scholarly journals Comparison of porosity models for fluidized beds

2017 ◽  
Vol 2 (1) ◽  
pp. 74-83
Author(s):  
Sherko Ahmed Flamarz
Keyword(s):  
Fluidized Beds ◽  
Stokes Equations ◽  
Numerical Models ◽  
Column Height ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Equations ◽  
Time Stepping ◽  
Volume Method ◽  
Good Agreement

The paper describes a comparison between four numerical models of porosity, for better understanding the influence of porosity on the hydrodynamics (macroscopic and microscopic) behaviors of fluidized beds. The study has been done through an approach based on combine discrete-continuum to achieve the simulations. This approach deals with the modeling of the interactions between the fluid-solid. In which the discrete approach is used for localizing the position and velocity of each individual particles based on Newton’s 2nd law of motion, using a numerical time stepping scheme.  While the continuum approach is based on finite volume method, which is solved the fluid flow equations (Navier-Stokes equations). The geometry of fluidizing column was; column diameter (D=0.096 m) and column height (H=1 m). Glass grains were firstly deposited inside the column, and then subjected to the range of inlet water velocity (0-0.14 m.s-1). The results of simulations are point out those four models of porosity, achieved comparable results for simulating fluidized beds. The simulations results were compared and showed a good agreement and consistency with the experimental data in the literatures. In other hand, the simulations results revealed that the models of porosity, which based on the microscopic scale, are most reliable between the models of porosity.  However the differences between these models must be analyzed and kept in mind in order to select the appropriate porosity model. The results revealed that the porosity is an important parameter which effect on the hydrodynamics behavior of fluidized beds during the fluidization processes.

Numerical Investigation of Unsteady Incompressible 3D Turbulent Flow and Torque Transmission in Fluid Couplings

1994 ◽  
Author(s):  
L. Bal ◽  
A. Kost ◽  
M. Fiebig ◽  
N. K. Mitra
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
Flow Structures ◽  
Optimized Design ◽  
Navier Stokes Equations ◽  
Reference Flow ◽  
Torque Transmission ◽  
Adequate Understanding ◽  
Volume Method ◽  
Good Agreement

The adequate understanding of the flow structure in fluid couplings is necessary for the optimized design of such devices. Up to now, empiricism plays an important role in design. Detailed studies of the unsteady 3D flow and torque transmission in fluid couplings were rarely carried out. In this paper the unsteady Reynolds time-averaged Navier-Stokes equations coupled with the k-ε model have been solved by a finite-volume method. The calculations were done by using boundary-fitted grids with non-staggered variable arrangement for a rotating frame of reference. Flow structures in fluid couplings were obtained. The results give insights into the physical process of torque transmission. A comparsion of the calculated torque transimission with the experimental measurements in the literature shows good agreement for low slip.

Numerical Simulation on Undulatory Flow of Swimming Fish

2013 ◽  
Vol 353-356 ◽  
pp. 2545-2549
Author(s):  
Xu Zhang ◽  
Xiu Bin He
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Time Stepping ◽  
Dual Time Stepping ◽  
Straight Line ◽  
Volume Method ◽  
Undulatory Swimming

A numerical simulation is carried out to investigate the unsteady flows over a swimming fish. The three-dimensional incompressible Navier-Stokes equations are solved using the finite volume method with artificial compressibility and dual time stepping approaches on unstructured moving grid. A realistic fish-like body is modeled, which undergoes undulatory swimming in a straight line. Both inviscid and viscous flows have been simulated to study the flow structures.

Computational Investigation of Inlet Baffle Height on the Flow in a Rectangular Oil/Water Separator Tanks

2015 ◽  
Vol 802 ◽  
pp. 587-592
Author(s):  
Haitham A. Hussein ◽  
Rozi Abdullah ◽  
Md Azlin Md Said
Keyword(s):  
Stokes Equations ◽  
Experimental Tests ◽  
Navier Stokes ◽  
Computational Investigation ◽  
Navier Stokes Equations ◽  
Flow Equations ◽  
Water Separator ◽  
Oil Water ◽  
Volume Method ◽  
Maximum Removal

Gravity Separator Tanks are Used to Separate Oil from Water in Treatment Units. Achieving the Best Flow Uniformity in a Separator Tank will Improve the Maximum Removal Efficiency of Oil Globules from Water. in this Study, the Effect on Hydraulic Performance of Different Inlet Baffle Height inside a Tank was Investigated. some Experimental Tests were Done for Verification the Velocity Profile with Numerical Results Using ADV (Acoustic Doppler Velocimeter). A CFD Programme, Flow 3D Ver.10 was Used in which Finite Volume Method is Used for Solution of Water Flow Equations and RNG Turbulent Model with the Navier-Stokes Equations. the Volume of Fluid (VOF) Method was Used for Tracking of Free Surface in Simulation Program. the Results of the Numerical Simulation Show that the Separation Tank Performance can Be Improved by Altering the Geometry of the Tank and the Effects of Inlet Baffle Height on the Efficiency of the Separation Tank are Investigated via Assessment of the Circulation Zone Volume Variations, and the Uniformity of Flow Values in each Case.

Simulation of Unsteady Flow Around a Cylinder

2015 ◽  
Vol 3 (2) ◽  
pp. 28-49
Author(s):  
Ridha Alwan Ahmed
Keyword(s):  
Stokes Equations ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Mean Value ◽  
Navier Stokes ◽  
Cylinder Surface ◽  
Navier Stokes Equations ◽  
Flow Around A Cylinder ◽  
Numerical Grid ◽  
Good Agreement

       In this paper, the phenomena of vortex shedding from the circular cylinder surface has been studied at several Reynolds Numbers (40≤Re≤ 300).The 2D, unsteady, incompressible, Laminar flow, continuity and Navier Stokes equations have been solved numerically by using CFD Package FLUENT. In this package PISO algorithm is used in the pressure-velocity coupling.        The numerical grid is generated by using Gambit program. The velocity and pressure fields are obtained upstream and downstream of the cylinder at each time and it is also calculated the mean value of drag coefficient and value of lift coefficient .The results showed that the flow is strongly unsteady and unsymmetrical at Re>60. The results have been compared with the available experiments and a good agreement has been found between them

Numerical Modeling of Evolution of Boundary Between Incompressible Gas and Liquid in Two-Dimensional Region

2006 ◽  
Vol 4 ◽  
pp. 224-236
Author(s):  
A.S. Topolnikov
Keyword(s):  
Numerical Modeling ◽  
Interphase Boundary ◽  
Incompressible Liquid ◽  
Stokes Equations ◽  
Numerical Code ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Incompressible Media ◽  
Good Agreement

The paper is devoted to numerical modeling of Navier–Stokes equations for incompressible media in the case, when there exist gas and liquid inside the rectangular calculation region, which are separated by interphase boundary. The set of equations for incompressible liquid accounting for viscous, gravitational and surface (capillary) forces is solved by finite-difference scheme on the spaced grid, for description of interphase boundary the ideology of Level Set Method is used. By developed numerical code the set of hydrodynamic problems is solved, which describe the motion of two-phase incompressible media with interphase boundary. As a result of numerical simulation the solutions are obtained, which are in good agreement with existing analytical and experimental solutions.

scholarly journals Dynamics of Single Droplet Splashing on Liquid Film by Coupling FVM with VOF

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 841
Author(s):  
Yuzhen Jin ◽  
Huang Zhou ◽  
Linhang Zhu ◽  
Zeqing Li
Keyword(s):  
Liquid Film ◽  
Weber Number ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Single Droplet ◽  
Navier Stokes Equations ◽  
Volume Method ◽  
The Relationship

A three-dimensional numerical study of a single droplet splashing vertically on a liquid film is presented. The numerical method is based on the finite volume method (FVM) of Navier–Stokes equations coupled with the volume of fluid (VOF) method, and the adaptive local mesh refinement technology is adopted. It enables the liquid–gas interface to be tracked more accurately, and to be less computationally expensive. The relationship between the diameter of the free rim, the height of the crown with different numbers of collision Weber, and the thickness of the liquid film is explored. The results indicate that the crown height increases as the Weber number increases, and the diameter of the crown rim is inversely proportional to the collision Weber number. It can also be concluded that the dimensionless height of the crown decreases with the increase in the thickness of the dimensionless liquid film, which has little effect on the diameter of the crown rim during its growth.

On the Flow Fields of Inertial Impactors

1974 ◽  
Vol 96 (4) ◽  
pp. 394-400 ◽  
Author(s):  
V. A. Marple ◽  
B. Y. H. Liu ◽  
K. T. Whitby
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Relaxation Method ◽  
Water Model ◽  
Navier Stokes ◽  
Visualization Technique ◽  
Navier Stokes Equations ◽  
Theoretical Results ◽  
Plate Distance ◽  
Good Agreement

The flow field in an inertial impactor was studied experimentally with a water model by means of a flow visualization technique. The influence of such parameters as Reynolds number and jet-to-plate distance on the flow field was determined. The Navier-Stokes equations describing the laminar flow field in the impactor were solved numerically by means of a finite difference relaxation method. The theoretical results were found to be in good agreement with the empirical observations made with the water model.

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