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Floating structures, such as Spar platform, are likely to experience significant motions while operation due to Vortex-induced Motion (VIM). The main features of VIM include aspect ratio and mass r...

Overtopping breakwater for energy conversion (OBREC) is integration between breakwater and wave energy converter (WEC) that allows incoming waves to be stored in the reservoir. The higher the overtopping amount collected in a reservoir, the greater the energy generated will be. Hence, most of the overtopping concept has attempted to maximize the inclusion of water in the reservoir by optimizing geometrical parameters, particularly the ramp angle. However, the studies corresponding to ramp shapes geometries have not been adequately reviewed. Most studies only focused on the usage of linear overtopping ramp shape. There is still limited knowledge on the influence of different ramp shape parameters towards the overtopping wave. Thus, this paper aimed to push the border of available knowledge by investigating the influence of the ramp shape parameters to the overtopping wave discharge through simulation and experimenting approaches. Seven different ramp shapes have been tested under Malaysia&rsquo, s wave condition and a new ramp shape parameter allowing for maximized overtopping wave on OBREC is presented.

Introduction. Trawling is a method of catching fish in a large volume where fish nets are pulled through water using one or two boats. Bottom trawling is where the nets are pulled over on the seabed. The gear of the bottom trawling would impact the exposed subsea pipeline, on the seabed. Subsea pipelines transport crude oil and gas from the offshore platform to shore facility. This study assesses the risk of fish trawling activities to the subsea pipelines at Sabah and Labuan offshore. The specification of trawl equipment used by local trawlers in Sabah was determined by the on-site survey. The frequency of a fish trawler crossing over the pipelines was calculated based interview on operation and site survey. The calculation of the pull-over load of the otter board was calculated using the DNVGL algorithm. The severity and frequency index of the risk matrix was developed based on literature review. Results showed that the pull-over load of the otter board would not damage the pipelines. The risk posed by the fish trawler activity to the pipelines is low and moderate.

Reefing of Oil and Gas structure has become as one of the emerging options for decommissioning of an O&G Structure offshore and requires expert input beyond engineering such as biomarine and environmental sciences. This paper will present the interdisciplinary collaborative effort by industries with academia in Malaysia in developing a reef viability index as the first high level screening to assess the suitability of decommissioning using the reefing option in the region. The results of the reef viability index formulation to identify an offshore area that potential to be used for Rigs-to-Reefs (RTR) program in the South China Sea. The integration of data collection, numerical modelling and Geographic Information System (GIS) aims to review the relationship of coral reefs spawning ground, diversity and planula larvae in the colonization process which to produce a reefing area map. Coral connectivity and spawning behaviour were investigated to reveal the potential source of coral seedling as well as the number of coral larvae based on different taxa released during the spawning seasons. A spatial reef viability index was developed based on seven parameters, i.e. coral larval density, pelagic larval duration, sea currents, temperature, chlorophyll-a, depth, and substrate availability. Hydrodynamic model was developed to emulate the pattern of larval scattering. Based on the simulation and rankings, there were 95 (21%) sites that are most likely for in-situ reefing while the remaining 358 (79%) sites were probably suitable for ex-situ reefing or decommissioning. Validation of the viability index was done using Remotely Operated Vehicle (ROV) media footage assessment.

This research aims to investigate the influence of soil engineering properties on the corrosion dynamic and to classify these properties according to the power law constants k and v. Fieldwork and laboratory tests were carried out to measure the metal loss influenced by soil properties. Results from fieldwork indicated moisture content as the most influential factor on metal loss. Principal component analysis classified moisture content into constant k, while plasticity index and particle size are grouped into constant v. Similar findings were also observed for laboratory tests. As a conclusion, this research has identified moisture content as the most significant governing factor on constant k, while other soil properties have strong to modest influence on constant v. This research also reveals the existence of an optimum value of soil properties that influence the highest measured corrosion rate. This finding is significant and may change the way researcher model corrosion behaviour.

Offshore structures are exposed to random wave loading in the ocean environment, and hence the probability distribution of the extreme values of their response to wave loading is required for their safe and economical design. In most cases, the dominant load on offshore structures is due to wind-generated random waves where the ocean surface elevation is defined using appropriate ocean wave energy spectra. Several spectral models have been proposed to describe a particular sea state that is used in the design of offshore structures. These models are derived from analysis of observed ocean waves and are thus empirical in nature. The spectral models popular in the offshore industry include Pierson-Moskowitz spectrum and JONSWAP spectrum. While the offshore industry recognizes that different methods of simulating ocean surface elevation lead to different estimation of design wave height, no systematic investigation has been conducted. Hence, the aim of this study is to investigate the effects of predicting the 100-year responses from various wave spectrum models. In this paper, the Monte Carlo time simulation (MCTS) procedure has been used to compare the magnitude of the 100-year extreme responses derived from different spectral models. Additionally, the linear random wave theory (LRWT) was implemented to simulate the offshore structural responses due to random wave loading. The models have been tested for three different environmental conditions represented by Hs = 15m, 10m and 5m respectively. The accuracy of the predictions of the 100-year responses from Pierson-Moskowitz and JONSWAP spectrums will then be investigated.

This paper presents a computational fluid dynamics (CFD) study of vortex-induced vibration (VIV) for different aspect ratio (L/D) cylinder. Of particular interest was to measure hydrodynamic forces and numerically investigate the wake behaviour of VIV while varying the aspect ratio. The simulation models represented the actual experimental conditions with idealised free-surface boundary condition to capture the responses from fluid-structure interaction phenomenon. The simulations were performed in the subcritical flow region (7.4×103 < Re < 2×105), corresponding to a range of reduced velocity (Ur) from 2 to 14. The results of the cases studied were discussed and compared with the experimental data to verify the accuracy and validity of the present simulation. The comparisons have shown a similar curved-shape drag coefficient plot, and however underestimated the value of the drag coefficients over the reduced velocity. Additionally, the simulations seemed to capture a higher lift force response compared w...