Floating breakwater becomes an alternative and reliable coastal area protection as it is cheaper in production cost as compared to conventional bottom-fixed breakwater. Floating breakwater system would be the best decision in order to control sedimentation that threatens the shore due to erosion. This study proposes to analyse Cylindrical Floating Breakwater (CFB) aimed at gaining a sufficient reduction in the sediment transport rate along the shore (case study at Tok Jembal Beach in Kuala Terengganu) by using CFD approach. Several parameters for the effects of wavelengths and vertical clearance between the CFB and seabed on the gradient of suspended and packed sediment were simulated by using Flow3D. A wave boundary was assigned to give an insight on regular waves effects to the parameters used in the simulation. The results showed that the presence of CFB markedly reduced the concentration and mass of suspended sand, gravel and coarse gravel for the whole range of wavelengths considered. Besides, it was found that varying the relative clearance of the floating breakwater and seabed was particularly sensitive to the concentration and mass of suspended sediment. Meanwhile, the bulk of sediment mass and concentration remain insignificant for the investigated wavelength and vertical clearance. From this standpoint, the cylindrical floating breakwater (CFB) could significantly minimise the gradient of sediment transport along the breakwater-beach distance while its installation depth may be optimised for circumstances to save cost, avoid breaking waves and morphological changes, ship traffic routes and etc.

Since the attribute of wave energy transmission is susceptible to lateral separation (S/D) between twin pontoons of floating breakwater (TPFB), arbitrarily selection of S/D may present problems in the evaluations on the effectiveness of the structure. This paper presents a numerical optimization modelling aimed at obtaining the optimum S/D through Genetic Algorithm (GA) approach. The artificial intelligence is primarily employed to minimize transmission of wave energy coefficients ( ) whereas maximize energy dissipation coefficient ( ). To achieve such demand, a numerical simulation implementing a MATLAB code as an interface between the Genetic Algorithm and a CFD program is applied. Several parameters for the effects of various wavelengths and ratios of S/D including a set of criteria have been considered in the simulation, where the optimum solution is chosen from various populations. The results demonstrated that the current GA analysis is efficient that can search a global trade-off between and to determine an optimum S/D ratio. For S/D equal to 2.72, minimized to less than 0.3 as compared to existing model ( > 0.5) while maximized to greater than 0.95 resulting to optimum hydrodynamic effects of TPFB. Hence, the optimization algorithm can serve as a useful engineering tool for a conceptual design to determine an optimum S/D for twin pontoon floating breakwater.

Attenuating waves by simple prismatic structures are increasingly recognised for coastal protection. Yet, evaluating their performance as good attenuators inevitably requires a reliable approach to adequately capture the dynamic interaction between waves and structure. This paper presents a prediction on hydrodynamic properties of pile-restrained cylindrical floating breakwater using computational fluid dynamics (CFD) approach. Several parameters for the effects of relative width (/) and relative draft (/) of the floating breakwater on the coefficient of transmission, reflection, and energy dissipation have been simulated using Flow3D. A wave boundary is assigned to give an insight into the regular and random wave effects to the parameters used in the simulation. The result revealed that the wave absorbing effect of CFB is apparently good, especially in high regular waves that considerably suppress the wave transmission. The higher energy dissipation than reflection characteristics suggests that the breakwater behaves effective as wave dissipator, especially for short waves. This attributed to the stiffness effect and in-plane damping across the vertical cage. From the practical views, the installation of the breakwater system into floating bridge or docks with limited rolls is satisfactory for perimeter protection specifically in the coastal zone of peninsular Malaysia.

Due to the increasing of fuel prices and volatile of environmental regulations, it is a challenge for Naval Architects to design a ship dealing with an optimum ship’s total resistance. The conventional design of catamaran hull has not satisfied yet to reduce the ship’s total resistance. This paper presents a numerical investigation into gaining sufficient reduction of the ship’s total resistance of catamaran through optimizing her hull form. To achieve this research objectives, a numerical optimization modelling coupled with a Computational Fluid Dynamics (CFD) approach has been successfully conducted. Several parameters such as length, beam and draft of catamaran hull have been taken into account towards reducing the ship’s total resistance. Here, the simulation constraints are applied to obtain the optimum dimension, where the length, beam and draft of the catamaran hull were optimized within the range of 1.2 m to 1.5 m, 0.11 m to 0.14 m and 0.07 m to 0.08 m, respectively. In general, the optimization simulation revealed that the optimum dimension of the catamaran hull resulted in reduction of the total ship’s resistance. The results showed that the optimum length, beam and draft of hull led to reduce by 21.08%, 16.95% and 17.91%, respectively. Merely, this numerical optimization simulation provides a useful way for reducing the total ship’s resistance of the catamaran at the preliminary design stage.

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