Friction Factor for Flow in Rectangular Ducts With One Side Rib-Roughened

1994 ◽  
Vol 116 (3) ◽  
pp. 488-493 ◽  
Author(s):  
B. Youn ◽  
C. Yuen ◽  
A. F. Mills
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Software Package ◽  
Diameter Ratio ◽  
Numerical Results ◽  
Wall Function ◽  
Height Ratio ◽  
Aspect Ratios ◽  
Flow Through ◽  
Rib Roughened

Numerical simulations of incompressible turbulent flow through rectangular ducts with one side rib-roughened were performed to determine pressure drop. The “PHOENICS” software package was used for the computations, which required provision of a wall function for transverse rib-roughened surfaces. The present study was conducted in the range of 105≤ Reynolds number ≤ 107, 0.01 ≤ rib height to hydraulic diameter ratio ≤ 0.04, 10≤ pitch to rib height ratio ≤ 40. Using the numerical results, friction factor charts for various aspect ratios were generated. The numerical results agreed well with experimental data that was obtained for 105 < Reynolds number < 2 × 105. In addition, a scheme for predicting friction factor using existing correlations for smooth and rough walls was developed.

Effect of Surface Roughness on Gaseous Flow Through Microchannels

2000 ◽  
Author(s):  
Stephen E. Turner ◽  
Hongwei Sun ◽  
Mohammad Faghri ◽  
Otto J. Gregory
Keyword(s):  
Surface Roughness ◽  
Reynolds Number ◽  
Friction Factor ◽  
Reynolds Numbers ◽  
Helium Flow ◽  
Local Pressure ◽  
Aspect Ratios ◽  
Corrugated Surfaces ◽  
Flow Through ◽  
Effect Of Surface

Abstract This paper presents an experimental investigation on nitrogen and helium flow through microchannels etched in silicon with hydraulic diameters between 10 and 40 microns, and Reynolds numbers ranging from 0.3 to 600. The objectives of this research are (1) to fabricate microchannels with uniform surface roughness and local pressure measurement; (2) to determine the friction factor within the locally fully developed region of the microchannel; and (3) to evaluate the effect of surface roughness on momentum transfer by comparison with smooth microchannels. The friction factor results are presented as the product of friction factor and Reynolds number plotted against Reynolds number. The following conclusions have been reached in the present investigation: (1) microchannels with uniform corrugated surfaces can be fabricated using standard photolithographic processes; and (2) surface features with low aspect ratios of height to width have little effect on the friction factor for laminar flow in microchannels.

Local Heat Transfer Distribution in a Rotating Serpentine Rib-Roughened Flow Passage

1993 ◽  
Vol 115 (3) ◽  
pp. 560-567 ◽  
Author(s):  
N. Zhang ◽  
J. Chiou ◽  
S. Fann ◽  
W.-J. Yang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Performance ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Performance ◽  
Height Ratio ◽  
Nusselt Numbers ◽  
Rayleigh Numbers ◽  
Rib Roughened

Experiments are performed to determine the local heat transfer performance in a rotating serpentine passage with rib-roughened surfaces. The ribs are placed on the trailing and leading walls in a corresponding posited arrangement with an angle of attack of 90 deg. The rib height-to-hydraulic diameter ratio, e/Dh, is 0.0787 and the rib pitch-to-height ratio, s/e, is 11. The throughflow Reynolds number is varied, typically at 23,000, 47,000, and 70,000 in the passage both at rest and in rotation. In the rotation cases, the rotation number is varied from 0.023 to 0.0594. Results for the rib-roughened serpentine passages are compared with those of smooth ones in the literature. Comparison is also made on results for the rib-roughened passages between the stationary and rotating cases. It is disclosed that a significant enhancement is achieved in the heat transfer in both the stationary and rotating cases resulting from an installation of the ribs. Both the rotation and Rayleigh numbers play important roles in the heat transfer performance on both the trailing and leading walls. Although the Reynolds number strongly influences the Nusselt numbers in the rib-roughened passage of both the stationary and rotating cases, Nuo and Nu, respectively, it has little effect on their ratio Nu/Nuo.

Analytical Solution for Newtonian Laminar Flow Through the Concave and Convex Ducts

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
M. Firouzi ◽  
S. H. Hashemabadi
Keyword(s):  
Reynolds Number ◽  
Steady State ◽  
Friction Factor ◽  
Cross Section ◽  
Cross Sections ◽  
Fully Developed Flow ◽  
Pipe Flows ◽  
Dimensionless Velocity ◽  
Flow Through ◽  
Fanning Friction Factor

In this paper, the motion equation for steady state, laminar, fully developed flow of Newtonian fluid through the concave and convex ducts has been solved both numerically and analytically. These cross sections can be formed due to the sedimentation of heavy components such as sand, wax, debris, and corrosion products in pipe flows. The influence of duct cross section on dimensionless velocity profile, dimensionless pressure drop, and friction factor has been reported. Finally based on the analytical solutions three new correlations have been proposed for the product of Reynolds number and Fanning friction factor (Cf Re) for these geometries.

Frictional Pressure Drop in Micro-Channel

2004 ◽  
Author(s):  
Yasuo Koizumi ◽  
Hiroyasu Ohtake ◽  
Hiroki Takahashi ◽  
Yoshiaki Ohno
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Friction Factor ◽  
Frictional Pressure Drop ◽  
Turbulent Transition ◽  
Friction Factors ◽  
Turbulent Flow Regime ◽  
Form Pressure ◽  
Laminar And Turbulent Flow ◽  
Flow Through

The friction characteristics of water in a sub-millimeter scale channel were investigated experimentally. The friction factors and the critical Reynolds number were measured using water flow through circular tubes with diameters of 0.5, 0.25 and 0.17 mm. The experimental results show that the measured friction factor for water agreed well with the conventional Poiseuille (λ = 64/Re) and Blasius (λ = 0.316 Re−0.25) equations in laminar and turbulent flow regime; the laminar-turbulent transition Reynolds number was approximately 2300 for diameter 0.5 mm. For diameter 0.25 mm, the friction factor evaluated by the form pressure drop also agreed well with the Poiseuille equation. For diameter 0.17 mm, the measured total friction factor was close to the Poiseuille prediction.

Local Pressure Measurement of Gaseous Flow Through Microchannels

1999 ◽  
Author(s):  
Stephen E. Turner ◽  
Hongwei Sun ◽  
Mohammad Faghri ◽  
Otto J. Gregory
Keyword(s):  
Reynolds Number ◽  
Pressure Distribution ◽  
Friction Factor ◽  
Knudsen Number ◽  
Flow Region ◽  
Reynolds Numbers ◽  
Helium Flow ◽  
Local Pressure ◽  
Pressure Losses ◽  
Flow Through

Abstract This paper presents an experimental investigation on nitrogen and helium flow in microchannels etched in silicon with hydraulic diameters of 9.7, 19.6, and 46.6 μm, and Reynolds numbers ranging from 0. 2 to 1000. The objectives of this research are (1) to measure the pressure distribution along the length of a microchannel; and (2) to determine the friction factor within the fully developed region of the microchannel. The pressure distribution is presented as absolute local pressure plotted against the distance from the microchannel inlet. The friction factor results are presented as the product of friction factor and Reynolds number plotted against Reynolds number with the outlet Knudsen number, Kn, as a curve parameter. The following conclusions have been reached in the present investigation: (1) Pressure losses at the microchannel entrance can be significant; (2) the product, f*Re, when measured sufficiently far away from the entrance and exit is a constant in the laminar flow region; and (3) the friction factor decreases as the Knudsen number increases.

Heat Transfer Augmentation Using an Innovative Helicoidal Finned Absorber Plate in a Solar Air Heater—A Numerical Study

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Shantanu Purohit ◽  
N. Madhwesh ◽  
K. Vasudeva Karanth ◽  
N. Yagnesh Sharma
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Friction Factor ◽  
Diameter Ratio ◽  
Wire Diameter ◽  
Solar Air Heater ◽  
Absorber Plate ◽  
Air Heater ◽  
Pitch Ratio

This study presents an innovative idea to augment heat transfer to an air heater using helicoidal finned arrangement. A parametric analysis of the helicoidal shaped fin geometry is considered with helicoidal pitch ratio of 0.1666–0.3, fin diameter ratio of 1.75–2. For the placement of the fin beneath the absorber plate, longitudinal pitch ratio ranging from 0.0416 to 0.1666 are used. The flow Reynolds number used for the study ranges from 4800 to 25,000. The effects of helicoidal pitch ratio, wire diameter ratio and longitudinal pitch ratio on Nusselt number and friction factor have been discussed. It is seen from the analysis that there is a significant improvement in Nusselt number for the case of helicoidal fin of wire diameter ratio of 1 when compared to base model as well as straight fin model for the operating range of Reynolds number. It is also observed from the analysis that for the helicoidal fin configuration of helicoidal pitch ratio of 0.2333, friction factor appears to be moderate. Flow and roughness parameters for roughened solar air heater have been optimized using thermal-hydraulic enhancement factor (THEF). The study reveals that by the use of helicoidal fins, maximum enhancement in the Nusselt number is found to be 2.21 times when compared to the base model for longitudinal pitch ratio of 0.0416, helicoidal pitch ratio of 0.166 for a fixed wire diameter. The improvement obtained in performance corresponding to increased Nusselt number establishes the efficacy the helicoidal fin design for the absorber plate.

A Series Pressure Drop Representation for Flow Through Orifice Tubes

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
T. A. Jankowski ◽  
E. N. Schmierer ◽  
F. C. Prenger ◽  
S. P. Ashworth
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Simple Model ◽  
Pressure Drop ◽  
Diameter Ratio ◽  
Pressure Drops ◽  
In Series ◽  
Orifice Flow ◽  
Flow Through ◽  
Length To Diameter Ratio

A simple model is developed here to predict the pressure drop and discharge coefficient for incompressible flow through orifices with length-to-diameter ratio greater than zero (orifice tubes) over wide ranges of Reynolds number. The pressure drop for flow through orifice tubes is represented as two pressure drops in series; namely, a pressure drop for flow through a sharp-edged orifice in series with a pressure drop for developing flow in a straight length of tube. Both of these pressure drop terms are represented in the model using generally accepted correlations and experimental data for developing flows and sharp-edged orifice flow. We show agreement between this simple model and our numerical analysis of laminar orifice flow with length-to-diameter ratio up to 15 and for Reynolds number up to 150. Agreement is also shown between the series pressure drop representation and experimental data over wider ranges of Reynolds number. Not only is the present work useful as a design correlation for equipment relying on flow through orifice tubes but it helps to explain some of the difficulties that previous authors have encountered when comparing experimental observation and available theories.

Friction Factor for Isothermal and Nonisothermal Flow Through Porous Media

1977 ◽  
Vol 99 (3) ◽  
pp. 367-373 ◽  
Author(s):  
J. C. Koh ◽  
J. L. Dutton ◽  
B. A. Benson ◽  
A. Fortini
Keyword(s):  
Reynolds Number ◽  
Porous Media ◽  
Friction Factor ◽  
Nonisothermal Flow ◽  
Flow Through Porous Media ◽  
Gaseous Flow ◽  
Pressure Drops ◽  
Flow Through ◽  
Temperature Levels ◽  
Nonisothermal Conditions

Measurements were performed to determine the pressure drops for gaseous flow through porous materials of different microstructures, porosities, and thickness under isothermal and nonisothermal conditions at various temperature levels. Results were satisfactorily correlated by a simple equation relating the friction factor to the Reynolds number and porosities.

scholarly journals The elements of fluid mechanics of bile flow through biliary drainage catheters

2019 ◽  
Vol 12 (1) ◽  
pp. 29-41
Author(s):  
Wenguang Li
Keyword(s):  
Reynolds Number ◽  
Obstructive Jaundice ◽  
Fluid Mechanics ◽  
Pressure Gradient ◽  
Friction Factor ◽  
Flow Rate ◽  
Bile Flow ◽  
Bile Flow Rate ◽  
Flow Through ◽  
Inner Diameter

Obstructive jaundice in the biliary tract can infect blood and result in mortality with a high rate. Percutaneous transhepatic biliary drainage (PTBD) with catheters is a useful solution discharging the obstructive jaundice. However, the elements of fluid mechanics showing clinical performance of a PTBD catheter have been documented little so far. In the article, empirical relationships between bile flow rate and pressure gradient in PTBD catheters were studied in terms of equivalent friction factor for the first time. Firstly, an equivalent friction factor in a catheter was raised and determined based on existing in vitro experimental data of bile flow through the catheters with different materials, various inner diameters and lengths under various pressure differences. Then, an empirical correlation of bile flow rate through a catheter was established based on pressure gradient, inner diameter and bile viscosity. The correlation was used to identify effects of catheter inner diameter and bile viscosity on the bile flow rate under the physiological bile pressure difference across obstructed common bile ducts. The feature of minor hydraulic losses in the catheters was clarified, too. The proposed equivalent friction factor was proportional to Reynolds number in a power of -0.654 in comparison with a power of -1 for the fully developed laminar flow in circular pipes. The bile flow rate through a catheter was proportional to inner diameter, kinematic viscosity, and pressure gradient in the powers of 3.2, -0.5 and 0.74, respectively. The minor hydraulic losses could be significant when Reynolds number was greater than 100.

Sign in / Sign up

Export Citation Format

Share Document