Analysis of Fluid Flow Under a Grinding Wheel

1991 ◽  
Vol 113 (2) ◽  
pp. 190-197 ◽  
Author(s):  
M. R. Schumack ◽  
Jin-Bok Chung ◽  
W. W. Schultz ◽  
E. Kannatey-Asibu
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Lubrication Theory ◽  
Grinding Wheel ◽  
Perturbation Scheme ◽  
Moderate Reynolds Number ◽  
Reynolds Number Flows ◽  
Good Agreement

Fluid flow under a grinding wheel is modeled using a perturbation scheme. In this initial effort to understand the flow characteristics, we concentrate on the case of a smooth wheel with slight clearance between the wheel and workpiece. The solution at lowest order is that given by standard lubrication theory. Higher-order terms correct for inertial and two-dimensional effects. Experimental and analytical pressure profiles are compared to test the validity of the model. Lubrication theory provides good agreement with low Reynolds number flows; the perturbation scheme provides reasonable agreement with moderate Reynolds number flows but fails at high Reynolds numbers. Results from experiments demonstrate that the ignored upstream and downstream conditions significantly affect the flow characteristics, implying that only a model based on the fully two- (or three-) dimensional Navier-Stokes equations will accurately predict the flow. We make one comparison between an experiment with a grinding wheel and the model incorporating a one-dimensional sinusoidal roughness term. For this case, lubrication theory surprisingly provides good agreement with experiment.

Numerical Simulation of Flow in a Wavy Wall Microchannel Using Immersed Boundary Method

2020 ◽  
Vol 13 (2) ◽  
pp. 118-125
Author(s):  
Mithun Kanchan ◽  
Ranjith Maniyeri
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Immersed Boundary Method ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Immersed Boundary ◽  
Solid Boundary ◽  
Wavy Wall ◽  
Dirac Delta ◽  
Boundary Method

Background: Fluid flow in microchannels is restricted to low Reynolds number regimes and hence inducing chaotic mixing in such devices is a major challenge. Over the years, the Immersed Boundary Method (IBM) has proved its ability in handling complex fluid-structure interaction problems. Objectives: Inspired by recent patents in microchannel mixing devices, we study passive mixing effects by performing two-dimensional numerical simulations of wavy wall in channel flow using IBM. Methods: The continuity and Navier-Stokes equations governing the flow are solved by fractional step based finite volume method on a staggered Cartesian grid system. Fluid variables are described by Eulerian coordinates and solid boundary by Lagrangian coordinates. A four-point Dirac delta function is used to couple both the coordinate variables. A momentum forcing term is added to the governing equation in order to impose the no-slip boundary condition between the wavy wall and fluid interface. Results: Parametric study is carried out to analyze the fluid flow characteristics by varying amplitude and wavelength of wavy wall configurations for different Reynolds number. Conclusion: Configurations of wavy wall microchannels having a higher amplitude and lower wavelengths show optimum results for mixing applications.

Fluid Flow Characteristics Around a Pair of Diamond-Shaped Cylinders in Side-by-Side and Tandem Arrangements

2011 ◽  
Author(s):  
Shuichi Torii ◽  
Noritugu Ueda ◽  
Zijie Lin
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Time History ◽  
Flow Patterns ◽  
Separation Distance ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Gap Spacing

The present study deals with unsteady laminar fluid flow phenomena around a pair of diamond-shaped cylinders in free stream. Emphasis is placed on the effects of the Reynolds number, Re, and the ratio of cylinder separation distance to length of diamond-shaped cylinder, s/d, on the flow patterns in side-by-side and tandem arrangements. The Navier-Stokes equations are discretized using finite difference method to determine the time history of velocity vector in the flow field. The Reynolds numbers, Re, is ranged from 30 to 300 and gap spacing, s/d, is varied from 0.0 to 2.5 for side-by-side and 0.0 to 5.0 for tandem, respectively. The results are compared with the experimental results with the aid of flow visualization method. The study discloses that (i) the generations of Karman vortex streets behind the diamond-shaped cylinders are intensified with an increase in the Reynolds number, (ii) the categorized flow patterns in the wake region of the diamond-shaped islands are affected by s/d, and (iii) the vortex shedding frequency in the wake of diamond-shaped cylinders depends on both the gap spacing and the formation of the vortices.

Cartesian Grid Method for Moderate-Reynolds-Number Flows Around Complex Moving Objects

AIAA Journal ◽  
2005 ◽  
Vol 43 (1) ◽  
pp. 76-86 ◽  
Author(s):  
Jo-Einar Emblemsvag ◽  
Ryuta Suzuki ◽  
Graham V. Candler
Keyword(s):  
Reynolds Number ◽  
Moving Objects ◽  
Grid Method ◽  
Cartesian Grid ◽  
Cartesian Grid Method ◽  
Moderate Reynolds Number ◽  
Reynolds Number Flows

Fluid Flow Characteristics of a Confined Slot Jet Without or With a Target Surface

2005 ◽  
Author(s):  
L. K. Liu ◽  
C. J. Fang ◽  
M. C. Wu ◽  
C. Y. Lee ◽  
Y. H. Hung
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Fluid Velocity ◽  
Flow Characteristics ◽  
Target Surface ◽  
Streamwise Velocity ◽  
Separation Distance ◽  
Experimental Investigations ◽  
Flow Parameters ◽  
Fluid Flow Characteristics

A series of experimental investigations with a stringent measurement method on the fluid flow characteristics of slot jet without or with a target surface have been successfully conducted. From all the fluid velocity data measured in the present study, the experimental conditions have been verified to be spanwise-symmetrically maintained and the results have been achieved in a spanwise-symmetric form. Three types of jet configuration without or with target surface are investigated: (A) Confined Slot Jet without Target Surfaces – the fluid flow parameters studied in the present investigation is the jet Reynolds number (ReD). Its ranges are ReD=506-1517. (B) Confined Slot Jet with Smooth Surfaces – the fluid flow parameters studied in the present investigation include the ratio of jet separation distance (H) to nozzle width (W) and the jet Reynolds number (ReD). The ranges of the relevant parameters are H/W=2–10 and ReD=504–1526. (C) Confined Slot Jet with Extended Surfaces – the fluid flow parameters studied include the ratio of jet separation distance (H) to nozzle width (W), the Reynolds number (ReD) and the ratio of extended surface height (Hes) to nozzle width (W). Their ranges are H/W=3–10, Hes/W=0.74-3.40 and ReD=501–1547. The flow characteristics such as the local mean streamwise velocity distribution, mean streamwise velocity decay along jet centerline, local jet turbulence intensity distribution, and turbulence intensities along jet centerline have been presented and discussed in the study.

Simulation of Fluid Flow in a Microchannel at Low Reynolds Number Using Dissipative Particle Dynamics

2018 ◽  
Author(s):  
Waqas Waheed ◽  
Anas Alazzam ◽  
Ashraf N. Al Khateeb ◽  
Eiyad Abu Nada
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Velocity Profile ◽  
Drag Coefficient ◽  
Dissipative Particle Dynamics ◽  
Particle Dynamics ◽  
Published Data ◽  
Two Dimensional ◽  
Close Match ◽  
Good Agreement

In this paper, a two-dimensional Dissipative Particle Dynamics (DPD) technique to simulate the poiseuille flow in a microchannel is developed using an in-house code. The calculated Reynolds number is reduced via adjusting the DPD parameters. The obtained velocity profile is compared with the analytical results and a good agreement is found. The drag force and the drag coefficient on a stationary cylinder exerted by the fluid particles are obtained using the developed DPD code. The calculated drag coefficient exhibits a close match with already published data in the literature.

Analysis of heat transfer and fluid flow of a slot jet impinging on a confined concave surface with various curvature and small jet to target spacing

2019 ◽  
Vol 29 (8) ◽  
pp. 2885-2910 ◽  
Author(s):  
Dandan Qiu ◽  
Lei Luo ◽  
Songtao Wang ◽  
Bengt Ake Sunden ◽  
Xinhong Zhang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Thermal Performance ◽  
Flow Characteristics ◽  
Target Surface ◽  
Surface Curvature ◽  
Content Type ◽  
Curvature Effects ◽  
Target Spacing

Purpose This study aims to focus on the surface curvature, jet to target spacing and jet Reynolds number effects on the heat transfer and fluid flow characteristics of a slot jet impinging on a confined concave target surface at constant jet to target spacing. Design/methodology/approach Numerical simulations are used in this research. Jet to target spacing, H/B is varying from 1.0 to 2.2, B is the slot width. The jet Reynolds number, Rej, varies from 8,000 to 40,000, and the surface curvature, R2/B, varies from 4 to 20. Results of the target surface heat transfer, flow parameters and fluid flow in the concave channel are performed. Findings It is found that an obvious backflow occurs near the upper wall. Both the local and averaged Nusselt numbers considered in the defined region respond positively to the Rej. The surface curvature plays a positive role in increasing the averaged Nusselt number for smaller surface curvature (4-15) but affects little as the surface curvature is large enough (> 15). The thermal performance is larger for smaller surface curvature and changes little as the surface curvature is larger than 15. The jet to target spacing shows a negative effect in heat transfer enhancement and thermal performance. Originality/value The surface curvature effects are conducted by verifying the concave surface with constant jet size. The flow characteristics are first obtained for the confined impingement cases. Then confined and unconfined slot jet impingements are compared. An ineffective point for surface curvature effects on heat transfer and thermal performance is obtained.

scholarly journals Lattice-Boltzmann lattice-spring simulations of two flexible fibers settling in moderate Reynolds number flows

2018 ◽  
Vol 167 ◽  
pp. 341-358
Author(s):  
Ahmed Abdulkareem Alhasan ◽  
Ye Luo ◽  
Tai-Hsien Wu ◽  
Guowei He ◽  
Dewei Qi
Keyword(s):  
Reynolds Number ◽  
Lattice Boltzmann ◽  
Moderate Reynolds Number ◽  
Flexible Fibers ◽  
Reynolds Number Flows ◽  
Boltzmann Lattice

Oscillating Rectilinear Fluid Flow Generator

1968 ◽  
Vol 35 (4) ◽  
pp. 663-668 ◽  
Author(s):  
W. H. Hoppmann ◽  
Edward Kiss
Keyword(s):  
Fluid Flow ◽  
Constitutive Equations ◽  
Stokes Equations ◽  
Fluid Motion ◽  
Flow Characteristics ◽  
Viscosity Coefficient ◽  
Longitudinal Axis ◽  
Navier Stokes ◽  
Flow Generator ◽  
External Tube

A Rectilinear Fluid Flow Generator of an oscillating type has been developed for the purpose of studying the rheological properties and flow characteristics of both Newtonian and non-Newtonian liquids [1]. It consists essentially of two long horizontal concentric cylinders, in which the annulus is filled with a liquid. The external tube is mounted on elastic supports, while the internal tube can be harmonically oscillated axially at a predetermined frequency and amplitude. The motion of the external tube and the resultant force (liquid drag) acting on it are readily measurable at any time. The principle of the apparatus depends on the fact that the outside tube motion is dynamically coupled to the inside tube motion by the liquid in the annulus which itself is caused to move by the controlled oscillations of the inside tube. It is assumed, at least in principle, that if the motion of the outside tube is known for a given motion of the inside tube, the constitutive equations for the liquid can be determined. Or conversely, if the constitutive equations are known, the motion of the outside tube can be calculated for a given motion of the inside driving cylinder. It has been shown that the solution of the Navier-Stokes equations can be obtained for the flow of a viscous liquid within the annulus between two infinitely long concentric tubes, for the case where the fluid motion is generated by a rectilinear harmonic motion of the inner tube while the outer tube is assumed to be supported by elastic springs and moving parallel to its longitudinal axis. The velocity and shear stress in the fluid have been obtained, and asymptotic solution for drag force, and tube motions, as well as a method for determining the liquid viscosity coefficient are discussed. It is shown that the theoretical solution is important for the study of the motions of the Rectilinear Fluid Flow Generator.

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