Experimental investigation of the airflow structure above mechanically generated regular waves for both aligned and opposed wind-wave directions

2022 ◽  
pp. 110578
Author(s):  
Sara Porchetta ◽  
Tommaso Carlesi ◽  
Maria Rosaria Vetrano ◽  
Jeroen van Beeck ◽  
Delphine Laboureur
Keyword(s):  
Experimental Investigation ◽  
Wind Wave ◽  
Regular Waves

Experimental Investigation of Vortex-Induced Vibrations of a Flexibly Mounted Circular Cylinder in Combined Current and Wave Flows

2021 ◽  
Author(s):  
Pierre-Adrien Opinel ◽  
Narakorn Srinil
Keyword(s):  
Experimental Investigation ◽  
Circular Cylinder ◽  
Cross Flow ◽  
Wave Flow ◽  
Regular Wave ◽  
Regular Waves ◽  
Vortex Induced Vibrations ◽  
Flow Frequency ◽  
The Cross ◽  
Wave Flows

Abstract This paper presents the experimental investigation of vortex-induced vibrations (VIV) of a flexibly mounted circular cylinder in combined current and wave flows. The same experimental setup has previously been used in our previous study (OMAE2020-18161) on VIV in regular waves. The system comprises a pendulum-type vertical cylinder mounted on two-dimensional springs with equal stiffness in in-line and cross-flow directions. The mass ratio of the system is close to 3, the aspect ratio of the tested cylinder based on its submerged length is close to 27, and the damping in still water is around 3.4%. Three current velocities are considered in this study, namely 0.21 m/s, 0.29 m/s and 0.37 m/s, in combination with the generated regular waves. The cylinder motion is recorded using targets and two Qualisys cameras, and the water elevation is measured utilizing a wave probe. The covered ranges of Keulegan-Carpenter number KC are [9.6–35.4], [12.8–40.9] and [16.3–47.8], and the corresponding ranges of reduced velocity Vr are [8–16.3], [10.6–18.4] and [14–20.5] for the cases with current velocity of 0.21 m/s, 0.29 m/s and 0.37 m/s, respectively. The cylinder response amplitudes, trajectories and vibration frequencies are extracted from the recorded motion signals. In all cases the cylinder oscillates primarily at the flow frequency in the in-line direction, and the in-line VIV component additionally appears for the intermediate (0.29 m/s) and high (0.37 m/s) current velocities. The cross-flow oscillation frequency is principally at two or three times the flow frequency in the low current case, similar to what is observed in pure regular waves. For higher current velocities, the cross-flow frequency tends to lock-in with the system natural frequency, as in the steady flow case. The inline and cross-flow cylinder response amplitudes of the combined current and regular wave flow cases are eventually compared with the amplitudes from the pure current and pure regular wave flow cases.

Experimental Investigation on the Dynamic Response of an Internal Turret Moored FPSO System Under Sea Waves

2003 ◽  
Author(s):  
T. Rajesh Kannah ◽  
R. Natarajan
Keyword(s):  
Experimental Investigation ◽  
Dynamic Behaviour ◽  
Operating Conditions ◽  
Scale Model ◽  
Sea Waves ◽  
Regular Waves ◽  
Wave Flume ◽  
Load Cells ◽  
Mooring Forces ◽  
Rotary Type

An experimental investigation on the dynamic behaviour of a typical internal turret moored FPSO system with a turret located at midships position is reported. A 1:100 scale model of 140000t DWT turret moored FPSO system was tested under regular waves for three operating conditions i.e. 40%DWT, 70%DWT and 100%DWT in a 2m wide wave flume at a water depth of 1m for the wave frequencies from 0.55Hz to 1.25Hz in steps of 0.04Hz. The motions were measured by rotary type potentiometers and specially ring type load cells were used to measure the mooring forces. The model tests results are analysed and presented with discussions in this paper.

Effect of Porous Baffle on Sloshing Dynamics in a Barge Mounted Container Subjected to Wave Excitation

2017 ◽  
Author(s):  
Nasar Thuvanismail ◽  
Akshay P. Shah ◽  
Deepak J. Surahonne ◽  
Sannasiraj S. Annamalaisamy
Keyword(s):  
Experimental Investigation ◽  
Aspect Ratio ◽  
Water Level ◽  
Excitation Frequency ◽  
Experimental Setup ◽  
Regular Wave ◽  
Wave Excitation ◽  
Regular Waves ◽  
Sloshing Dynamics

An experimental investigation was carried out to determine the effect of porous baffle walls on sloshing dynamics of a sloshing tank that is partially filled with liquid and rigidly mounted in a barge. The experimental setup is subjected to beam sea regular wave excitations and hence the barge experiences combined sway heave and roll excitations. An aspect ratio (hs/l, where hs is still water level and l is length of tank) of 0.488 is considered which corresponds to 75% fill condition with respect to tank height. Three porosities of 15%, 20%, and 25% are considered. The barge system was subjected to regular waves of frequency (fw) ranging from 0.45Hz to 1.54Hz. The effectiveness of porous baffles on the dissipation of sloshing energy is studied in comparison with without baffle condition. The effect of wave excitation frequency on the sloshing dynamics has also been analysed and the prominent results are here in reported.

Experimental investigation on turning characteristics of KVLCC2 tanker in regular waves

2019 ◽  
Vol 175 ◽  
pp. 197-206 ◽  
Author(s):  
Dong Jin Kim ◽  
Kunhang Yun ◽  
Jong-Yong Park ◽  
Dong Jin Yeo ◽  
Yeon Gyu Kim
Keyword(s):  
Experimental Investigation ◽  
Regular Waves

Experimental Investigation of the Nonlinear Effects on the Vertical Motions and Loads of a Containership in Regular Waves

2004 ◽  
Vol 48 (02) ◽  
pp. 118-147 ◽  
Author(s):  
N. Fonseca ◽  
C. Guedes Soares
Keyword(s):  
Experimental Investigation ◽  
Wave Amplitude ◽  
Nonlinear Effects ◽  
Wave Frequency ◽  
Experimental Program ◽  
Regular Waves ◽  
Cross Sectional ◽  
Nonlinear Characteristics ◽  
Time Histories ◽  
Vertical Accelerations

The nonlinear vertical responses of a containership advancing in regular waves are investigated experimentally. The paper presents the results of an experimental program carried out in a seakeeping tank with a model of the ITTC S-175 containership in head regular waves. All the wave frequency ranges of interest were tested, and for each wave frequency several wave amplitudes were used ranging from small to large amplitude. In this way the influence of the wave amplitude on the nonlinear characteristics of the responses was assessed. The measured responses include the absolute and relative motions, vertical accelerations, and cross-sectional loads at midship and ¼ Lpp from the forward perpendicular. Strong nonlinear effects were detected, especially on the loads, which can be identified by the variation of the transfer function with the wave amplitude, the asymmetry of the time histories, and the presence of higher harmonics.

scholarly journals HORIZONTAL AND VERTICAL WATER PARTICLE VELOCITIES INDUCED El WAVES

1972 ◽  
Vol 1 (13) ◽  
pp. 27
Author(s):  
Yoshito Tsuchiya ◽  
Masataka Yamaguchi
Keyword(s):  
Particle Velocity ◽  
Wind Wave ◽  
Wind Waves ◽  
Power Spectra ◽  
Surface Displacement ◽  
Ocean Waves ◽  
Regular Waves ◽  
Water Particle ◽  
Cross Correlations ◽  
Particle Velocities

Measurements of horizontal and vertical water particle velocities induced by regular waves, wind waves generated by a wind wave tank and ocean waves in shallow water were made using a Doppler-type sonic current meter. For regular waves, the validity of wave theories such as Stokes and cnoidal waves is investigated by comparison between theoretical curves and the experimental results. For wind waves and ocean waves, power spectra of water particle velocities and cross-correlations between surface displacement and water particle velocity are considered, especially in the latter case, directional spectra calculated from both the records are compared each other.

scholarly journals NUMERICAL MODELLING OF BREAKER DEPTH INDEX

2017 ◽  
pp. 29
Author(s):  
Felice D'Alessandro ◽  
Giuseppe Tomasicchio ◽  
Giancarlo Chiaia ◽  
Francesco Ciardulli ◽  
Antonio Francone
Keyword(s):  
Experimental Investigation ◽  
Numerical Modelling ◽  
Wave Breaking ◽  
Large Scale ◽  
Fixed Bed ◽  
Wave Model ◽  
The Other ◽  
Regular Waves ◽  
Depth Index ◽  
Physical Data

The breaker depth index, γb, is commonly used to determine the wave height to water depth ratio where the wave will break (Horikawa, 1988). In the present study, γb has been calculated using a fully nonlinear Boussinesq Type Equations (BTE) wave model with implemented BCI (Breaking Celerity Index). The BCI is a phase-resolving type breaking criterion for calculating the incipient wave breaking conditions (D’Alessandro and Tomasicchio, 2008). The model suitability in predicting γb has been verified against physical data from an experimental investigation conducted with incident regular waves propagating along uniform 1:20 and 1:50 slope beaches (G.V. dos Reis, 1992), and estimates of γb from five existing empirical formulae (Battjes, 1974; Ostendorf and Madsen, 1979; Singamsetti and Wind, 1980; Smith and Kraus, 1990; Goda, 2010). The comparisons showed that BCI presents a better agreement with the physical data with respect to the other investigated formulae in determining the value of γb, independently from the breaker type. In addition, the verification of the BCI in determining γb has been extended to the observed data from a large-scale laboratory experiment on wave hydrodynamics performed over a fixed-bed barred beach (Tomasicchio and Sancho, 2002).

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