Direct numerical simulation of gas-particle turbulent swirling flows in an axially rotating pipe (1st Report, Effect of inter particle collisions on particle distributions)

2004 ◽  
Vol 2004.57 (0) ◽  
pp. 307-308
Author(s):  
Hideki USHIJIMA ◽  
Kazuyoshi MATSUZAKI ◽  
Mizue MUNETAKA ◽  
Hideki OHBA
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Swirling Flows ◽  
Particle Collisions ◽  
Particle Distributions

Direct Numerical Simulation of Gas-Particle Turbulent Swirling Flows in an Axially Rotating Pipe

2003 ◽  
Author(s):  
Kazuyoshi Matsuzaki ◽  
Mizue Munekata ◽  
Hideki Ohba
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flows ◽  
Particle Concentration ◽  
Fluid Motion ◽  
Swirling Flows ◽  
Particle Collisions ◽  
Pipe Radius ◽  
The One ◽  
Very High

The purpose of this study is to investigate the effect of the turbulent structure of the swirling flows on the particle motions using numerical simulation. In this work, we deal with the swirling turbulent flows in an axially rotating pipe because of focusing on the influence of swirl effect on the particle motions. Direct numerical simulation (DNS) of gas-particle turbulent swirling flows in the axially rotating pipe at the Reynolds number 180, based on the friction velocity and the pipe radius, and the rotating ratios 0.25 and 0.3 based on the bulk velocity was performed. Particle motions were treated by a Lagragian method with inter-particle collisions calculated by a deterministic method. In order to investigate the influence of swirl effect on the particle motions in detail, the one-way method in which fluid motion is not affected by particles is adopted. In particular, the effect of the inter-particle collisions on particle motions was carefully investigated because it is considered that particles accumulate near the wall due to the centrifugal force and local particle concentration is very high in the region.

scholarly journals Anisotropic Characteristics of Turbulence Dissipation in Swirling Flow: A Direct Numerical Simulation Study

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Xingtuan Yang ◽  
Nan Gui ◽  
Gongnan Xie ◽  
Jie Yan ◽  
Jiyuan Tu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Energy Dissipation ◽  
Direct Numerical Simulation ◽  
Large Scale ◽  
Isotropic Turbulence ◽  
Vortex Breakdown ◽  
Swirling Flow ◽  
Turbulent Energy ◽  
Swirling Flows ◽  
Small Scale

This study investigates the anisotropic characteristics of turbulent energy dissipation rate in a rotating jet flow via direct numerical simulation. The turbulent energy dissipation tensor, including its eigenvalues in the swirling flows with different rotating velocities, is analyzed to investigate the anisotropic characteristics of turbulence and dissipation. In addition, the probability density function of the eigenvalues of turbulence dissipation tensor is presented. The isotropic subrange of PDF always exists in swirling flows relevant to small-scale vortex structure. Thus, with remarkable large-scale vortex breakdown, the isotropic subrange of PDF is reduced in strongly swirling flows, and anisotropic energy dissipation is proven to exist in the core region of the vortex breakdown. More specifically, strong anisotropic turbulence dissipation occurs concentratively in the vortex breakdown region, whereas nearly isotropic turbulence dissipation occurs dispersively in the peripheral region of the strong swirling flows.

Direct numerical simulation of particle collisions in two-phase flows with a meshless method

2008 ◽  
Vol 63 (13) ◽  
pp. 3474-3484 ◽  
Author(s):  
Changfu You ◽  
Xi Wang ◽  
Haiying Qi ◽  
Ruichang Yang ◽  
Delong Xu
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Meshless Method ◽  
Particle Collisions ◽  
Two Phase Flows ◽  
Two Phase

Numerical Study of Vortex Evolution and Correlation between Twin Swirling Flows

2012 ◽  
Vol 516-517 ◽  
pp. 976-979 ◽  
Author(s):  
Nan Gui
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Numerical Study ◽  
Swirling Flows ◽  
Cyclone Separator ◽  
Velocity Correlation ◽  
Swirl Number ◽  
Swirling Jets ◽  
Swirl Flows ◽  
Energy Engineering

Swirling flows are widely used in energy engineering, such as swirling combustor, cyclone separator in pulverized coal burners. The vortex evolution and correlation between twin swirling flows are investigated via direct numerical simulation. Three typical swirl flows with different swirl number are simulated. The structure of vortex evolution, velocity correlation between the twin flows are illustrated and analyzed in detail. The results show the phase-locked correlation of flow velocity between the twin swirling jets which would be useful and helpful for improving the understanding of aerodynamics of multi-swirling systems.

Direct Numerical Simulation of Four Way-Coupled Gas-Solid Flow and Deposition in a Turbulent Channel Flow

2009 ◽  
Author(s):  
Goodarz Ahmadi ◽  
Hojjat Nasr ◽  
John B. McLaughlin
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Channel Flow ◽  
Particle Deposition ◽  
Particle Concentration ◽  
Deposition Velocity ◽  
Time History ◽  
Wall Region ◽  
Particle Collisions ◽  
Coupling Effects

This study was concerned with the effects of particle-particle collisions and two-way coupling on the dispersed and carrier phase turbulence fluctuations in a channel flow. The time history of the instantaneous turbulent velocity vector was generated by the two-way coupled direct numerical simulation (DNS) of the Navier-Stokes equation via a pseudospectral method. The particle equation of motion included the drag and the shear induced lift forces. The effect of particles on the flow was included in the analysis via a feedback force that acted on the computational grid points. Several simulations for different particle relaxation times and particle mass loadings were performed, and the effects of the inter-particle collisions and two-way coupling on the particle deposition velocity, fluid and particle fluctuating velocities, particle normal mean velocity, and particle concentration profiles were determined. It was found that, when particle-particle collisions were included in the computation but two-way coupling effects were ignored, the particle normal fluctuating velocity increased in the wall region causing an increase in the particle deposition velocity. When the particle collisions were neglected but the particle-fluid two-way coupling effects were accounted for, the particle normal fluctuating velocity decreased near the wall causing a decrease in the particle deposition velocity. For the physical case that both inter-particle collisions and two-way coupling effects are present, a series of four-way coupling simulations was performed. It was found that the particle deposition velocity increased with mass loading. The results for the particle concentration profile indicated that the inclusion of either two-way coupling or inter-particle collisions into the computation reduced the accumulation of particles near the wall. Comparisons of the present simulation results with the available experimental data and earlier numerical results were also presented.

A direct numerical simulation study of coherent oscillation effects of swirling flows

Fuel ◽  
2010 ◽  
Vol 89 (12) ◽  
pp. 3926-3933 ◽  
Author(s):  
Nan Gui ◽  
JianRen Fan ◽  
Kefa Cen ◽  
Song Chen
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Simulation Study ◽  
Swirling Flows ◽  
Coherent Oscillation

scholarly journals Direct Numerical Simulation of Particle-Laden Swirling Flows on Turbulence Modulation

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Jie Yan ◽  
Nan Gui ◽  
Gongnan Xie ◽  
Jinsen Gao
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Near Field ◽  
Swirling Flows ◽  
Statistical Characteristics ◽  
Field Region ◽  
Mass Loading ◽  
Small Particles ◽  
Turbulence Modulation ◽  
Number Flow

The modulation of turbulence by the laden particles in swirling flows is studied via direct numerical simulation. The statistical characteristics of turbulence modulation are investigated in detail under the effects of different mass loadings as well as Stokes numbers. It is found that the characteristics of turbulence modulation for different Stokes numbers are very similar to each other when the mass loading is light. As the mass loading increases, small particles seem to modulate turbulence more rapidly than large particles. The number concentration or the number flow rate of particles plays an important role in modulation of turbulence. It induces the preferential attenuation of turbulence for small particles in the near field region. Moreover, the trends of modulation of the axial/azimuthal fluctuations, the turbulent kinetic energy, and the Reynolds stress tenor as well as its invariants are similar in the near field region. However, when the turbulence is decayed sufficiently in the downstream region, the inverse turbulence modulation may occur especially for the regions with local intensive accumulation of small particles.

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