On turbulence modulation by finite-size particles in dilute gas-solid internal flows

2016 ◽  
Vol 301 ◽  
pp. 1259-1263 ◽  
Author(s):  
Kun Luo ◽  
Mingbo Luo ◽  
Jianren Fan
Keyword(s):  
Finite Size ◽  
Internal Flows ◽  
Turbulence Modulation ◽  
Dilute Gas

Phase Doppler anemometry measurements and analysis of turbulence modulation in dilute gas–solid two-phase shear flows

2010 ◽  
Vol 663 ◽  
pp. 434-455 ◽  
Author(s):  
FEI LI ◽  
HAIYING QI ◽  
CHANGFU YOU
Keyword(s):  
Linear Relationship ◽  
Single Phase ◽  
Particle Mass ◽  
Sudden Expansion ◽  
Phase Flow ◽  
Two Phase ◽  
Turbulence Modulation ◽  
Fluctuation Velocity ◽  
Phase Doppler Anemometry ◽  
Dilute Gas

Flow velocities of a dilute gas–solid two-phase flow in a vertical sudden expansion were measured using phase Doppler anemometry to study the behaviour of the turbulence modulation for the stronger shear for various particle mass loadings, inlet Reynolds numbers and particle diameters. The measurements show that the particles changed the gas turbulence by elongation of the entire gas flow field in the downstream direction, which displaced the axial profile of the section-averaged fluctuation velocity in comparison with that of the single-phase flow, and by either the particle inertia reducing the local turbulence or the wake eddy effects enhancing the turbulence. Both mechanisms resulted in an apparent turbulence modulation, which has not been referred to in the related literature, and have led to an ambiguous understanding of turbulence modulation. The elongation and inlet effects should be eliminated to estimate whether the gas turbulence was really modified. The linear relationship between the gas mean velocity gradient and the root-mean-square fluctuation velocity, which was found to be similar to that in single-phase flows, gradually disappeared as the flow developed and the shear intensity reduced. The linear relationship also varied with different conditions. Specifically, the turbulence modulation was enhanced by higher particle mass loadings and the linear relationship disappeared with increasing particle mass loading. This linearity can perhaps be regarded as a criterion for determining the effect of stronger turbulence modulation.

A direct numerical investigation of two-way interactions in a particle-laden turbulent channel flow

2019 ◽  
Vol 875 ◽  
pp. 1096-1144 ◽  
Author(s):  
Cheng Peng ◽  
Orlando M. Ayala ◽  
Lian-Ping Wang
Keyword(s):  
Channel Flow ◽  
Finite Size ◽  
Turbulent Channel Flow ◽  
Spherical Particles ◽  
Homogeneous Distribution ◽  
Particle Sizes ◽  
Small Particles ◽  
Particle Rotation ◽  
Turbulence Modulation ◽  
Budget Analysis

Understanding the two-way interactions between finite-size solid particles and a wall-bounded turbulent flow is crucial in a variety of natural and engineering applications. Previous experimental measurements and particle-resolved direct numerical simulations revealed some interesting phenomena related to particle distribution and turbulence modulation, but their in-depth analyses are largely missing. In this study, turbulent channel flows laden with neutrally buoyant finite-size spherical particles are simulated using the lattice Boltzmann method. Two particle sizes are considered, with diameters equal to 14.45 and 28.9 wall units. To understand the roles played by the particle rotation, two additional simulations with the same particle sizes but no particle rotation are also presented for comparison. Particles of both sizes are found to form clusters. Under the Stokes lubrication corrections, small particles are found to have a stronger preference to form clusters, and their clusters orientate more in the streamwise direction. As a result, small particles reduce the mean flow velocity less than large particles. Particles are also found to result in a more homogeneous distribution of turbulent kinetic energy (TKE) in the wall-normal direction, as well as a more isotropic distribution of TKE among different spatial directions. To understand these turbulence modulation phenomena, we analyse in detail the total and component-wise volume-averaged budget equations of TKE with the simulation data. This budget analysis reveals several mechanisms through which the particles modulate local and global TKE in the particle-laden turbulent channel flow.

Turbulence modulation by finite-size heavy particles in a downward turbulent channel flow

2021 ◽  
Vol 33 (6) ◽  
pp. 063321
Author(s):  
Yan Xia ◽  
Zhaowu Lin ◽  
Dingyi Pan ◽  
Zhaosheng Yu
Keyword(s):  
Channel Flow ◽  
Finite Size ◽  
Turbulent Channel Flow ◽  
Heavy Particles ◽  
Turbulence Modulation

The partial realization theory of finite size two-dimensional arrays

1981 ◽  
Vol 64 (10) ◽  
pp. 1-8
Author(s):  
Tsuyoshi Matsuo ◽  
Yasumichi Hasegawa ◽  
Yoshikuni Okada
Keyword(s):  
Finite Size ◽  
Two Dimensional ◽  
Realization Theory

Turbulence Modulation in a Simplex Spray

1997 ◽  
Vol 24 (1-3) ◽  
pp. 97-107 ◽  
Author(s):  
Wei-Hsiang Lai ◽  
Muh-Rong Wang ◽  
D. Y. Huang
Keyword(s):  
Turbulence Modulation
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