Two-fluid turbulence modeling of swirling gas-particle flows — A review

2017 ◽  
Vol 314 ◽  
pp. 253-263 ◽  
Author(s):  
Lixing Zhou
Keyword(s):  
Turbulence Modeling ◽  
Fluid Turbulence ◽  
Particle Flows ◽  
Two Fluid

Verification of filtered two-fluid models for gas-particle flows in risers

AIChE Journal ◽  
2010 ◽  
Vol 57 (10) ◽  
pp. 2691-2707 ◽  
Author(s):  
Yesim Igci ◽  
Sankaran Sundaresan
Keyword(s):  
Fluid Models ◽  
Particle Flows ◽  
Two Fluid

Review—Numerical Models for Dilute Gas-Particle Flows

1982 ◽  
Vol 104 (3) ◽  
pp. 297-303 ◽  
Author(s):  
C. T. Crowe
Keyword(s):  
Numerical Models ◽  
Model Development ◽  
Point Of View ◽  
One Dimensional ◽  
Advantages And Disadvantages ◽  
Dilute Gas ◽  
Particle Flows ◽  
Gaseous Flows ◽  
Droplet Flows ◽  
Two Fluid

The rapidly increasing capability of computers has led to the development of numerical models for gaseous flows and, in turn, gas-particle and gas-droplet flows. This paper reviews the essential features of gas-particle flows from the point of view of model development. Various models that have appeared for one-dimensional and two-dimensional flows are discussed. The advantages and disadvantages of the trajectory and two-fluid models are noted.

scholarly journals An Improved Multiscale Model for Dilute Turbulent Gas-Particle Flows Based on the Equilibration of Energy Concept

2005 ◽  
Author(s):  
Ying Xu ◽  
Shankar Subramaniam
Keyword(s):  
Fluid Phase ◽  
Multiscale Model ◽  
Stokes Number ◽  
Fluid Turbulence ◽  
Energy Concept ◽  
Particle Flows ◽  
Homogeneous Particle ◽  
Limiting Case ◽  
Physical Phenomena ◽  
Simple Flow

The objective of this study is to assess, and possibly improve, models for turbulent particle-laden flows. We begin by understanding the behavior of two existing models—one proposed by Simonin [Von Karman Institute of Fluid Dynamics Lecture Series, 1996], and the other by Ahmadi [Int. J. Multiphase Flow, 1990]—in the limiting case of statistically homogeneous particle-laden turbulent flow. The decay of particle and fluid phase turbulent kinetic energy (TKE) are compared with direct numerical simulation results. Even this simple flow poses a significant challenge to current models which have difficulties in reproducing important physical phenomena, such as the variation of TKE decay with particle Stokes number. Some of these problems can be traced to the model for the interphase TKE transfer timescale. A new model for the interphase transfer timescale is proposed that accounts for the interaction of particles with a range of fluid turbulence scales. A new multiphase turbulence model—the Equilibration of Energy Model (EEM)—is proposed, that incorporates this multiscale interphase transfer concept. The particle and fluid TKE evolution predicted by this new EEM model correctly reproduce the trends with particle Stokes number.

Quadrature-Based Moment Methods for Polydisperse Gas-Solids Flows

2010 ◽  
pp. 221-244 ◽  
Author(s):  
Alberto Passalacqua ◽  
Prakash Vedula ◽  
Rodney O. Fox
Keyword(s):  
Moment Method ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Particle Phase ◽  
Driven Cavity ◽  
Particle Flows ◽  
Coupling Procedure ◽  
Two Fluid Model ◽  
The Moment ◽  
Two Fluid

Classical Euler-Euler two-fluid models based on the kinetic theory of granular flows assume the particle phase to be dominated by collisions, even when the particle volume fraction is low and hence collisions are negligible. This leads to erroneous predictions of the particle-phase flow patterns and to the inability of such models to capture phenomena like particle trajectory crossing for finite Stokes numbers. To correctly predict the behavior of dilute gas-particle flows a more fundamental approach based on solving the Boltzmann kinetic equation is necessary to treat non-zero Knudsen-number and finite Stokes-number conditions. In this chapter an Eulerian quadrature-based moment method for the direct solution of the Boltzmann equation is adopted to describe the particle phase, and it is fully coupled with an Eulerian fluid solver to account for the two-way coupling between the phases. The solution algorithm for the moment transport equations derived in the quadrature-based moment method and the coupling procedure with a fluid solver are illustrated. The predictive capabilities of the method are shown considering a lid-driven cavity flow with particles at finite Stokes and Knudsen numbers, and comparing the results with both Euler-Euler two-fluid model predictions and with Euler-Lagrange simulations.

scholarly journals Scrape-off-layer current loops and floating potential in limited tokamak plasmas

2017 ◽  
Vol 83 (6) ◽  
Author(s):  
J. Loizu ◽  
J. A. Morales ◽  
F. D. Halpern ◽  
P. Ricci ◽  
P. Paruta
Keyword(s):  
Fluid Model ◽  
Radial Profile ◽  
Floating Potential ◽  
Tokamak Plasmas ◽  
Fluid Turbulence ◽  
Two Fluid Model ◽  
The One ◽  
Dipolar Structure ◽  
Two Fluid ◽  
Asymmetric Equilibrium

We investigate the question of how plasma currents circulate and close in the scrape-off-layer (SOL) of convection-limited tokamak plasmas. A simplified two-fluid model describes how currents must evacuate charge at the sheaths due to cross-field currents that are not divergence-free. These include turbulence-driven polarization currents and poloidally asymmetric equilibrium diamagnetic currents. The theory provides an estimate for the radial profile of the floating potential, which reveals a dipolar structure like the one observed experimentally. Simulations with a fluid turbulence code provide evidence for the predicted behaviour of currents and floating potential.

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