scholarly journals WAVE MEASUREMENTS BY A PRESSURE TYPE WAVE GAUGE

1968 ◽  
Vol 1 (11) ◽  
pp. 3 ◽  
Author(s):  
P.O Bergan ◽  
A. Torum ◽  
A. Tratteberg
Keyword(s):  
Wave Height ◽  
Wave Theory ◽  
Wave Spectra ◽  
First Order ◽  
Considerable Error ◽  
Type Wave ◽  
Wave Measurements ◽  
Continuous Wire ◽  
Wave Conditions

The paper deals with comparative measurements of irregular model waves by a pressure type wave gauge and a continuous wire wave gauge. For the depth and wave conditions used in the study it is concluded that the height of individual waves obtained by a pressure type gauge and using the first order wave theory may be in considerable error, while wave height distributions and wave spectra are fairly good estimated.

scholarly journals SECOND ORDER THEORY OF MANOMETER WAVE MEASUREMENT

1982 ◽  
Vol 1 (18) ◽  
pp. 8
Author(s):  
F. Biesel
Keyword(s):  
Gravity Wave ◽  
Wave Theory ◽  
Order Theory ◽  
Second Order ◽  
Order Effects ◽  
Mean Values ◽  
Surface Level ◽  
First Order ◽  
Wave Measurements ◽  
Wave Measurement

The paper refers to pressure gage wave measurements . First order transformation of the pressure spectrum into a surface level spectrum leads to hitherto unexplained discrepancies with prototype simultaneous pressure and level measurements . Use of second order gravity wave theory allows to draw the following conclusions » Second order effects appear to give a reasonable explanation of the observed discrepancies . A complete check would require specially made wave measurements and analyses . Second order corrections do not significantly affect mean values, such as significant height, if the manometer depth is not unduly large.

scholarly journals NEAR-BOTTOM CURRENT MEASURED BY ACOUSTIC SENSORS

1978 ◽  
Vol 1 (16) ◽  
pp. 50
Author(s):  
K.A. Selanger ◽  
T. Carstens
Keyword(s):  
Wave Theory ◽  
Current Data ◽  
Bottom Current ◽  
Acoustic Sensors ◽  
Current Profile ◽  
Vertical Transfer ◽  
First Order ◽  
Wave Measurements ◽  
Sea Bottom ◽  
Measuring Site

A vertical current profile has been measured with three acoustic meters 60 cm, 100 cm and 200 cm from the sea bottom. The depth at the measuring site was 84 metres. The profile is found to depend on the time scale of the water particle motion. An Ekman-like turning of the current is also observed, and the thickness of friction layers is estimated. Comparison of the current data with wave measurements indicates that the vertical transfer of surface wave energy is 30-50 per cent less than first order wave theory prescribes.

scholarly journals Investigation of Ocean-Wave-Focusing Characteristics Induced by a Submerged Crescent-Shaped Plate for Long-Crested Waves

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 509 ◽  
Author(s):  
Chi-Yu Li ◽  
Ruey-Syan Shih ◽  
Wen-Kai Weng
Keyword(s):  
Wave Height ◽  
Incident Wave ◽  
Wave Energy ◽  
Wave Theory ◽  
Wave Focusing ◽  
Wave Energy Converters ◽  
Potential Applications ◽  
Wave Conditions ◽  
Wave Farm ◽  
Incident Waves

The need for renewable energy has gained importance with growing concerns about climate change. Wave energy has attracted considerable attention owing to its sustainability potential. Reflection, refraction, diffraction, and shoaling of waves occur when waves propagate through a submerged structure. These mechanics, when properly utilized, can be employed to focus waves to a specific location and also to increase wave heights, by which wave energy is usually represented, for planning and designing wave farms. Wave focusing induced by a submerged crescent-shaped plate for different wave conditions, incident wave directions, and submerged depths mainly considering the potential applications of absorber wave-energy converters within the wave farm was investigated experimentally and numerically. All experimental regular wave conditions were controlled to be nonbreaking, and the numerical results were obtained by a 3D model, implemented through the boundary element method based on Airy wave theory. The results show that wave focusing appears behind the plate along the direction of the incident waves, and the locations of focused waves tend to be farther away from the plate for shorter-period waves. The maximum measured wave height can be 3.44 times higher than the incident wave height.

scholarly journals EXTREME WAVE CONDITIONS IN BRITISH AND ADJACENT WATERS

1972 ◽  
Vol 1 (13) ◽  
pp. 6 ◽  
Author(s):  
Laurence Draper
Keyword(s):  
Wave Height ◽  
Offshore Structures ◽  
Wave Period ◽  
The Other ◽  
Wind Data ◽  
Extreme Wave ◽  
Wave Measurements ◽  
Extreme Wind ◽  
Wave Conditions

Information on extreme wave conditions is needed in the design of offshore structures. This paper present the results of calculations of the parameters in the 50-year storm; the work has been based on extreme wind data and on instrumental wave measurements. The results are complementary, and are combined in two maps, one of extreme wave height and the other of the corresponding wave period.

Cased borehole acoustic-wave propagation with varying bonding conditions: Theoretical and experimental modeling

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. D161-D169
Author(s):  
Can Jiang ◽  
Xue-Lian Chen ◽  
Yuan-Da Su ◽  
Xiao-Ming Tang
Keyword(s):  
Acoustic Wave ◽  
Wave Theory ◽  
Acoustic Measurements ◽  
Acoustic Wave Propagation ◽  
Velocity Change ◽  
Slip Boundary ◽  
Wave Measurements ◽  
Bonding Condition ◽  
Bond Evaluation ◽  
Cased Borehole

Acoustic measurements in cased boreholes are important for cement-bond evaluation behind the casing. In conjunction with a recently developed acoustic-wave theory using slip-boundary modeling, we carried out an experimental study for different cement-bond conditions. Four different cased-hole models were constructed, where the interface between the casing and the cement, and that between the cement and the formation, are decoupled or partially bonded to simulate the different cement bond conditions. An acoustic system is placed in the borehole to measure extensional casing waves along the borehole. By extracting the attenuation and velocity of casing waves from the experimental data, the bonding conditions were analyzed and compared with the theoretical modeling. The results indicate that, compared with the free-pipe situation, the casing waves are attenuated when there is some degree of bonding (good or poor) between the casing and the formation. However, when the poor bonding occurs at the cement-formation interface, the casing wave indicates significant velocity reduction and dispersion, the degree of the velocity change varying with the bonding condition. This wave phenomenon is predicted by the slip-boundary modeling. By adjusting the slip-boundary parameters in the modeling, the experimental results can be quantitatively modeled. These results are also confirmed by cased-hole acoustic logging data examples. The theoretical model can therefore be used to interpret cased-borehole acoustic-wave measurements.

scholarly journals LABORATORY SIMULATIONS OF WAVE ATTENUATION BY AN EMERGENT VEGETATION OF ARTIFICIAL PHRAGMITES AUSTRALIS: AN EXPERIMENTAL STUDY OF AN OPEN-CHANNEL WAVE FLUME

2015 ◽  
Vol 23 (4) ◽  
pp. 251-266 ◽  
Author(s):  
Li YIPING ◽  
Desmond Ofosu ANIM ◽  
Ying WANG ◽  
Chunyang TANG ◽  
Wei DU ◽  
...  
Keyword(s):  
Experimental Study ◽  
Phragmites Australis ◽  
Wave Height ◽  
Plant Density ◽  
Wave Attenuation ◽  
Emergent Vegetation ◽  
Irregular Waves ◽  
Shore Protection ◽  
Near Shore ◽  
Wave Conditions

This paper presents a well-controlled laboratory experimental study to evaluate wave attenuation by artificial emergent plants (Phragmites australis) under different wave conditions and plant stem densities. Results showed substantial wave damping under investigated regular and irregular wave conditions and also the different rates of wave height and within canopy wave-induced flows as they travelled through the vegetated field under all tested conditions. The wave height decreased by 6%–25% at the insertion of the vegetation field and towards the downstream at a mean of 0.2 cm and 0.32 cm for regular and irregular waves respectively. The significant wave height along the vegetation field ranged from 0.89–1.76 cm and 0.8–1.28 cm with time mean height of 1.38 cm and 1.11 cm respectively for regular and irregular waves. This patterns as affected by plant density and also location from the leading edge of vegetation is investigated in the study. The wave energy attenuated by plant induced friction was predicted in terms of energy dissipation factor (fe) by Nielsen’s (1992) empirical model. Shear stress as a driving force of particle resuspension and the implication of the wave attenuation on near shore protection from erosion and sedimentation was discussed. The results and findings in this study will advance our understanding of wave attenuation by an emergent vegetation of Phragmites australis, in water system engineering like near shore and bank protection and restoration projects and also be employed for management purposes to reduce resuspension and erosion in shallow lakes.

The Wave Theory of the Electron

1928 ◽  
Vol 24 (4) ◽  
pp. 501-505 ◽  
Author(s):  
J. M. Whittaker
Keyword(s):  
Wave Function ◽  
Differential Equations ◽  
Fourth Order ◽  
Commutative Algebra ◽  
Wave Theory ◽  
Wave Functions ◽  
Linear Differential Equations ◽  
Wave Mechanics ◽  
First Order ◽  
Linear Differential

In two recent papers Dirac has shown how the “duplexity” phenomena of the atom can be accounted for without recourse to the hypothesis of the spinning electron. The investigation is carried out by the methods of non-commutative algebra, the wave function ψ being a matrix of the fourth order. An alternative presentation of the theory, using the methods of wave mechanics, has been given by Darwin. The four-rowed matrix ψ is replaced by four wave functions ψ1, ψ2, ψ3, ψ4 satisfying four linear differential equations of the first order. These functions are related to one particular direction, and the work can only be given invariance of form at the expense of much additional complication, the four wave functions being replaced by sixteen.

scholarly journals WAVE MEASUREMENTS IN OPEN OCEAN

1976 ◽  
Vol 1 (15) ◽  
pp. 6
Author(s):  
Davidson T. Chen ◽  
Benjamin S. Yaplee ◽  
Donald L. Hammond ◽  
Paul Bey
Keyword(s):  
Water Pressure ◽  
Open Ocean ◽  
Ocean Wave ◽  
Naval Research ◽  
Wave Spectra ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Wave Measurements ◽  
Microwave Sensor ◽  
Low Pass

The ability to measure the wave spectra in the open ocean from a moving vessel has met with varying degrees of success. Each sensor to date has suffered in its performance due to environmental conditions or due to its physical placement aboard the vessel for measuring the unperturbed sea. This paper will discuss the utilization of a microwave sensor on a moving vessel for measuring the open ocean wave spectra. Employing microwaves, some of the limitations of other sensors are not experienced. Tucker [1] developed the Tuckermeter for measuring the wave spectra from a moving ship by sensing changes in water pressure due to surface wave conditions. The Tuckermeter is placed below the water line and thus requires calibration for each wave frequency, ship speed, and depth. Since the sensor operates on pressure, it performs as a low pass filter and will not sense the higher frequencies. A microwave shipboard wave height radar sensor for measuring the ocean wave spectra was developed by the Naval Research Laboratory (NRL) and was installed on the S.S. McLean in February 1975 and its performance, design, and analysis of data for one data run will be discussed.

Simulation of Hurricane Seas in a Multidirectional Wave Basin

1991 ◽  
Vol 113 (3) ◽  
pp. 219-227 ◽  
Author(s):  
A. Cornett ◽  
M. D. Miles
Keyword(s):  
Ocean Waves ◽  
Entropy Method ◽  
Wave Spectra ◽  
Single Wave ◽  
Wave Condition ◽  
Wave Basin ◽  
Wide Range ◽  
Directional Wave ◽  
Wave Conditions ◽  
Multidirectional Wave

This paper describes the generation and verification of four realistic sea states in a multidirectional wave basin, each representing a different storm wave condition in the Gulf of Mexico. In all cases, the degree of wave spreading and the mean direction of wave propagation are strongly dependent on frequency. Two of these sea states represent generic design wave conditions typical of hurricanes and winter storms and are defined by JONSWAP wave spectra and parametric spreading functions. Two additional sea states, representing the specific wave activity during hurricanes Betsy and Carmen, are defined by tabulated hindcast estimates of the directional wave energy spectrum. The Maximum Entropy Method (MEM) of directional wave analysis paired with a single-wave probe/ bi-directional current meter sensor is found to be the most satisfactory method to measure multidirectional seas in a wave basin over a wide range of wave conditions. The accuracy of the wave generation and analysis process is verified using residual directional spectra and numerically synthesized signals to supplement those measured in the basin. Reasons for discrepancy between the measured and target directional wave spectra are explored. By attempting to reproduce such challenging sea states, much has been learned about the limitations of simulating real ocean waves in a multidirectional wave basin, and about techniques which can be used to minimize the associated distortions to the directional spectrum.

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