Solid-Liquid Slurry Flow Through an Expansion in a Rectangular Duct

2013 ◽  
Author(s):  
Gianandrea Vittorio Messa ◽  
Stefano Malavasi
Keyword(s):  
Flow Field ◽  
Fluid Model ◽  
Experimental Tests ◽  
Sudden Expansion ◽  
Horizontal Pipe ◽  
Solids Concentration ◽  
Two Fluid Model ◽  
Liquid Slurry ◽  
Solid Liquid ◽  
Two Fluid

Duct flows of solid-liquid slurries are frequently encountered in many engineering applications. The literature about the behaviour of such mixtures in correspondence to hydraulic singularities — such as sudden variation of duct section, perforated plates and bar screens — is rather poor, despite they are integral part of the plants. The technical difficulties faced whilst performing experimental tests made CFD almost the only possible way to study the flow field in detail. In the present work the flow of sand-water mixtures through a sudden expansion in a rectangular horizontal duct is investigated by means of a two-fluid model. Due to the lack of experimental data available, a sensitivity analysis is performed to quantify the influence of the terms of the two-fluid model which proved negligible in the horizontal pipe case, topic of previous investigations. Computations were performed for either dilute or dense mixtures, in order to study the effect of the mean solids concentration on the flow field. Moreover, the effect of channel width is investigated to assess the validity of the hypothesis of two-dimensionality of the flow.

scholarly journals Computational investigation of liquid-solid slurry flow through an expansion in a rectangular duct

2014 ◽  
Vol 62 (3) ◽  
pp. 234-240 ◽  
Author(s):  
Gianandrea Vittorio Messa ◽  
Stefano Malavasi
Keyword(s):  
Volume Fraction ◽  
Particle Density ◽  
Fluid Model ◽  
Solid Volume Fraction ◽  
Solid Particles ◽  
Rectangular Duct ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Two Fluid Model ◽  
Two Fluid

Abstract The flow of a mixture of liquid and solid particles at medium and high volume fraction through an expansion in a rectangular duct is considered. In order to improve the modelling of the phenomenon with respect to a previous investigation (Messa and Malavasi, 2013), use is made of a two-fluid model specifically derived for dense flows that we developed and implemented in the PHOENICS code via user-defined subroutines. Due to the lack of experimental data, the two-fluid model was validated in the horizontal pipe case, reporting good agreement with measurements from different authors for fully-suspended flows. A 3D system is simulated in order to account for the effect of side walls. A wider range of the parameters characterizing the mixture (particle size, particle density, and delivered solid volume fraction) is considered. A parametric analysis is performed to investigate the role played by the key physical mechanisms on the development of the two-phase flow for different compositions of the mixture. The main focuses are the distribution of the particles in the system and the pressure recovery

Evaluation on the Application of Two-Fluid Multiphase Model to Supercavity

2013 ◽  
Vol 275-277 ◽  
pp. 417-428
Author(s):  
Jing Jun Zhou ◽  
Chun Peng Dong ◽  
Qing Rui Xiang
Keyword(s):  
Flow Field ◽  
Fluid Model ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Multiphase Model ◽  
Structure Of Flow ◽  
Natural Cavitation ◽  
Two Fluid Model ◽  
Ventilated Supercavity ◽  
Two Fluid

The lubrication of external liquid with supercavity has been the goals of specialists for many years. Either ventilated cavity or natural cavity is firstly related to multiphase flow. In this paper, in order to quantitatively predict the cavitating flow especially the ventilated supercavity and understand the structure of flow field in the cavity, two kinds of multiphase model including the homogeneous flow model and the two-fluid model were adopted separately. Besides, SST and DES turbulence model are used for steady and unsteady simulations. By comparing the simulating results with experimental results in water tunnel, the two-fluid model was proved to have the high accuracy in predicting the ventilated supercavity including the cavity shape and lift coefficient of the vehicle. On the other hand, for natural cavitation, the mixture model and the two-fluid model have little difference in predicting the pressure coefficient, however, the two-fluid model can give more detailed flow field.

Numerical Simulation Analysis of Fluid in the Semi-State within the Desulphurization Tower

2010 ◽  
Vol 118-120 ◽  
pp. 921-924 ◽  
Author(s):  
Wei Lin Guo ◽  
Chao He
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Circulating Fluidized Bed ◽  
Simulation Analysis ◽  
Fluid Model ◽  
Simulation Design ◽  
Tower Structure ◽  
Two Fluid Model ◽  
Major Equipment ◽  
Two Fluid

In this paper, the flow field in the desulphurization tower is studied deeply based on two-fluid model, particle dynamics theory and FLUENT. A numerical simulation analysis of fluid within the desulphurization tower is done and the desulphurization tower is the major equipment in the system. The simulation design and calculations show that the two-fluid model is reasonable to analyze the flow field. The simulation results show that smoke can form good reaction environment within the desulphurization tower. It is meaningful for the further optimization of designing desulphurization tower structure in the circulating fluidized bed system.

A CFD Study of an up- and a down-Pumping PBT Impeller in Solid-Liquid Stirred Tank

2011 ◽  
Vol 354-355 ◽  
pp. 696-700
Author(s):  
Gui Chao Wang ◽  
Shen Jie Zhou ◽  
Feng Ling Yang ◽  
Song Ying Chen
Keyword(s):  
Concentration Distribution ◽  
Reference Frames ◽  
Fluid Model ◽  
Stirred Tank ◽  
Pumping Mode ◽  
Multiple Reference Frames ◽  
Two Fluid Model ◽  
Solid Liquid ◽  
Multiple Reference ◽  
Two Fluid

Particles concentration distribution in a stirred tank with pitched blade turbine was investigated using computational fluid dynamics. The effect of the pumping mode on the turbulent flow and particles concentration distribution was studied. The turbulent solid-liquid flow in a stirred tank was simulated using a two-fluid model with standard k-ε turbulence model. The multiple reference frames approach was used to simulate impeller rotation. Results show that different pumping modes create different flow field which decide the characteristics of the mixing quality. A further detailed discussion about particles mixing at the bottom of the stirred tank was made. The computational model and the predicted results discussed here would be useful for understanding the solid-liquid mixing process.

Numerical Simulation on Characteristics of Dense-Phase Pneumatic Conveying in Horizontal Pipe

2009 ◽  
Vol 79-82 ◽  
pp. 1285-1288
Author(s):  
Zong Ming Liu ◽  
Hua Yi ◽  
Wei Lin Zhao ◽  
Xian Song Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Solid Phase ◽  
Fluid Model ◽  
Simulation Method ◽  
Pneumatic Conveying ◽  
Dense Phase ◽  
Horizontal Pipe ◽  
Two Fluid Model ◽  
Basic Characteristics

Numerical simulation of dense-phase pneumatic conveying flow field was carried out by using k-ε-ks-εs two-fluid model in horizontal pipe on the basis of kinetic theory of granular flow. The coupling issue between gas phase and solid phase was taken into account in the process of simulation. Such characteristics of flow field along pipe as pressure distribution, concentration distribution, gas and particle velocity distribution were obtained. The results of numerical simulation showed the tends of pressure, gas velocity, particle concentration in pipeline. The results of numerical simulation were compared with experimental results, and it showed that the simulation results were validated by the experimental data, which indicate that the model and the corresponding algorithm have higher accuracy and better prediction. Thus the numerical simulation method can reveal the basic characteristics of dense phase pneumatic conveying in horizontal pipe.

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