The response characteristics of the discus hull shaped data buoy under the influence of nonlinear wave conditions was studied in an experimental investigation. The measured wave elevation and the buoy response time histories were analyzed by phase-portraits as well as through the spectral representations. The details of the model, instrumentation, testing conditions and the analysis are presented and discussed in this paper. Copyright © 2008 by ASME.

V Sundar

Department of Ocean Engineering

Sannasi Annamalaisamy Sannasiraj

DATA BUOY

Experimental investigations

Non-linear response

Nonlinear waves

Response characteristic

Response time

SPECTRAL REPRESENTATIONS

TESTING CONDITIONS

WAVE ELEVATIONS

ARCTIC ENGINEERING

mechanics

Ocean Engineering

BUOYS

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE

This paper describes the development and performance validation of a cylindrical surface buoy (CSB) used for monitoring tsunamis in Indian seas. The buoy design with multiple compartments provides damage-tolerance curved top surface profile, the subsurface access ensures vandalism resistance, and the shape provides enough space for the power and control systems for an offshore endurance of two years. The scaled-down CSB is numerically modeled and experimentally validated for its stability in a wave basin. The validated numeric model is extended to a diameter of 2.4 m and the mooring loads are analyzed. The field scale prototype CSB is deployed in the open ocean, where the water depth is 2500 m. The performance of the CSB is validated from one year of failure-free performance and capability to remain within the watch circle under all environmental conditions, and it has detected the water level change events during the operational period. © 1976-2012 IEEE.

IEEE Journal of Oceanic Engineering

Development and Performance Validation of a Cylindrical Buoy for Deep-Ocean Tsunami Monitoring

Hydrodynamic response of a moored surface buoy has been experimentally evaluated in the present study. This buoy has been designed by National Institute of Ocean Technology (NIOT) to suit the functional requirements. A Froude scale model has been adopted and the floating body characteristics such as meta centric height has been preserved in the modeling. The sway, heave and roll responses have been measured using potentiometers and accelerometers under the action of regular and random waves. The frequency characteristics of the system have been reported. The stability of the buoy is verified for the wider scale of wave frequencies. © 2015 IEEE.

2015 IEEE Underwater Technology, UT 2015

Physical model testing of moored surface buoy

A load cell for the measurement of mooring forces is designed using the load-strain principles and the same is verified for its efficiency by structural modeling. A model load cell is fabricated and calibrated through laboratory experiments using three axes loading as well as mooring chain catenary principles. Experiments are also conducted in the physical wave tank to measure the mooring forces exerted on a disc shaped data buoy by using the designed load cell. The details of the design concepts, structural modeling, instrumentation, calibration, wave tank experiments and the results are discussed in this paper. © 2014, The Institution of Engineers (India).

Journal of The Institution of Engineers (India): Series C

A Load Cell for the Measurement of Slack Mooring Forces

Conventional data buoys record wave spectral parameters such as the significant height, peak period, and mean direction. Information about the existence of wave groups and breaking waves is also important for the design of ocean structures. To derive such information from data buoy measurements, understanding of the motion characteristics of data buoys under a variety of wave conditions is essential. In the present study, the motion characteristics of a scale-modelled discus data buoy were tested under the action of deep-water breaking waves of different intensities, covering spilling to steep plunging types. The laboratory generation of breaking waves was based on the constructive wave-wave interaction method. The buoy heave and pitch motions were measured using potentiometers and non-contact motion-capturing cameras. The measured time series of the breaking-wave surface elevation and the resulting buoy motions were analysed by continuous wavelet transformation and phase-time methods. A closer insight into the wavelet phases reveals that the breaking events leave a constant phase variation over a wider range of higher frequencies. Through appropriate filtering of the localized frequencies, the phase-time method could also be adopted to detect breaking events in the time histories of the measured wave elevation and motion response. The details of the model, instrumentation, testing conditions, and analysis are presented and discussed in this paper.

Proceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment

Identification of breaking events from the responses of a data buoy

A scale modeled discus data buoy was tested for its motion characteristics under the action of wave groups of different frequencies in a wave tank. The wave groups were theoretically simulated based on the methodology of Xu et&nbsp;al., (1993, Statistical simulation of wave groups, Applied Ocean Research, 15, 217-226) and then converted to paddle displacement signals to drive the wave maker. The motion responses of the buoy model were measured using potentiometers as well as with a non-contact motion tracking camera system. The details of the model, instrumentation, testing conditions and the analysis are presented. The displacement and wave elevation time histories were analysed through statistical, envelope, wavelet transform and phase-time approaches to detect the wave groupiness. The effect of groupiness parameters on the surge, heave and pitch motions of the buoy are detailed in this paper. © 2007 International Association for Hydraulic Engineering and Research, Asia Pacific Division.

Journal of Hydro-Environment Research

Detection of wave groups from the motion behaviour of a discus buoy

Nonlinear response characteristics of discus data buoy hull

Journal	Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE
Open Access	No