A Finite-Element Study of Newtonian and Power-Law Fluids in Conical Channel Flow

1997 ◽  
Vol 119 (2) ◽  
pp. 341-346 ◽  
Author(s):  
S. H. Garrioch ◽  
D. F. James
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Conical Flow ◽  
Shear Thinning Fluids ◽  
Conical Channel ◽  
Power Law Fluids ◽  
Converging Flow ◽  
Flow Through ◽  
Converging Flow Rheometer

A numerical study of Newtonian and shear-thinning fluids in high-speed, laminar flow through a conical channel is presented. Using a variety of cone-angles and Reynolds numbers on the order of 100, converging flow is mapped according to several characteristics: the angle at which separation occurs at the cone outlet, the extent to which sink-flow is approximated, and the pressure drop through the cone. While the data provides a fundamental description of conical flow, it may be of particular usefulness to rheologists in establishing an inelastic baseline for a converging-flow rheometer.

A Coupled Overlapping Domain Method for the Computation of Transitional Flow Through Artificial Heart Valves

2012 ◽  
Author(s):  
A. C. Verkaik ◽  
A. C. B. Bogaerds ◽  
F. Storti ◽  
F. N. van de Vosse
Keyword(s):  
High Speed ◽  
Heart Valves ◽  
Reynolds Numbers ◽  
Transitional Flow ◽  
Small Scale ◽  
High Deformation ◽  
Artificial Heart Valves ◽  
Laminar And Turbulent Flow ◽  
Flow Through ◽  
Dependent Flow

When blood is pumped through the aortic valves, it has a time dependent flow with a relatively high speed, resulting in Reynolds numbers between 1500 and 3000. Hence, flow is in the transitional regime between laminar and turbulent flow. Transitional flow contains small scale fluctuations, see Figure 1, and may result in local high deformation rates.

Numerical study of the air flow through an air-conditioning unit on high-speed trains

2019 ◽  
Vol 187 ◽  
pp. 26-35 ◽  
Author(s):  
Xueliang Li ◽  
Fan Wu ◽  
Yu Tao ◽  
Mingzhi Yang ◽  
Robert Newman ◽  
...  
Keyword(s):  
Air Conditioning ◽  
High Speed ◽  
Numerical Study ◽  
Air Flow ◽  
High Speed Trains ◽  
Flow Through

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.

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.

Two Dimensional Unsteady Laminar Flow of Power Law Fluids Past a Square Cylinder: A Numerical Study

2008 ◽  
Author(s):  
Akhilesh K. Sahu ◽  
Raj P. Chhabra ◽  
V. Eswaran
Keyword(s):  
Reynolds Number ◽  
Power Law ◽  
Shear Thickening ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Shear Thinning ◽  
Shear Thinning Fluids ◽  
Power Law Fluids ◽  
Shear Thickening Fluids ◽  
Edge Separation

The two-dimensional and unsteady flow of power-law fluids past a long square cylinder has been investigated numerically in the range of conditions 60 ≤ Re ≤ 160 and 0.5 ≤ n ≤ 2.0. Over this range of Reynolds numbers, the flow is periodic in time for Newtonian fluids. However, no such information is available for power law fluids. A semi-explicit finite volume method has been used on a non-uniform collocated grid arrangement to solve the governing equations. The macroscopic quantities such as drag coefficients, Strouhal number, lift coefficient as well as the detailed kinematic variables like stream function, vorticity and so on, have been calculated as functions of the pertinent dimension-less groups. In particular, the effects of Reynolds number and of the power-law index have been investigated in the unsteady laminar flow regime. The leading edge separation in shear-thinning fluids produces an increase in drag values with the increasing Reynolds number, while shear-thickening behaviour delays the leading edge separation. So, the drag coefficient in the above-mentioned range of Reynolds number, Re, in shear-thinning fluids (n < 1) initially decreases but at high values of the Reynolds number, it increases. As expected, on the other hand, in case of shear-thickening fluids (n > 1) drag coefficient reduces with Reynolds number, Re. Furthermore, the present results also suggest the transition from steady to unsteady flow conditions to occur at lower Reynolds numbers in shear-thickening fluids than that in Newtonian fluids. Also, the spectra of lift signal for shear-thickening fluids show that the flow is truly periodic in nature with a single dominant frequency in the above range of Reynolds number. In shear-thinning fluids at higher Re, quasi-periodicity sets in with additional frequencies, which indicate the transition from the 2-D to 3-D flows.

Variation of the Recirculation Length of Newtonian and Non-Newtonian Power-Law Fluids in Laminar Flow Through a Suddenly Expanded Axisymmetric Geometry

2006 ◽  
Vol 129 (2) ◽  
pp. 245-250 ◽  
Author(s):  
Debabrata Nag ◽  
Amitava Datta
Keyword(s):  
Laminar Flow ◽  
Power Law ◽  
Numerical Study ◽  
Shear Thickening ◽  
Expansion Ratio ◽  
Rheological Parameters ◽  
Power Law Fluids ◽  
Wide Range ◽  
Flow Through ◽  
Recirculation Length

A numerical study has been carried out for the laminar flow of Newtonian and non-Newtonian power-law fluids through a suddenly expanded axisymmetric geometry. Mathematical correlations are proposed for the prediction of the length of the recirculating eddy in terms of Reynolds number, expansion ratio and rheological parameters. A wide range of expansion ratios (1.25⩽ER⩽8.0) has been covered for the Newtonian fluid and both the shear-thinning and shear-thickening flow characteristic fluids have been considered for the non-Newtonian fluids.

scholarly journals Numerical Study for Optimizing Heat Transfer in High Speed Rotating Components

1998 ◽  
Vol 4 (3) ◽  
pp. 151-161 ◽  
Author(s):  
S. Wittig ◽  
S. Kim ◽  
Th. Scherer ◽  
I. Weissert
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
High Speed ◽  
Numerical Study ◽  
Rotating Disks ◽  
Rotating System ◽  
Local Flow ◽  
Flow Through ◽  
Air Flows ◽  
Cooling Air

Cooling of high speed rotating components is a typical situation found in turbomachinery as well as in automobile engines. Accurate knowledge of discharge coefficients and heat transfer of related components is essential for the high performance of the whole engine. This can be achieved by minimized cooling air flows and avoidance of hot spots. In high speed rotating clutches for example aerodynamic investigations improving heat transfer have not been considered in the past. Advanced concepts of modern plate design try to reduce thermal loads by convective cooling methods. Therefore, secondary cooling air flows have to be enhanced by an appropriate design of the rotor stator system with orifices. CFD modelling is used to improve the basic understanding of the flow field in typical geometries used in these systems.The computational results are obtained by a 3-D-finite-volume-code based on body fitted structured grids. The Navier Stokes equations are solved by a pressure-correction method combined with the standard k-e-turbulence model. Considering the rotation of orifices in disks or shafts, the frame of reference has to be changed to the rotating system. The flow through orifices in high speed rotating disks can be calculated with a high level of accuracy in comparison with experiments as shown in Wittig et al. [1994].Numerical results of the flow in a high speed rotating system are presented with emphasis on geometrical variations. Calculations are carried out in order to find an optimum design in terms of position and size of the orifices in the housing. These variations induce different physical phenomena. Special consideration is directed towards the basic problems of the flow through orifices in high speed rotating disks and shafts and the flow inside rotor-stator systems. As expected, the very complex flow fields are dominated by rotational effects. In addition it is shown that differences occur between the configuration of optimized mass flow rate and the geometry with a maximum of total heat transfer. Obviously, optimization procedures are dependent on the knowledge of the local flow field and cannot be performed without advanced CFD-methods. It is demonstrated that the approach presented here is suitable for these tasks.

An Experimental and Numerical Study of Heat Transfer and Pressure Loss in a Rectangular Channel With V-Shaped Ribs

2006 ◽  
Author(s):  
Michael Maurer ◽  
Jens von Wolfersdorf ◽  
Michael Gritsch
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Pressure Loss ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Transfer Enhancement ◽  
High Reynolds Numbers ◽  
High Reynolds

An experimental and numerical study was conducted to determine the thermal performance of V-shaped ribs in a rectangular channel with an aspect ratio of 2:1. Local heat transfer coefficients were measured using the steady state thermochromic liquid crystal technique. Periodic pressure losses were obtained with pressure taps along the smooth channel sidewall. Reynolds numbers from 95,000 to 500,000 were investigated with V-shaped ribs located on one side or on both sides of the test channel. The rib height-to-hydraulic diameter ratios (e/Dh) were 0.0625 and 0.02, and the rib pitch-to-height ratio (P/e) was 10. In addition, all test cases were investigated numerically. The commercial software FLUENT™ was used with a two-layer k-ε turbulence model. Numerically and experimentally obtained data were compared. It was determined that the heat transfer enhancement based on the heat transfer of a smooth wall levels off for Reynolds numbers over 200,000. The introduction of a second ribbed sidewall slightly increased the heat transfer enhancement whereas the pressure penalty was approximately doubled. Diminishing the rib height at high Reynolds numbers had the disadvantage of a slightly decreased heat transfer enhancement, but benefits in a significantly reduced pressure loss. At high Reynolds numbers small-scale ribs in a one-sided ribbed channel were shown to have the best thermal performance.

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