Radiation of waves by a submerged nearly circular rough plate in ice‐covered ocean

2021 ◽  
Author(s):  
Arijit Das ◽  
Soumen De ◽  
B. N. Mandal
Keyword(s):  
Rough Plate

Friction Factor Behavior From Flat-Plate Tests of 12.15 mm Diameter Hole-Pattern Roughened Surfaces

2011 ◽  
Author(s):  
Thanesh Deva Asirvatham ◽  
Dara W. Childs ◽  
Stephen Phillips
Keyword(s):  
Reynolds Number ◽  
Flat Plate ◽  
Friction Factor ◽  
Dynamic Pressure ◽  
Reynolds Numbers ◽  
Stagnation Temperature ◽  
Flat Plates ◽  
Number Range ◽  
Current Test ◽  
Rough Plate

A flat-plate tester is used to measure the friction-factor behavior for a hole-pattern-roughened surface facing a smooth surface with compressed air as the medium. Measurements of mass flow rate, static pressure drop and stagnation temperature are carried out and used to find a combined (stator + rotor) Fanning friction factor value. In addition, dynamic pressure measurements are made at four axial locations at the bottom of individual holes of the rough plate and at facing locations in the smooth plate. The description of the test rig and instrumentation, and the procedure of testing and calculation are explained in detail in Kheireddin in 2009 and Childs et al. in 2010. Three hole-pattern flat-plates with a hole-pattern diameter of 12.15 mm were tested having depths of 0.9, 1.9, and 2.9 mm. Tests were done with clearances at 0.254, 0.381, and 0.653 mm, and inlet pressures of 56, 70 and 84 bar for a range of pressure ratios, yielding a Reynolds-number range of 100,000 to 800,000. The effects of Reynolds number, clearance, inlet pressure, and hole depth on friction factor are studied. The data are compared to friction factor values of three hole-pattern flat-plates with 3.175 mm diameter holes with hole depths of 1.9, 2.6, and 3.302 mm tested in the same rig described by Kheireddin in 2009. The test program was initiated mainly to investigate a “friction-factor jump” phenomenon cited by Ha et al. in 1992 in test results from a flat-plate tester using facing hole-pattern plates where, at elevated values of Reynolds numbers, the friction factor began to increase steadily with increasing Reynolds numbers. Friction-factor jump was not observed in any of the current test cases.

Lamb wave attenuation in a rough plate. I. Analytical and experimental results in an anisotropic plate

2008 ◽  
Vol 104 (7) ◽  
pp. 074908 ◽  
Author(s):  
Catherine Potel ◽  
Damien Leduc ◽  
Bruno Morvan ◽  
Claude Depollier ◽  
Anne-Christine Hladky-Hennion ◽  
...  
Keyword(s):  
Lamb Wave ◽  
Anisotropic Plate ◽  
Wave Attenuation ◽  
Experimental Results ◽  
Rough Plate

Lamb wave attenuation in a rough plate. II. Analytical and numerical results in a fluid plate

2008 ◽  
Vol 104 (7) ◽  
pp. 074909 ◽  
Author(s):  
Catherine Potel ◽  
Damien Leduc ◽  
Bruno Morvan ◽  
Claude Depollier ◽  
Anne-Christine Hladky-Hennion ◽  
...  
Keyword(s):  
Lamb Wave ◽  
Wave Attenuation ◽  
Numerical Results ◽  
Rough Plate

On the Skin Friction Coefficient for a Fully Rough Flat Plate

1983 ◽  
Vol 105 (3) ◽  
pp. 364-365 ◽  
Author(s):  
A. F. Mills ◽  
Xu Hang
Keyword(s):  
Experimental Data ◽  
Friction Coefficient ◽  
Velocity Profile ◽  
Skin Friction ◽  
Skin Friction Coefficient ◽  
Momentum Equation ◽  
Average Error ◽  
Friction Theory ◽  
Rough Plate ◽  
New Skin

A comparison of the Prandtl-Schlichting formula for skin friction of a fully rough plate with recently obtained experimental data shows an average error of 17.5 percent. It is suggested that the reason for this discrepancy is a failure to account for the wake component of the velocity profile. The integral momentum equation is used to derive a new skin friction theory which when compared to the same data gives an average error of 2.7 percent. A new skin friction formula is proposed which is valid over a wide parameter range.

Heat transport properties of plates with smooth and rough surfaces in turbulent thermal convection

2014 ◽  
Vol 740 ◽  
pp. 28-46 ◽  
Author(s):  
Ping Wei ◽  
Tak-Shing Chan ◽  
Rui Ni ◽  
Xiao-Zheng Zhao ◽  
Ke-Qing Xia
Keyword(s):  
Boundary Layer ◽  
Transport Properties ◽  
Heat Transport ◽  
Thermal Convection ◽  
The Other ◽  
Scaling Exponent ◽  
Present Level ◽  
Experimental Resolution ◽  
Rough Plate ◽  
Heat Transport Properties

AbstractWe present an experimental study of turbulent thermal convection with smooth and rough surface plates in various combinations. A total of five cells were used in the experiments. Both the global $\mathit{Nu}$ and the $\mathit{Nu}$ for each plate (or the associated boundary layer) are measured. The results reveal that the smooth plates are insensitive to the surface (rough or smooth) and boundary conditions (i.e. nominally constant temperature or constant flux) of the other plate of the same cell. The heat transport properties of the rough plates, on the other hand, depend not only on the nature of the plate at the opposite side of the cell, but also on the boundary condition of that plate. It thus appears that, at the present level of experimental resolution, the smooth plate can influence the rough plate, but cannot be influenced by either the rough or the smooth plates. It is further found that the scaling of $\mathit{Nu}$ with $\mathit{Ra}$ for all of the smooth plates is consistent with the classical $1/ 3$ exponent. But the scaling exponent for the global $\mathit{Nu}$ for the cell with both plates being smooth is definitely less than $1/ 3$ (this result itself is consistent with all previous studies at comparable parameter range). The discrepancy between the $\mathit{Nu}$ behaviour at the whole-cell and individual-plate levels is not understood and deserves further investigation.

Heat Transfer Augmentation for Air Jet Impinged on Rough Surface

1997 ◽  
Author(s):  
W. M. Chakroun ◽  
S. F. Al-Fahed ◽  
A. A. Abdel-Rehman
Keyword(s):  
Heat Transfer ◽  
Turbulence Intensity ◽  
Flow Characteristics ◽  
Mean Velocity ◽  
Potential Core ◽  
Transfer Data ◽  
Nusselt Numbers ◽  
Air Jet ◽  
Rough Plate ◽  
The Mean

An experimental investigation of heat transfer from round air jet impinging normally from below on flat square plates was performed. Smooth and rough plates were used to collect heat transfer data as well as velocity and turbulence intensity profiles. The heat transfer data have been collected for Reynolds numbers ranging from 6500 to 19000. The nozzle-to-plate distances ranged from 0.05 to 15 to cover both the potential core of the jet and the far region. The study was made to investigate the effect of roughness on the local and average heat transfer values and on the fluid characteristics. The roughness was composed of cubes of 1mm dimension distributed uniformly along the plate. The local and average Nusselt numbers for the rough plate showed an increase ranging from 8.9% to 28 % over those obtained for the smooth plate. Roughness was seen to have a strong effect on the flow characteristics, it affected the mean velocity as well as the turbulence intensity of the flow. The mean velocity profiles for the smooth case at r/D = 1 and r/D = 2.5 had steeper near-wall velocity gradient compared with the rough case. Roughness caused an increase in the turbulence intensity of the flow.

Velocity measurements close to a rough plate oscillating in its own plane

1976 ◽  
Vol 73 (4) ◽  
pp. 673-691 ◽  
Author(s):  
D. C. Keiller ◽  
J. F. A. Sleath
Keyword(s):  
Kinematic Viscosity ◽  
Maximum Velocity ◽  
Angular Frequency ◽  
Half Cycle ◽  
Sphere Diameter ◽  
Hot Wire ◽  
Velocity Measurements ◽  
Fluid Velocities ◽  
Rough Plate ◽  
Rough Beds

Measurements are described of the fluid velocities close to rough beds oscillating in their own plane. The roughness with which most of the results were obtained consisted of smooth spheres closely packed in hexagonal formation. Some results are also given for beds of gravel. The beds were oscillated with simple harmonic motion in still air and the measurements were made with a hot-wire anemometer.The measurements very close to the beds of smooth spheres show two maxima in the velocity profile during each half-cycle. One maximum corresponds to a component of velocity which varies nearly sinusoidally with time. The second forms quite a sharp peak and occurs close to ωt= 90°, 270°, where ω is the angular frequency of oscillation andtis time measured from the instant of maximum velocity of the plate. The phase at which this peak occurs shows little variation with distance from the bed. For values of βD> 3·0, where β = (ω/2ν)½, ν is the kinematic viscosity andDis the sphere diameter, the maximum velocity during each half-cycle is found at this peak over at least a certain range of distances from the bed. The variation with height of the nearly sinusoidal component of velocity is quite close to that given by Stokes’ (1851) solution for a flat plate. The peak at ωt= 90°, 270°, however, rises from zero at the bed to a maximum at a distance of about one-eighth of a sphere diameter above the crests and then falls off again.The measurements with beds of gravel show a variation in velocity similar to that observed by Kalkanis (1957, 1964) and Sleath (1970). Because of the irregularity of the surface it is difficult to draw definite conclusions about the flow in the immediate vicinity of the bed.A number of tests were carried out, with the beds of spheres, using a wire slanted at 45° to the bed in order to determine the velocity productuw.

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