Laminar Fluid Flow in a Planar 90 Degree Bifurcation With and Without a Protruding Branching Duct

1996 ◽  
Vol 118 (1) ◽  
pp. 81-84 ◽  
Author(s):  
T. G. Travers ◽  
W. M. Worek
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Fluid Flow ◽  
Velocity Field ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Flow Field ◽  
Numerical Study ◽  
Main Duct

The laminar flow field in a planar, ninety degree bifurcation is examined. This numerical study uses the computational-fluid-dynamics software Fluent Version 4.11. First, the velocity field in a bifurcation without a protruding branching duct is modeled, and the results are successfully compared to experimental data. Next, the flow field is studied in bifurcations that have branching ducts that protrude into the main duct. The velocity field and pressure drop are documented, and are found to be strongly influenced by the extent of the branching duct protrusion.

A Numerical Study of the Flow and Pollutant Dispersion in Valley-River Urban

2013 ◽  
Vol 645 ◽  
pp. 208-216
Author(s):  
Rong Huang ◽  
Naiang Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Numerical Study ◽  
Concentration Field ◽  
Pollutant Dispersion ◽  
Northwest China ◽  
Navier Stokes ◽  
The Impact ◽  
Valley City

Air flow and pollutant dispersion characteristics in a real valley city are studied under the real boundary condition. The 3D computational fluid dynamics using Reynolds-averaged Navier-Stokes modeling was carried out in Lanzhou which is a typical valley city in Northwest, China. The standard κ­-ε turbulence model as a simplified computational fluid dynamics model is used to provide moderately fast simulations of turbulent airflow in an urban environment. The modeled flow field indicated that the geometry, wind direction and source location had a significant effects on the flow field. The flow shows the funnelling is rather obvious when the wind flow through the narrow area in the middle of the city. It is obvious that in the high-altitude region, due to the impact of high and low differential pressure and terrain, SO2 and NO2 formed two cyclic concentration field in the dispersion process.

scholarly journals Effects of convergent–divergent vortex finders on the performance of cyclone separators using computational fluid dynamics simulations

SIMULATION ◽  
2019 ◽  
Vol 96 (1) ◽  
pp. 31-42
Author(s):  
Vikash Kumar ◽  
Kailash Jha
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Collection Efficiency ◽  
Flow Simulation ◽  
Reynolds Stress Model ◽  
Continuity Equations ◽  
Vortex Finder ◽  
Uniform Diameter

This study investigates the effect of convergent–divergent vortex finders on the performance of cyclone separators, which is measured in terms of pressure drop and collection efficiency. Six cyclone models (two with uniform diameter and four with convergent–divergent vortex finders) were numerically simulated. The numerical simulations have been carried out using the commercial computational fluid dynamics code (CFD) Fluent v15. The simulation procedure has been validated using experimental data from the published literature where a good agreement between the numerical results and the experimental data is seen. A grid independence test has been carried out by using two levels of grids for correctness of our simulation. The Reynolds averaged Navier–Stokes (RANS) and continuity equations have been solved for the flow simulation. The Reynolds stress model is used for modeling the stress tensor and closing the RANS equations. The results show that a convergent–divergent vortex finder is capable of producing better performance (pressure drop and collection efficiency) than the uniform diameter cyclones. Only one performance parameter can be improved in uniform diameter cyclones. In comparison to the standard uniform vortex finder cyclones, the convergent–divergent vortex finder improves the pressure drop by 6% and also reduces the cut-size to 1.4 from 1.6 µm. It is further seen that decreasing the throat area or increasing only the lower diameter of the vortex finder causes the performance to degrade. This study proves that convergent–divergent instead of uniform diameter vortex finders can be used in gas cyclones for obtaining a better performance with the same geometry.

A Numerical Study of Flow Field in a Hydrocyclone for Potash Ore Desliming

2013 ◽  
Vol 448-453 ◽  
pp. 3847-3850
Author(s):  
Da Li ◽  
Fang Qin Cheng ◽  
Jian Feng Li ◽  
Yun Shan Guan
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Numerical Study ◽  
Numerical Approach ◽  
Basic Information ◽  
Feed Composition ◽  
Accurate Design ◽  
Computational Fluid Dynamics Cfd

Despite the widespread use of hydrocyclone in the process of potash ore desliming, its accurate design is often difficult because the feed composition is complicated and the viscosity is high in the brine system. In this study, a numerical approach based on computational fluid dynamics (CFD) was performed to describe the flow field. The numerical simulation of flow pattern in hydrocyclones for potash ore desliming was presented. Some basic information concerning the velocity and pressure distribution is given, and the results can be used as the fundamental basis for its design.

Comparison of Particle-Wall Interaction Boundary Conditions in the Prediction of Cyclone Collection Efficiency in Computational Fluid Dynamics (CFD) Modeling

2010 ◽  
Vol 660-661 ◽  
pp. 158-163
Author(s):  
M.Ramirez Valverde ◽  
José Renato Coury ◽  
José Antônio Silveira Gonçalves
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Collection Efficiency ◽  
Cfd Modeling ◽  
Wall Boundary Conditions ◽  
Computational Fluid Dynamics Cfd ◽  
Wall Interaction

In recent years, many computational fluid dynamics (CFD) studies have appeared attempting to predict cyclone pressure drop and collection efficiency. While these studies have been able to predict pressure drop well, they have been only moderately successful in predicting collection efficiency. Part of the reason for this failure has been attributed to the relatively simple wall boundary conditions implemented in the commercially available CFD software, which are not capable of accurately describing the complex particle-wall interaction present in a cyclone. According, researches have proposed a number of different boundary conditions in order to improve the model performance. This work implemented the critical velocity boundary condition through a user defined function (UDF) in the Fluent software and compared its predictions both with experimental data and with the predictions obtained when using Fluent’s built-in boundary conditions. Experimental data was obtained from eight laboratory scale cyclones with varying geometric ratios. The CFD simulations were made using the software Fluent 6.3.26.

scholarly journals Numerical Study of Flow-Induced Vibrations of Multiple Flexibly-Mounted Cylinders in Triangular Array

2018 ◽  
Vol 55 (5) ◽  
pp. 43-53
Author(s):  
S. Upnere
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Flow ◽  
Open Source ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Triangular Array ◽  
Rod Bundle ◽  
Flow Induced Vibrations ◽  
Oscillation Characteristics

Abstract The paper presents the numerical study of vibrating multiple flexibly-mounted cylinders in a triangular rod bundle. Behavioural trends of six different clusters of oscillating rods have been analysed. The influence of neighbour cylinders on the central cylinder oscillation characteristics is analysed. Finite volume solver of open source computational fluid dynamics is used to calculate the fluid flow in the channel with the cylinder array. Built-in six degree-of-freedoms solver is utilised to simulate cylinder movement. Oscillating cylinders have two degrees-of-freedom. The obtained results are compared with numerical results available in the literature.

Pressure Drop Predictions in Microfibrous Materials Using Computational Fluid Dynamics

2008 ◽  
Vol 130 (7) ◽  
Author(s):  
Ravi K. Duggirala ◽  
Christopher J. Roy ◽  
S. M. Saeidi ◽  
Jay M. Khodadadi ◽  
Don R. Cahela ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Void Fraction ◽  
Minor Effect ◽  
Packed Beds ◽  
Void Fractions ◽  
Face Velocity ◽  
Experimental Pressure

Three-dimensional computational fluid dynamics simulations are performed for the flow of air through microfibrous materials for void fractions of 0.41 and 0.47 and face velocities ranging between 0.04ms and 1.29m∕s. The microfibrous materials consist of activated carbon powder with diameters of 137×10−6m entrapped in a matrix of cylindrical fibers with diameters of 8×10−6m. These sintered microfibrous materials are a new class of patented materials with properties that are advantageous compared to traditional packed beds or monoliths. Microfibrous materials have demonstrated enhanced heat and mass transfer compared to packed beds of particles of similar dimensions. In this paper, the simulations are used to predict the pressure drop per unit length through the materials and to analyze the details of the flow that are difficult to interrogate experimentally. Various geometric approximations are employed in order to allow the simulations to be performed in an efficient manner. The Knudsen number, defined as the ratio of the mean free path between molecular collisions to the fiber diameter, is 0.011; thus, velocity-slip boundary conditions are employed and shown to have only a minor effect on the pressure drop predictions. Significant effort is made to estimate numerical errors associated with the discretization process, and these errors are shown to be negligible (less than 3%). The computational predictions for pressure drop are compared to available experimental data as well as to two theory-based correlations: Ergun’s equation and the porous media permeability equation. The agreement between the simulations and the experiments is within 30% and is reasonable considering the significant geometric approximations employed. The errors in the simulations and correlations with respect to experimental data exhibit the same trend with face velocity for both void fractions. This consistent trend suggests the presence of experimental bias errors that correlate with the face velocity. The simulations generally underpredict the experimental pressure drop for the low void fraction case and overpredict the experimental pressure drop for the high void fraction case.

Using Computational Fluid Dynamics (CFD) for Evaluation of Fluid Flow Through a Gate Valve

2012 ◽  
Vol 8 (4) ◽  
Author(s):  
Pedro Esteves Duarte Augusto ◽  
Marcelo Cristianini
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Gate Valve ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Type Equation ◽  
Pharmaceutical Products ◽  
Computational Fluid Dynamics Cfd

Abstract Gate valves are the most common valve in industrial plants. However, there is no work in the literature regarding the use of computational fluid dynamics (CFD) to evaluate the fluid flow characteristics and pressure drop in gate valves. The present work evaluated the fluid flow and pressure drop through a commercial gate valve using CFD. The obtained values for the pressure loss coefficient (k) are in accordance to those described in the literature and a power type equation could be used for modeling it as function of the Reynolds Number. Fluid flow behavior through the gate valve highlighted the flow recirculation and stagnant areas, being critical for food and pharmaceutical products processing. The obtained results reinforce the advantages in using CFD as a tool for the engineering evaluation of fluid processes.

Performance analysis of reciprocating compressors through computational fluid dynamics

2008 ◽  
Vol 222 (4) ◽  
pp. 183-192 ◽  
Author(s):  
E L L Pereira ◽  
C J Deschamps ◽  
F A Ribas
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Numerical Analysis ◽  
Performance Analysis ◽  
Flow Field ◽  
Three Dimensional ◽  
Time Dependent ◽  
Valve Dynamics ◽  
Dependent Flow

An experimentally validated numerical analysis of reciprocating refrigeration compressors is presented. The finite-volume methodology is adopted to solve the flow field and a one-degree-of-freedom model is used to describe the valve dynamics. The variation of the computation domain, associated with the valve and piston displacements, is taken into account and the time-dependent flow field and the valve dynamics are coupled and solved simultaneously. The three-dimensional formulation considered in the analysis allowed the simulation of actual suction and discharge muffler geometries. Numerical results were validated with reference to experimental data for valve displacement and pressure in the suction and compression chambers obtained in a calorimeter facility. A study was carried out to identify the contributions of mufflers and valves to the compressor thermodynamic losses.

scholarly journals Numerical study of fluid behavior on protruding shapes within the inlet part of pressurized membrane module using computational fluid dynamics

2019 ◽  
Vol 25 (4) ◽  
pp. 498-505 ◽  
Author(s):  
Changkyoo Choi ◽  
Chulmin Lee ◽  
No-Suk Park ◽  
In S. Kim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Flow ◽  
Numerical Study ◽  
Fluid Velocity ◽  
Flow Distribution ◽  
Membrane Module ◽  
Cross Sectional ◽  
Fluid Behavior ◽  
Uniform Flow Distribution

This study analyzes the velocity and pressure incurred by protruding shapes installed within the inlet part of a pressurized membrane module during operation to determine the fluid flow distribution. In this paper, to find the flow distribution within a module, it investigates the velocity and pressure values at cross-sectional and outlet planes, and 9 sections classified on outlet plane using computational fluid dynamics. From the Reynolds number (Re), the fluid flow was estimated to be turbulent when the Re exceeded 4,000. In the vertical cross-sectional plane, shape 4 and 6 (round-type protrusion) showed the relatively high velocity of 0.535 m/s and 0.558 m/s, respectively, indicating a uniform flow distribution. From the velocity and pressure at the outlet, shape 4 also displayed a relatively uniform fluid velocity and pressure, indicating that fluid from the inlet rapidly and uniformly reached the outlet, however, from detailed data of velocity, pressure and flowrate obtained from 9 sections at the outlet, shape 6 revealed the low standard deviations for each section. Therefore, shape 6 was deemed to induce the ideal flow, since it maintained a uniform pressure, velocity and flowrate distribution.

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