scholarly journals NEAR-SURFACE ORBITAL VELOCITIES IN IRREGULAR WAVES

1986 ◽  
Vol 1 (20) ◽  
pp. 8
Author(s):  
K.-F. Daemrich ◽  
A. Gotschenberg
Keyword(s):  
Wave Theory ◽  
Surface Elevation ◽  
Irregular Waves ◽  
Linear Wave ◽  
Simulation Methods ◽  
Servo Motor ◽  
Near Surface ◽  
Linear Wave Theory ◽  
Wave Flume

The paper deals with measurements of horizontal orbital velocities near the surface of mechanically generated waves in a wave flume. Due to the characteristics of most velocity probes, it is difficult or impossible to measure with a fixed probe in the area above the lowest trough. As the probe is not submerged continuously, failures or uncertainties in the measurements may occur. To overcome these limitations, a movable frame for the velocity probe was designed, which can be moved vertically up and down with the surface elevation by a disc rotor servo motor, controlled by a wave gauge. By that continuously velocities up to 3 cm below the surface could be measured. Theoretical velocities have been calculated for comparison with different simulation methods for irregular waves, based on linear wave theory.

scholarly journals INVESTIGATIONS ON ORBITAL VELOCITIES AND PRESSURES IN IRREGULAR WAVES

1982 ◽  
Vol 1 (18) ◽  
pp. 20
Author(s):  
K.F. Daemrich ◽  
W.D. Eggert ◽  
H. Cordes
Keyword(s):  
Frequency Domain ◽  
Water Surface ◽  
Wave Theory ◽  
Hydraulic Model ◽  
Irregular Waves ◽  
Linear Wave ◽  
Simulation Methods ◽  
Linear Wave Theory ◽  
Theoretical Results

This paper deals with the results of hydraulic model investigations of orbital velocities and pressures in irregular waves. Different simulation methods in the time and frequency domain were checked or developed, and the theoretical results compared with measurements. Using simulation methods based on linear wave theory, results with good correlation are obtained, at locations near the water surface, however, a tendency towards over- or underestimation exists.

scholarly journals INVESTIGATIONS ON IRREGULAR WAVES IN HYDRAULIC MODELS

1980 ◽  
Vol 1 (17) ◽  
pp. 10 ◽  
Author(s):  
Karl-Friedrich Daemrich ◽  
Wolf-Dietrich Eggert ◽  
Soren Kohlhase
Keyword(s):  
Time Domain ◽  
Transfer Functions ◽  
Wave Theory ◽  
Irregular Waves ◽  
Linear Wave ◽  
Simulation Methods ◽  
Mechanical Wave ◽  
Theoretical Simulation ◽  
Linear Wave Theory ◽  
Signal Characteristics

The first part of the paper deals with some aspects of wave generation by mechanical wave-generators, especially with hydraulic transfer functions for pusher movement of the paddle, and the influences of signal characteristics and analysis methods. In the second part, results of measurements of orbital velocities and pressures in irregular waves are presented, together with some results from theoretical simulation methods in the frequency and time domain, based on linear wave theory.

Numerical Non-Reflecting Irregular Wave Flume Based on VOF Method

2009 ◽  
Author(s):  
Bing Ren ◽  
Xuelin Li ◽  
Peng Han ◽  
Yongxue Wang
Keyword(s):  
Wave Theory ◽  
Vof Method ◽  
Numerical Results ◽  
Irregular Waves ◽  
Open Boundary ◽  
Linear Wave ◽  
Reflected Waves ◽  
Irregular Wave ◽  
Wave Flume ◽  
Sponge Layer

A numerical irregular wave flume is developed using VOF method in conjunction with Reynolds equations. An active absorbing wave-maker based on linear wave theory is set on the left boundary of the wave flume to absorb the re-reflected waves. A sponge layer is set on the open boundary to absorb the outgoing waves. The numerical results of regular and irregular waves using the active absorbing-generating boundary are compared to the numerical results using the ordinary generating boundary to verify the performance of the active absorbing-generator boundary. The linear damping coefficient is used in the sponge layer. The damping characteristics of the sponger layer implemented in the wave flume are discussed. The computed wave spectra are compared with the target spectra.

scholarly journals ORBITAL VELOCITIES IN IRREGULAR WAVES

1980 ◽  
Vol 1 (17) ◽  
pp. 9 ◽  
Author(s):  
F.C. Vis
Keyword(s):  
Time Domain ◽  
Wave Motion ◽  
Theoretical Study ◽  
Impulse Response Function ◽  
Wave Theory ◽  
Irregular Waves ◽  
Linear Wave ◽  
Response Functions ◽  
Linear Wave Theory ◽  
Response Function Method

Experimental and theoretical study to determine the applicability of linear wave theory for the description of the velocity field in irregular waves. A comparison between theory and measurement was executed both in frequency and in time domain. In frequency domain by means of the experimentally and theoretically determined frequency response functions of wave motion to orbital velocity, and in time domain by means of the measured and computed time records of the velocities. The time records for the velocities were computed from the measured waterlevel fluctuations by using the impulse response function method. The orbital velocities were measured contactless with laser-doppler equipment.

Nonlinear Waves in Strings: The Barrage Balloon Problem

1998 ◽  
Vol 65 (1) ◽  
pp. 141-149
Author(s):  
J. F. Hall
Keyword(s):  
World War Ii ◽  
Nonlinear Waves ◽  
Wave Reflection ◽  
Wave Theory ◽  
P Wave ◽  
Linear Wave ◽  
Geometrically Nonlinear ◽  
World War ◽  
Linear Wave Theory ◽  
Important Solution

This paper develops a theory for geometrically nonlinear waves in strings and presents analytical solutions for a traveling kink, generation of a geometric wave with its accompanying P wave, reflection of a kink at a fixed support and at a smooth sliding support, and interaction of a P wave and a kink. Conditions that must be satisfied for linear wave theory to hold are derived. The nonlinear theory is demonstrated by extending an historically important solution of the barrage balloon problem that was obtained during World War II.

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