Mooring observations and numerical modeling of thermal structures in the South China Sea

2010 ◽  
Vol 115 (C10) ◽  
Author(s):  
Ya-Ting Chang ◽  
Tswen Yung Tang ◽  
Shenn-Yu Chao ◽  
Ming-Huei Chang ◽  
Dong S. Ko ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Thermal Structures

Motion Characteristic Analysis of a Floating Structure in the South China Sea Based on Prototype Monitoring

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Wen-Hua Wu ◽  
Da Tang ◽  
Xiao-Wei Cui ◽  
Shi-Sheng Wang ◽  
Jia-Guo Feng ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
Characteristic Analysis ◽  
Structural Dynamic ◽  
Environmental Loading ◽  
China Sea ◽  
Motion Responses

Due to the complexity of ocean environmental loading models and the nonlinearity and empirical parameters involved in hydrodynamic numerical modeling and model testing, many uncertainties still exist in the design and operation of floating platforms. On-site prototype measurements provide a valid strategy for obtaining accurate environmental loading parameters and floater motion responses. A prototype monitoring system was built as part of a joint industrial project in the South China Sea. Long-term ocean environmental loading parameter data and structural dynamic motion responses were collected from 2012 to the present. In this study, the dynamic motions of the platform structure were analyzed using an artificial neural network (ANN) and data obtained during a typhoon. Numerical modeling was performed to analyze the platform parameters using a radial basis function (RBF), and hydrodynamic modeling was conducted using ansys-aqwa. Five geometric parameters related to the platform design were selected for optimization and included the mass, moments of inertia of the three rotation degrees, and the position of the center of gravity (COG). The mean values of the surge and pitch and the standard deviations of the roll and pitch were used as the input parameters. The model validations showed that the proposed ANN-based method performed well for obtaining the optimal platform parameters. The maximum errors of the roll, pitch, surge, and sway motions were within 5%. The updated response amplitude operators (RAOs) and new design indices for a 100-year return period of a typhoon were determined to guide operations and evaluate platform designs.

Motion Characteristic Analysis of a Floating Structure in the South China Sea Based on Prototype Monitoring

2017 ◽  
Author(s):  
Wen-hua Wu ◽  
Xiao-wei Cui ◽  
Bai-cheng Lv ◽  
Shi-sheng Wang ◽  
Jia-guo Feng ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
Environmental Loading ◽  
Dynamic Motion ◽  
China Sea ◽  
Motion Responses ◽  
Jonswap Spectrum

Background: Due to the complexity of ocean environmental loading models, together with the nonlinearity and empirical parameters involved in hydrodynamic numerical modeling and model testing, many uncertainties and challenges still exist in the design and operation of platforms built to float at sea. On-site prototype measurements carried out on actual floating structures provide a valid strategy for obtaining accurate environmental loading parameters and floater motion responses. Problem definition: A prototype monitoring system has been built as part of a joint industrial project in the South China Sea. A complete set of long-term ocean environment loading parameters and structural dynamic motion responses has been gathered for the period from 2012 to the present. Several advanced techniques, such as the independent remote monitoring technique (IRMT), the integrated continuous measurement technique and the standalone underwater measurement technique were established to enhance the reliability of data collection even during extreme typhoon conditions when there was no power. Solution approach and findings: this paper analyzes the dynamic motion characteristics of the platform structure based on the monitoring data. The relationship between the measured wave spectrum and the JONSWAP spectrum is discussed. The spectral shape parameters of the JONSWAP spectrum for the South China Sea, as derived from the monitoring data, are discussed. The dynamic motions of the platform structure are analyzed based on artificial neural networks (ANN) using data from a typical monitored typhoon. The numerical modeling used in this research is constructed to perform the identification analysis of the platform parameters using radius basic function (RBF) and hydrodynamic results produced by ANSYS-AQWA. This research selects five main geometric parameters related to the platform design. Mass, moments of inertia of three rotation degrees, and the position of the center of gravity (COG) are selected as the optimization objectives. The mean values of surge and pitch and standard deviations of roll and pitch are treated as the input parameters. Modeling verifications show that the present ANN-based method performs well in obtaining the optimal platform parameters. The maximum error between the simulated and monitored results in terms of the measurement of the roll, pitch, surge and sway motions fall within 5%. The model of the monitored platform could be further updated; it could be made capable of performing the performance assessments of the dynamic characteristics in extreme and/or harsh environmental conditions.

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