluation is provided by a purposely designed tool, the angular distribution function (ADF) of particle pairs, which allows to address the anisotropy content of particle aggregates on a scale-by-scale basis. The data provide evidence that, depending on the Stokes relaxation time of the particles, anisotropic clustering may occur even in the range of scales in which the carrier phase velocity field is already recovering isotropy. The strength of the singularity in the anisotropic component of the ADF quantifies the level of fine-scale anisotropy, which may even reach values of more than 30% direction-dependent variation in the probability to find two closeby particles at viscous-scale separation.

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