Fluid Drag on a Sphere Rolling in a Tube

1967 ◽  
Vol 34 (3) ◽  
pp. 538-540
Author(s):  
A. B. Bauer ◽  
R. A. DuPuis
Keyword(s):  
Incompressible Fluid ◽  
Drag Force ◽  
Reynolds Numbers ◽  
Vertical Tube ◽  
Experimental Results ◽  
Constant Speed ◽  
Sphere Diameter ◽  
Fluid Drag ◽  
Drag Law ◽  
Good Agreement

The incompressible fluid drag force on a sphere rolling at constant speed in a closed-end tube has been analyzed for the case where the tube inside diameter is only slightly larger than the sphere diameter. One drag law is found for Reynolds numbers much less than 75π/4λ1/2, where λ is a parameter defined by the sphere and tube diameters. A second drag law is found for Reynolds numbers much larger than 75π/4λ1/2. Experimental results show good agreement with these drag laws. The first law is almost identical with the results of Christopherson and Dowson, and of McNown, et al., for a sphere falling in a vertical tube.

Simulation of Sphere’s Motion Induced by Shock Waves

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Dan Igra ◽  
Ozer Igra ◽  
Lazhar Houas ◽  
Georges Jourdan
Keyword(s):  
Shock Waves ◽  
Drag Coefficient ◽  
Drag Force ◽  
Stationary Flow ◽  
Experimental Results ◽  
Experimental Findings ◽  
Sphere Drag ◽  
Simulation Scheme ◽  
Good Agreement

Simulations of experimental results appearing in Jourdan et al. (2007, “Drag Coefficient of a Sphere in a Non-Stationary Flow: New Results,”Proc. R. Soc. London, Ser. A, 463, pp. 3323–3345) regarding acceleration of a sphere by the postshock flow were conducted in order to find the contribution of the various parameters affecting the sphere drag force. Based on the good agreement found between present simulations and experimental findings, it is concluded that the proposed simulation scheme could safely be used for evaluating the sphere’s motion in the postshock flow.

Forced Convection in a Porous Channel With Discrete Heat Sources

2000 ◽  
Vol 123 (2) ◽  
pp. 404-407 ◽  
Author(s):  
C. Cui ◽  
X. Y. Huang ◽  
C. Y. Liu
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Porous Channel ◽  
Heat Sources ◽  
Nusselt Numbers ◽  
Discrete Heat Sources ◽  
Flow Through ◽  
Good Agreement

An experimental study was conducted on the heat transfer characteristics of flow through a porous channel with discrete heat sources on the upper wall. The temperatures along the heated channel wall were measured with different heat fluxes and the local Nusselt numbers were calculated at the different Reynolds numbers. The temperature distribution of the fluid inside the channel was also measured at several points. The experimental results were compared with that predicted by an analytical model using the Green’s integral over the discrete sources, and a good agreement between the two was obtained. The experimental results confirmed that the heat transfer would be more significant at leading edges of the strip heaters and at higher Reynolds numbers.

Correlation Between Contact Start/Stop and Constant Speed Drag Testing in Magnetic Head-Disk Tribology

1993 ◽  
Vol 115 (3) ◽  
pp. 387-391 ◽  
Author(s):  
S. K. Ganapathi ◽  
F. E. Talke
Keyword(s):  
Experimental Data ◽  
Contact Force ◽  
Experimental Results ◽  
Constant Speed ◽  
Optical Profilometry ◽  
Magnetic Head ◽  
Good Agreement

A model to establish the correlation between wear in constant speed drag testing and contact start/stop testing is developed. The model is based on the Archard wear equation and uses the quasi-steady Kita-Kogure-Mitsuya model for the transition of a slider from sliding to flying to calculate the velocity dependent contact force between the slider and disk during start/stop. Experimental results for the wear of a zirconia overcoated disk are obtained for both start/stop and constant speed drag testing as a function of the number of repeated cycles using optical profilometry. The correlation between predictions and experimental data shows good agreement for up to at least 10,000 cycles of sliding.

A Theory of Sharp-Edged Orifices

1937 ◽  
Vol 4 (2) ◽  
pp. A53-A54
Author(s):  
W. E. Howland
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Discharge Coefficient ◽  
Reynolds Numbers ◽  
Experimental Results ◽  
Low Reynolds Numbers ◽  
Circular Orifice ◽  
Coefficient Of Discharge ◽  
Theoretical Considerations ◽  
Good Agreement

Abstract The author presents a figure in which the coefficient of discharge Cd, velocity Cv, and contraction Cc determined by several investigators are plotted logarithmically as points against Reynolds’ numbers. Curves for the coefficients drawn by the author, based on theoretical considerations, show good agreement with the experimental data, thus throwing some light upon the basic phenomena of the discharge of sharp-edged orifices. The variation of the coefficient of discharge of a circular orifice as a function of the Reynolds number is explained as a purely viscous phenomenon for low Reynolds numbers, and by means of a momentum analysis for higher speeds. The analysis presented by the author leads to the development of several formulas for the discharge coefficient, which formulas are in fair agreement with experimental results.

An Experimental and Theoretical Study of Heat Transfer in Vertical Tube Flows

1978 ◽  
Vol 100 (1) ◽  
pp. 86-91 ◽  
Author(s):  
R. Greif
Keyword(s):  
Heat Transfer ◽  
Turbulent Flows ◽  
Theoretical Study ◽  
Numerical Solutions ◽  
Reynolds Numbers ◽  
Vertical Tube ◽  
Laminar Flows ◽  
Radial Temperature ◽  
Rayleigh Numbers ◽  
Good Agreement

An experimental and theoretical study was carried out for the heat transfer in laminar and turbulent tube flows with air and argon. Radial temperature profiles were measured at a location 108 tube diameters from the inlet of the vertical, electrically heated test section. The temperature of the tube wall was also measured. The experimental data were in good agreement with the results obtained from numerical solutions of the conservation equations and from simplified, fully developed solutions. For turbulent flows the Reynolds numbers varied from 10,000 to 19,500; for laminar flows the Reynolds numbers varied from 1850 to 2100 while the Rayleigh numbers varied from 70 to 80.

The Resistance to Rotation of Free and Enclosed Disks

1971 ◽  
Vol 38 (4) ◽  
pp. 749-755 ◽  
Author(s):  
T. Miloh ◽  
M. Poreh
Keyword(s):  
Polymer Solutions ◽  
Theoretical Calculations ◽  
Reynolds Numbers ◽  
General Analysis ◽  
Experimental Results ◽  
High Reynolds Numbers ◽  
Dilute Polymer Solutions ◽  
High Reynolds ◽  
Good Agreement

A general analysis of the resistance to rotation of disks at high Reynolds numbers is presented. The theoretical calculations of the fluid-induced torque on free and enclosed, smooth and rough disks, as well as torque induced by the dilute polymer solutions, are found to be in good agreement with experimental results.

Experimental Determination of Friction Factors for Straight and Curved Microchannels

2010 ◽  
Vol 5 (3) ◽  
pp. 63-70
Author(s):  
Vladimir М. Aniskin ◽  
Kseniya V. Adamenko ◽  
Anatoliy A. Maslov
Keyword(s):  
Friction Factor ◽  
Software Package ◽  
Reference Value ◽  
Reynolds Numbers ◽  
Experimental Results ◽  
Friction Factors ◽  
Inner Diameter ◽  
Curved Section ◽  
Good Agreement

This article presents experimental results of determining the friction factors for two microchannels with circular crosssection: rectilinear and curvilinear. The inner diameter of channels in both cases was 100 microns. The Reynolds numbers ranged from 110 to 2216. Pressure measurement was carried out simultaneously in four locations along the channel. Friction factor for the straight microchannel was in good agreement with the theoretical value for the round smooth tubes. For the curved microchannel, the value of friction factor of the curved section was 17 percent less than the reference value for smoothly curved tubes. The experimental results are compared with calculations which were made using the software package Fluent

scholarly journals LES of spray in crossflow – Effect of droplet distortion

2016 ◽  
Vol 9 (1) ◽  
pp. 55-70 ◽  
Author(s):  
Anubhav Sinha ◽  
RV Ravikrishna
Keyword(s):  
Initial Conditions ◽  
Spherical Shape ◽  
Experimental Results ◽  
Mass System ◽  
Large Eddy ◽  
Droplet Sizes ◽  
Experimental Values ◽  
Early Breakup ◽  
Drag Law ◽  
Good Agreement

The present investigation is focused on modeling of spray in crossflow using Large Eddy Simulations (LES). The modeling efforts are supported by experiments which are used both to provide accurate boundary and initial conditions and to evaluate droplet shapes in the near nozzle region. The droplets are modeled as Lagrangian parcels in an Eulerian continuum. Droplets in such configuration have been found to be distorted and not in perfect spherical shape from experimental results of our previous study. Droplet distortion is computed by Taylor-Analogy Breakup (TAB) distortion model. Each droplet is modelled as damped spring-mass system, where surface tension acts as a spring on the mass of the droplet and viscous dissipation provides the damping effect. The effort is to examine the effect of drag law used and the effect of this distortion on the droplet sizes produced in the flow field. Spray wind-ward trajectory and droplet sizes obtained from simulations are compared with the experimental results available. Although computational spray trajectory shows a reasonable match with experimental values, droplet sizes using the standard TAB model are found to be larger than that from experimental observation. To account for this distortion and its role in early breakup of droplets, constants of the TAB model are modified and the droplet sizes are found to be in good agreement with the experimental data.

An Investigation of the Corner Secondary Flows Generated in Planar Nozzles

1974 ◽  
Vol 96 (3) ◽  
pp. 234-245
Author(s):  
W. B. Wagner ◽  
J. A. Owczarek
Keyword(s):  
Boundary Layer ◽  
Total Pressure ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Flow Speed ◽  
Secondary Flows ◽  
Experimental Results ◽  
Average Flow ◽  
Aspect Ratios ◽  
Good Agreement

An experimental study was made of the total pressure distribution in the corner secondary flow generated in two planar nozzles having different contours. Also, an analysis was made of the extent of the sidewall boundary layer migration caused by the cross flow and of its accumulation in the corner between the sidewall and horizontal nozzle walls at exits of planar nozzles. A comparison of the calculated and experimental results was made. Reasonably good agreement was found between the analytical and experimental results. The Reynolds numbers considered in this study, based on the average flow speed at nozzle exits and on the nozzle widths, were 5000, 10,000, and 20,000. The nozzle aspect ratios were 4 and 2.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

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