A Numerical Study of the Laminar Viscous Incompressible Flow Through a Pipe Orifice

1978 ◽  
Vol 100 (4) ◽  
pp. 467-472 ◽  
Author(s):  
F. E. B. Nigro ◽  
A. B. Strong ◽  
S. A. Alpay
Keyword(s):  
Numerical Algorithm ◽  
Numerical Study ◽  
Equations Of Motion ◽  
Reynolds Numbers ◽  
Orifice Plate ◽  
Wide Range ◽  
Flow Through ◽  
Solution Efficiency ◽  
Plate Geometry ◽  
Initial Results

The present paper discusses a numerical algorithm for the solution of the steady flow of a viscous fluid through a pipe orifice which allows for considerable flexibility in the choice of orifice plate geometry. The results are compared to the data for a wide range of Reynolds numbers in the laminar regime and orifice/pipe diameter ratios for a 45 deg sharp edged orifice plate, a square edged orifice plate and a thin orifice plate. Based on the initial results presented here the numerical algorithm is deemed to provide a fast, accurate and relatively easy way of examining the effects of a wide variety of orifice plate geometries and flow situations. The solution efficiency is made possible by solving the equations of motion in general orthogonal coordinates.

CFD Simulation of Fluid Flow Through Porous Media: Application to Decomposed Gases Flow Through Foam Pattern in Lost Foam Casting

Materials ◽  
2003 ◽  
Author(s):  
Sayavur I. Bakhtiyarov ◽  
Ruel A. Overfelt
Keyword(s):  
Cfd Simulation ◽  
Reynolds Numbers ◽  
Phase Flow ◽  
Flow Through Porous Media ◽  
Foam Material ◽  
Element Analysis ◽  
Wide Range ◽  
Flow Through ◽  
Foam Pattern ◽  
Lost Foam

Numerical simulation of decomposed gases through foam pattern was conducted using finite element analysis. A new kinetic model is proposed for gaseos phase flow between molten metal and foam material. The computations were performed for a wide range of Reynolds numbers. The results of the simulations are compared with the experiemental data obtained in this study.

Calculation of the primary trajectories of seeds and other particles in strong winds

1983 ◽  
Vol 219 (1215) ◽  
pp. 217-217
Keyword(s):  
Equations Of Motion ◽  
Aerodynamic Resistance ◽  
Reynolds Numbers ◽  
Spherical Particles ◽  
Spores And Pollen ◽  
General Terms ◽  
Wide Range ◽  
Strong Winds ◽  
Dispersal Distances ◽  
Enormous Number

The movement of variously dense spherical particles representing a variety of seeds, fruits, spores and pollen, and released from rest into arbitrary winds and a gravitational field is discussed in general terms that account in detail for changes in the quasi-static aerodynamic resistance to motion experienced by such particles during aerial flight. A hybrid analytical-empirical law is established which describes this resistance fairly accurately for particle Reynolds numbers in the range 0—60 000 and that allows for the numerical integration of the equations of motion so as to cover a very wide range of flight conditions. This makes possible the provision of a set of four-parameter universal range tables from which the dispersal distances for an enormous number of practical cases may be estimated. One particular case of particle movement in a region of pseudo-thermal convection is also discussed and this shows how a marked degree of deposition concentration may be induced in some circumstances by such a flow. Botanists and ecologists concerned with seed and particle dispersal in the environment may find the universal range tables of particular interest and use. This is because the tables obviate the need for the integration of the equations of motion when dealing with individual cases and permit an estimation of range purely on the basis of the specified quantities of particle size, density and altitude of release, atmospheric wind speed, density and viscosity, and the acceleration due to gravity.

Numerical Study on Mixing of Two Fluids With Modified Tesla Structure

2009 ◽  
Author(s):  
Shakhawat Hossain ◽  
Mubashshir Ahmad Ansari ◽  
Afzal Husain ◽  
Kwang-Yong Kim
Keyword(s):  
Vortical Structure ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
The Other ◽  
Channel Width ◽  
Geometrical Parameters ◽  
Fluid Stream ◽  
Mixing Performance ◽  
Two Fluids ◽  
Wide Range

In this study, a parametric investigation on mixing of two fluids in a modified Tesla microchannel, has been preformed. Modified Tesla micromixer applies both flow separation and vortices string principles to enhance the mixing. The fluid stream splits into two sub-streams and one of them mixes with the other again at the exit of the Tesla unit. Analyses of mixing and flow field have been carried out for a wide range of Reynolds number from 0.05 to 40. Mixing performance and pressure drop characteristics with two geometrical parameters, i.e, ratio of the diffuser gap to channel width (h/w) and ratio of the curved gap to the channel width (s/w), have been analyzed at six different Reynolds numbers. The vortical structure of the flow has been analyzed to explain mixing performance. The sensitivity analysis reveals that mixing is more sensitive s/w, than the h/w.

Analysis of a Novel Y-Y Micromixer for Mixing at a Wide Range of Reynolds Numbers

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Vladimir Viktorov ◽  
Carmen Visconte ◽  
Md Readul Mahmud
Keyword(s):  
Three Dimensional ◽  
Interfacial Area ◽  
Reynolds Numbers ◽  
Mixing Efficiency ◽  
Change Of Direction ◽  
Analysis Technique ◽  
Wide Range ◽  
Passive Micromixer ◽  
In Series ◽  
Flow Through

A novel passive micromixer, denoted as the Y-Y mixer, based on split-and-recombine (SAR) principle is proposed and studied both experimentally and numerically over Reynolds numbers ranging from 1 to 100. Two species are supplied to a prototype via a Y inlet, and flow through four identical elements repeated in series; the width of the mixing channel varies from 0.4 to 0.6 mm, while depth is 0.4 mm. An image analysis technique was used to evaluate mixture homogeneity at four target areas along the mixer. Numerical simulations were found to be a useful support for observing the complex three-dimensional flow inside the channels. Comparison with a known mixer, the tear-drop one, based on the same SAR principle, was also performed, to have a point of reference for evaluating performances. A good agreement was found between numerical and experimental results. Over the examined range of Reynolds numbers Re, the Y-Y micromixer showed at its exit an almost flat mixing characteristic, with a mixing efficiency higher than 0.9; conversely, the tear-drop mixer showed a relevant decrease of efficiency at the midrange. The good performance of the Y-Y micromixer is due to the three-dimensional 90 deg change of direction that occurs in its channel geometry, which causes a fluid swirling already at the midrange of Reynolds numbers. Consequently, the fluid path is lengthened and the interfacial area of species is increased, compensating for the residence time reduction.

A numerical study of three-dimensional turbulent channel flow at large Reynolds numbers

1970 ◽  
Vol 41 (2) ◽  
pp. 453-480 ◽  
Author(s):  
James W. Deardorff
Keyword(s):  
Scale Effects ◽  
Numerical Study ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Turbulent Channel Flow ◽  
Reynolds Numbers ◽  
Numerical Approach ◽  
Uniform Grid ◽  
Turbulence Energy ◽  
Vertical Diffusion

The three-dimensional, primitive equations of motion have been integrated numerically in time for the case of turbulent, plane Poiseuille flow at very large Reynolds numbers. A total of 6720 uniform grid intervals were used, with sub-grid scale effects simulated with eddy coefficients proportional to the local velocity deformation. The agreement of calculated statistics against those measured by Laufer ranges from good to marginal. The eddy shapes are examined, and only theu-component, longitudinal eddies are found to be elongated in the downstream direction. However, the lateralveddies have distinct downstream tilts. The turbulence energy balance is examined, including the separate effects of vertical diffusion of pressure and local kinetic energy.It is concluded that the numerical approach to the problem of turbulence at large Reynolds numbers is already profitable, with increased accuracy to be expected with modest increase of numerical resolution.

scholarly journals Quantifying Compressibility and Slip in Multiparticle Collision (MPC) Flow Through a Local Constriction

2021 ◽  
Author(s):  
Tahmina Akhter ◽  
Katrin Rohlf
Keyword(s):  
Stokes Equations ◽  
Equations Of Motion ◽  
Wall Slip ◽  
Reynolds Numbers ◽  
Ideal Gas ◽  
Navier Stokes ◽  
Numerical Work ◽  
Navier Stokes Equations ◽  
Flow Through ◽  
Generalized Boundary Condition

The flow of a compressible fluid with slip through a cylinder with an asymmetric local constriction has been considered both numerically, as well as analytically. For the numerical work, a particle-based method whose dynamics is governed by the multiparticle collision (MPC) rule has been used together with a generalized boundary condition that allows for slip at the wall. Since it is well known that an MPC system corresponds to an ideal gas and behaves like a compressible, viscous flow on average, an approximate analytical solution has been derived from the compressible Navier–Stokes equations of motion coupled to an ideal gas equation of state using the Karman–Pohlhausen method. The constriction is assumed to have a polynomial form, and the location of maximum constriction is varied throughout the constricted portion of the cylinder. Results for centerline densities and centerline velocities have been compared for various Reynolds numbers, Mach numbers, wall slip values and flow geometries.

Simulation of Fluid Flow Through a Granular Bed

2006 ◽  
Author(s):  
Arezou Jafari ◽  
S. Mohammad Mousavi
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Packed Bed ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Wide Range ◽  
Duct Geometry ◽  
Flow Through

Numerical study of flow through random packing of non-overlapping spheres in a cylindrical geometry is investigated. Dimensionless pressure drop has been studied for a fluid through the porous media at moderate Reynolds numbers (based on pore permeability and interstitial fluid velocity), and numerical solution of Navier-Stokes equations in three dimensional porous packed bed illustrated in excellent agreement with those reported by Macdonald [1979] in the range of Reynolds number studied. The results compare to the previous work (Soleymani et al., 2002) show more accurate conclusion because the problem of channeling in a duct geometry. By injection of solute into the system, the dispersivity over a wide range of flow rate has been investigated. It is shown that the lateral fluid dispersion coefficients can be calculated by comparing the concentration profiles of solute obtained by numerical simulations and those derived analytically by solving the macroscopic dispersion equation for the present geometry.

scholarly journals Quantifying Compressibility and Slip in Multiparticle Collision (MPC) Flow Through a Local Constriction

2021 ◽  
Author(s):  
Tahmina Akhter ◽  
Katrin Rohlf
Keyword(s):  
Stokes Equations ◽  
Equations Of Motion ◽  
Wall Slip ◽  
Reynolds Numbers ◽  
Ideal Gas ◽  
Navier Stokes ◽  
Numerical Work ◽  
Navier Stokes Equations ◽  
Flow Through ◽  
Generalized Boundary Condition

The flow of a compressible fluid with slip through a cylinder with an asymmetric local constriction has been considered both numerically, as well as analytically. For the numerical work, a particle-based method whose dynamics is governed by the multiparticle collision (MPC) rule has been used together with a generalized boundary condition that allows for slip at the wall. Since it is well known that an MPC system corresponds to an ideal gas and behaves like a compressible, viscous flow on average, an approximate analytical solution has been derived from the compressible Navier–Stokes equations of motion coupled to an ideal gas equation of state using the Karman–Pohlhausen method. The constriction is assumed to have a polynomial form, and the location of maximum constriction is varied throughout the constricted portion of the cylinder. Results for centerline densities and centerline velocities have been compared for various Reynolds numbers, Mach numbers, wall slip values and flow geometries.

Numerical Simulations of Turbulent Flow through an Orifice Plate in a Pipe

2020 ◽  
pp. 1-11
Author(s):  
Guang Yin ◽  
Bjørnar Nitter ◽  
Muk Chen Ong
Keyword(s):  
Turbulent Flow ◽  
Numerical Simulations ◽  
Flow Velocity ◽  
Flow Rate ◽  
Reynolds Numbers ◽  
Streamwise Velocity ◽  
Orifice Plate ◽  
Pipe Diameter ◽  
Orifice Diameter ◽  
Flow Through

Abstract Orifice flow meters are widely used in industries to measure the flow rate in pipelines. The flow rate inside the pipe can be calculated using the relationship between the flow velocity and the pressure drop across the orifice plate. In the present study, numerical simulations have been carried out using three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations combined with the k-ω SST turbulence model to thoroughly investigate the turbulent flow through a circular square-edged orifice with various orifice plate thicknesses and orifice diameters inside a pipe at different Reynolds numbers ranging from 2500 to 40000. The orifice thickness to pipe diameter ratio (t) varies between 0.125 and 2 and the orifice diameter to pipe diameter (ß) varies between 0.25 and 0.75. The resulting centerline profiles of the streamwise velocity and pressure of the present study are compared with the previous published numerical results and experimental data as the validation study. The effects of Reynolds numbers and orifice geometries on the pressure, the flow velocity and vorticity distribution in the orifice are discussed in detail. It is found that for the fixed ß, the discharge coefficient increases with the increasing t and the vortical structure inside the orifice is separated into two regions located at the two edges of the orifice. For the fixed t, the size of the large recirculation motions behind the plate increases and the vorticity around the plate becomes stronger with the decreasing ß.

Fluid Flow Bifurcation in Micro-Channels

2003 ◽  
Author(s):  
S. Patel ◽  
D. Drikakis
Keyword(s):  
Fluid Flow ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Flow Transition ◽  
Incompressible Fluid Flow ◽  
Low Reynolds Numbers ◽  
Multigrid Algorithm ◽  
Micro Channels ◽  
Micro Flows ◽  
Flow Through

The paper presents a numerical study of incompressible fluid flow through micro-channels. Using a high-resolution numerical method (second-order accurate) in conjunction with a non-linear multigrid algorithm and the pseudo-compressibility approach, we have investigated micro-flows through straight channels, as well as through a sudden contraction-expansion geometry. For the straight channel geometry, the computational results are in reasonable agreement with the experimental data for various low Reynolds numbers. For the contraction-expansion geometry, the results reveal the flow transition to instability. This is manifested in the form of asymmetric separation downstream of the expansion.

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