Effect of a Rotational Wake on the Wavemaking Resistance of an Ogive

1970 ◽  
Vol 14 (02) ◽  
pp. 84-99
Author(s):  
J.-C. Tatinclaux
Keyword(s):  
Asymptotic Form ◽  
Surface Profile ◽  
Local Effect ◽  
Wave Resistance ◽  
Wave Profile ◽  
Volume Distribution ◽  
Wake Effect ◽  
Wave Elevation ◽  
Unbounded Fluid

The rotational wake of a two-dimensional ogive in an unbounded fluid is simulated by a volume distribution of vertical line vortices. Expressions for the wave elevation and the wave resistance, including wake effect, are derived. It is found that, with the chosen vorticity, the wave resistance is from 10 percent larger to 35 percent smaller, depending upon the Froude number, than in the irrotational case. It is shown that, when the wave elevation ζ is expressed as the sum of its asymptotic form ζas and a quantity Z(ω;x,y) representing the local effect of the vorticity present in the vicinity of the transverse cut, Eggers' method for the determination of the wave resistance from surface-profile measurements is valid when applied to the asymptotic wave profile, i.e. to the quantity [ζ(x,y) – Z(ω;x,y)].

An Experimental Determination of Pressure Forces on a Ship Model From an Analysis of the Wave Profile

1965 ◽  
Vol 9 (03) ◽  
pp. 113-117
Author(s):  
Grant Lewison
Keyword(s):  
Pressure Distribution ◽  
Experimental Determination ◽  
Wave Resistance ◽  
Wave Profile ◽  
Full Scale ◽  
Axisymmetric Model ◽  
Ship Model ◽  
New Form

A method for the analysis of the wave profile alongside a ship model is presented in a new form. The pressure distribution over an axisymmetric model is computed, and wave resistance and vertical forces are derived from it. The application of the method to other model forms and also to full-scale ships is discussed.

Further Development of a Procedure for Determination of Wave Resistance from Longitudinal-Cut Surface-Profile Measurements

1975 ◽  
Vol 19 (02) ◽  
pp. 65-75
Author(s):  
C.-E. Tsai ◽  
L. Landweber
Keyword(s):  
Linear Equations ◽  
Amplitude Spectrum ◽  
Surface Profile ◽  
Lateral Position ◽  
Wave Resistance ◽  
Source Distribution ◽  
Cut Method ◽  
Block Models ◽  
Further Development

The single-longitudinal-cut method of Moran and Landweber is refined both in the experimental techniques and the analytical procedures. Analytically, a method combining iteration and elimination is used, instead of matrix inversion, to solve the linear equations for the amplitude spectrum; the upper truncation point XT is held constant in the analysis of wave data; and the modified procedures are applied both to the symmetrical source distribution used by Moran as well as to an asymmetrical one. Similar results were obtained with the latter distribution. Experimentally, it was found that the results obtained with the single-longitudinal-cut procedure were sensitive to the lateral position of the cut. Consequently, a multiple-longitudinal-cut technique was developed, using three probes in parallel, with the data analyzed by the method of least squares. Applying the multiple-longitudinal-cut method to a family of four Series 60 models, consistent results among the 0.60-block models were obtained. Furthermore, the wave resistance was found to be essentially constant with respect to wave-record length for the 0.60-block geosims.

Mean-Flow Measurements in the Boundary Layer and Wake and Wave Field of a Series 60 CB = 0.6 Ship Model—Part 2: Scale Effects on Near-Field Wave Patterns and Comparisons with Inviscid Theory

1993 ◽  
Vol 37 (01) ◽  
pp. 16-24
Author(s):  
J. Longo ◽  
F. Stern ◽  
Y. Toda
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Scale Effects ◽  
Near Field ◽  
Wave Profile ◽  
Wave System ◽  
Mean Flow ◽  
Wave Elevation ◽  
Wave Patterns ◽  
Field Wave

Part 2 of this two-part paper presents additional results from a towing-tank experiment conducted in order to explicate the influence of wavemaking by a surface-piercing body on its boundary-layer and wake and provide detailed documentation of the complete flow field appropriate for validating computational methods. In Part 1 (Journal of Ship Research, Dec. 1992), wave profile, local and global wave-elevation, and mean-velocity and pressure field measurements for Froude numbers 0.16 and 0.316 for a 3.048 m Series 60 CB = 0.6 hull form are presented and discussed to point out the essential differences between the flows at low and high Froude number and to assess the nature of the interaction between wavemaking and the boundary layer and wake. In Part 2, scale effects on the near-field wave patterns are examined through wave profile and local and global wave-elevation measurements for 1.829 and 3.048 m models and Froude numbers 0.316, 0.3, and 0.25. The bow-wave amplitude and divergence angle are larger and the stern waves smaller for the smaller model. The latter scale effect is well known, but the former one is a new and unexpected result. Also, comparisons are made between the experimental results and those from a wavy inviscid-flow method, which provides an evaluation of the capabilities of the computational method. Although the computations predict the gross features of the wave system and velocity and pressure fields, they do not simulate the complex details of either the wave system or the flow field, especially close to the hull and wake centerplane.

Determination of the inner-surface profile of a capsule using chromatic confocal spectroscopy

2020 ◽  
Vol 13 (2) ◽  
pp. 266-272
Author(s):  
唐 兴 TANG Xing ◽  
王 琦 WANG Qi ◽  
马小军 MA Xiao-jun ◽  
高党忠 GAO Dang-zhong ◽  
王宗伟 WANG Zong-wei ◽  
...  
Keyword(s):  
Surface Profile ◽  
Inner Surface ◽  
Confocal Spectroscopy

scholarly journals High-resolution fiber-coupled interferometric point sensor for micro- and nano-metrology

2015 ◽  
Vol 82 (7-8) ◽  
Author(s):  
Markus Schake ◽  
Markus Schulz ◽  
Peter Lehmann
Keyword(s):  
High Resolution ◽  
Measurement Errors ◽  
Surface Profile ◽  
Optical Measurements ◽  
High Demand ◽  
Force Microscopy ◽  
Atomic Force ◽  
Measurement Object ◽  
Contact Free

AbstractThe determination of surface roughness is a common challenge in industrial quality assurance. Because tactile techniques like the stylus method or atomic force microscopy run the risk of damaging the measurement object there is a high demand for contact-free optical measurements. In this contribution we demonstrate the feasibility of a high resolution fiber-coupled interferometric point sensor with periodical path length modulation to determine the surface profile of rough surfaces. Measurements on two specimens characterized by different roughness parameters are presented and corrections for common measurement errors, due to phase ambiguity are discussed.

Resonant oscillations of water waves I. Theory

1968 ◽  
Vol 306 (1484) ◽  
pp. 5-22 ◽  
Keyword(s):  
Resonant Frequency ◽  
Water Waves ◽  
Surface Profile ◽  
Sharp Change ◽  
Classical Wave ◽  
Small Parameters ◽  
Linearized Theory ◽  
Classical Wave Equation ◽  
Normal Laboratory

A theory is presented to describe the oscillations of a liquid in a tank near a resonant frequency, where linearized theory is invalid. It is shown that although the oscillations are described adequately by the classical wave equation, the boundary conditions cannot be properly satisfied unless the non-linear terms are included. The effects of dissipation and dispersion are also significant in the determination of the oscillations, even though the terms to which they give rise in the equations are multiplied by small parameters under normal laboratory conditions. When the former is dominant a weak bore is formed which travels to and fro in the tank and is continually reflected at either end. When dispersion is significant the surface profile can be likened to a series of cnoidal waves which also travel along the tank and suffer reflexion. Several novel features appear. The amplitude does not increase monotonically as the nominal resonant frequency is approached. There are several distinct frequencies at which there is a sharp change in amplitude and in the form of the profile. More than one stable oscillation is possible at some frequencies. Near a resonant frequency higher than the fundamental, subharmonic oscillations are possible over part of the range.

scholarly journals Determination of Nonconductive Coating Thickness Using Electrical Contact Conductance and Surface Profile

Coatings ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 310 ◽  
Author(s):  
Kyungmok Kim ◽  
Jaewook Lee
Keyword(s):  
Coating Thickness ◽  
Electrical Contact ◽  
Surface Profile ◽  
Steel Specimen ◽  
Vertical Displacement ◽  
Relative Displacement ◽  
Optical Microscope ◽  
Electrical Contact Resistance ◽  
Contact Conductance

This paper describes a method to determine the thickness of a nonconductive coating by identifying the transition of material by a change in electrical properties. A slide-hold-slide test was conducted with a worn specimen including an electrodeposited coating layer. Relative displacement was imposed between a metallic stylus tip and a worn steel specimen. After an initial sliding, the tip was held for a certain time to measure electrical contact resistance. During the test, the vertical displacement of the stylus tip was also recorded to draw a surface profile of the worn specimen. Coating thickness on the specimen was determined with a surface profile at the transition of electrical contact conductance. Optical cross-section measurement of the specimen was applied to identify actual coating thickness. Measured results reveal that calculated coating thicknesses are in good agreement with measured values by an optical microscope. The proposed method allows determination of both nonconductive coating thickness and surface profile in a single measurement.

Sign in / Sign up

Export Citation Format

Share Document