Extended Analytical Turbulent Diffusion Model for Particle Dispersion and Deposition in a Horizontal Pipe: Comparison with CFD Simulation

2011 ◽  
Vol 16 (3) ◽  
pp. 295-311 ◽  
Author(s):  
Alamgir Hossain ◽  
Jamal Naser ◽  
Monzur Imteaz
Keyword(s):  
Diffusion Model ◽  
Turbulent Diffusion ◽  
Cfd Simulation ◽  
Particle Dispersion ◽  
Horizontal Pipe

scholarly journals ANALYTICAL AND CFD INVESTIGATION OF TURBULENT DIFFUSION MODEL FOR PARTICLE DISPERSION AND DEPOSITION

1970 ◽  
Vol 40 (1) ◽  
pp. 39-53
Author(s):  
Alamgir Hossain ◽  
Jamal Naser
Keyword(s):  
Diffusion Model ◽  
Turbulent Diffusion ◽  
Particle Deposition ◽  
Fluid Velocity ◽  
Particle Diameter ◽  
Particle Dispersion ◽  
Homogeneous Distribution ◽  
Lower Velocity ◽  
Different Depths ◽  
Diffusion Particle

A 2D analytical turbulent diffusion model for particle dispersion and deposition at different heights across the pipe flow and circumferential deposition has been developed. This liquid-solid turbulent diffusion model presented in this paper has emanated from an existing gas-liquid turbulent diffusion model. Simultaneously a comprehensive 3D numerical investigation has been carried out to study the above making of multiphase mixture model available in Fluent 6.1. In both studies different particles sizes and densities were used. The deposition was studied as a function of particle diameter, density and fluid velocity. The deposition of particles, along the periphery of the wall and at different depths, was also investigated. Both studies showed that the deposition of heavier particles at the bottom of the pipe wall was found to be higher at lower velocities and lower at higher velocities. The lighter particles were found mostly suspended with homogeneous distribution. Smaller particles were also suspended with marginal higher concentration near the bottom of the wall. This marginal higher concentration of the smaller particles was found to be slightly pronounced for lower velocity. The larger particles clearly showed deposition near the bottom of the wall. These analogies of particles are well discussed with the ratio between free flight velocity and the gravitational settling velocity. Key Words: Multiphase flow, turbulence diffusion, particle deposition, horizontal flow.   doi: 10.3329/jme.v40i1.3472 Journal of Mechanical Engineering, Vol. ME40, No. 1, June 2009 39-53

scholarly journals Radial Transport and Momentum Exchange in an Axial Compressor

1992 ◽  
Author(s):  
Robert P. Dring
Keyword(s):  
Secondary Flow ◽  
Diffusion Model ◽  
Turbulent Diffusion ◽  
Flow Model ◽  
Axial Compressor ◽  
Momentum Exchange ◽  
Radial Transport ◽  
Axial Compressors ◽  
Mixing Coefficient ◽  
Spanwise Location

The objective of this work was to examine radial transport in axial compressors from two perspectives. The first was to compare the mixing coefficient based on a secondary flow model (using measured radial velocities) with that based on a turbulent diffusion model. The second was to use measured airfoil pressure forces and momentum changes to assess the validity of the assumption of diffusive radial transport which is common to both models. These examinations were carried out at both design and off-design conditions as well as for two rotor tip clearances. In general it was seen that radial mixing was strongest near the hub and that it increased dramatically at near-stall conditions. It was also seen that radial transport could cause large differences (≈ 100%) between the force on an airfoil and the change in momentum across the airfoil at the same spanwise location.

Near-Wall Turbulent Pressure Diffusion Modeling and Influence in Three-Dimensional Secondary Flows

2006 ◽  
Vol 129 (5) ◽  
pp. 634-642 ◽  
Author(s):  
E. Sauret ◽  
I. Vallet
Keyword(s):  
Diffusion Model ◽  
Turbulent Diffusion ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Moment Closure ◽  
Complex Flows ◽  
Diffusion Term ◽  
Pressure Diffusion ◽  
Turbulent Pressure ◽  
Near Wall

The purpose of this paper is to develop a second-moment closure with a near-wall turbulent pressure diffusion model for three-dimensional complex flows, and to evaluate the influence of the turbulent diffusion term on the prediction of detached and secondary flows. A complete turbulent diffusion model including a near-wall turbulent pressure diffusion closure for the slow part was developed based on the tensorial form of Lumley and included in a re-calibrated wall-normal-free Reynolds-stress model developed by Gerolymos and Vallet. The proposed model was validated against several one-, two, and three-dimensional complex flows.

Experimental Visualization and Numerical Simulation of Liquid-Gas Two-Phase Flows in a Horizontal Pipe

2017 ◽  
Author(s):  
Milad Darzi ◽  
Chanwoo Park
Keyword(s):  
Numerical Simulation ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Glass Tube ◽  
Flow Patterns ◽  
Two Phase Flows ◽  
Two Phase ◽  
Mixture Flow ◽  
Horizontal Pipe ◽  
Flow Rates

This paper presents the results of both visualization experiment and numerical simulation for two-phase (water-air mixture) flows in a horizontal tube. A visualization experimental setup was used to observe various two-phase flow patterns for different flow rates of water/air mixture flow in a glass tube of 12 mm in diameter. Total of 303 experimental data points were compared with Mandhane’s flow map. Most of the data for stratified, plug and slug flows were found to be in good agreement. However, annular flow was observed for relatively lower gas flow rates and also wavy flow occurred at relatively higher liquid flow rates in this experiment. A three-dimensional Computational Fluid Dynamics (CFD) simulation was performed using OpenFOAM employing “interFoam” as the solver to simulate the two-phase flows in horizontal pipe based on Volume-Of-Fluid (VOF) method. The simulated and experimentally observed flow patterns for the same set of superficial velocities shows acceptable similarities for stratified, wavy, plug, slug and annular flows. Also, the computed values of the void fraction and pressure drop for the numerical simulations shows reasonable agreement with well-known correlations in literature.

Numerical and Experimental Analysis of an Evaporation Cooler

2002 ◽  
Author(s):  
Robert Kickinger ◽  
Peter Wimmer ◽  
Helmut Leibinger
Keyword(s):  
Water Vapor ◽  
Phase Change ◽  
Cfd Simulation ◽  
Particle Dispersion ◽  
Scale Model ◽  
Water Droplets ◽  
Process Step ◽  
Image Velocimetry ◽  
Turbulent Particle Dispersion ◽  
Diffusion Convection

Evaporation coolers are commonly used to cool hot off-gases by injecting water droplets, which vaporize and thus cool the off-gas so that it can be filtered in the next process step. In this paper the flow and heat and mass transfer in a full scale industrial evaporation cooler are predicted with CFD methods. Three different configurations are compared and evaluated with respect to the flow homogeneity at the spray nozzle plane. In addition, the cold air flow without droplet evaporation in a lab scale model is investigated with CFD as well as PIV (particle image velocimetry) measurements and comparisons are given. In the CFD simulation model all phases involved (off-gas, water droplets, water vapor and dust) are considered. Water droplets and the dust phase are modelled by an Euler/Lagrangian dispersed phase model which allows for a phase change from water droplets to vapor. The mass fraction of water vapor is computed by a diffusion/convection equation. The equations of the Eulerian and Lagrangian phases are fully coupled (the influence of the dispersed phases on the continuous phases and the phase change from water droplets to vapor is realized by appropriate source terms in the Eulerian phase equations). Turbulent particle dispersion is modelled by a stochastic tracking technique.

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