Papers by Keyword: Wave Force

Abstract: The purpose of this research work is to study the hydrodynamic characteristics of a new type of artificial reef structure, in order to provide a structure with low flow resistance, which will be a more suitable shelter for fishes and marine organisms. The idea of the new artificial reef is based on the streamlined bicycle helmet design concept. The hydrodynamic characteristics of the helmet and hollow cube artificial reefs (ARs) of the same volume have been studied at different water depths and wave frequencies of Malaysia seas using Computational Fluid Dynamics (CFD) method. The finite volume RANSE (Reynolds-Averaged Navier-Stokes Eqs.) code Ansys CFX was used for calculating the reefs drag force (F_D) and flow characteristics, while the potential flow code Ansys Aqwa was used for calculating the reefs inertia force (F_I). The Shear Stress Transport (SST) turbulence model was used in the RANSE code. The results of the two ARs were then compared for studying the hydrodynamic improvement due to the use of streamlined helmet artificial reef on the flow pattern around it. The streamlined body of the helmet artificial reef enhances the flow pattern at the aft region of the reef and provides flow zones with moderate flow speed at this area, which can help fishes and marine organisms from finding good shelter. The special shape of the different openings in the body of the helmet artificial reef improves the condition of the flow velocity distribution inside the unit than that of the hollow cube unit, which can increase the amount of the nutrient to the living fishes and organisms inside the reef.

Abstract: By taking the 3D Laplace equation as the basic governing equation, a mathematical model with respect to the interaction between linear waves and arbitrary 3D structures was founded. With an example of wave action with four cylinders, numerical results show that when incident wave direction is 22.5°, wave force F_x on 1# cylinder and 2# cylinder is the biggest and when incident wave direction is 0°, wave force F_x on 3# cylinder and 4# cylinder is the biggest; wave force F_y and the wave height on origin point increases with incident wave direction increasing for the given layout and incident wave conditions.

Abstract: The high-pile wharf near estuary under wave subjects to great wave force. The wave force can cause destruction of the wharf superstructure. Current research focuses on the case where the forward direction of the wave is perpendicular to or inclined to the wharf front line and mostly applied physics modelling experiments. This paper is to study the case where the wave is parallel to the front line of the high-pile wharf. Take a high-pile wharf near estuary as a model and use the finite element software Ansys to establish the space model. Analysis of internal forces and the destruction of high-pile wharf are made. Meanwhile, the preliminary solution depending on the destruction are proposed, providing references for projects.

Abstract: Wave force is one of the most important environmental disturbing forces in ship motion mathematical model. Calculating the wave force in ship mathematical model is of a great importance about prediction of ships maneuverability. In order to calculate the longitudinal wave force in MMG ship motion mathematical model, the CFD method was used in this work to build numerical wave flume. The 3D model of M/V YUKUN and hexahedral mesh of the domain of the flow field were made. Software Fluent was used to simulate the motion of YUKUN in regular longitudinal waves, and the wave force acting on YUKUN was obtained. Finally, regression formula was built based on the simulation results.

Abstract: A three dimensional numerical model to calculate the wave forces on the composite bucket foundation of the offshore wind turbine is established and the analytical method to approximatively calculate wave forces on the structure with the variable cross section is proposed. Based on the validation of numerical results, wave forces on the composite bucket foundation are calculated under different wave conditions. The variable cross-section of the composite bucket foundation is divided into sections with the approximate same diameter. Comparison with the numerical calculations and analytical results, the wave force on each section can be calculated using Morison equation when the relative diameter is less than 0.2 and using diffraction theory when the relative diameter is more than 0.2.

Abstract: During the process of exiting from water, the unpowered carrier launched by submarine will be disturbed by the wave force. It will have impact on the trajectory of carrier. Based on carrier vehicle exiting water requirement the six degrees of freedom mathematical model of carrier was established. The calculation model for wave force was built based on the two dimensions wave theory. The steering sequence of carrier was designed and the process of the carrier out of water was simulated under the influence of wave force. The results show that the vehicle movement stability, the control law is reasonable and the simulation methods and results of engineering research had a certain reference value.

Abstract: Platform structure is the basic guarantee for safety operation of offshore wind turbine. Based on the boundary element method and combined with multi-body dynamics, analyzing motion response and wave force mechanism to the platform structure, and obtained the dynamic response and the wave force change of the platform structures in time domain, last analyzes the motion response and wave force change of tension leg platform in surge, sway and heave also roll, pitch and yaw direction. The results show that the maximum response of sway and the minimum response of surge have the same direction, it is the same with the maximum response of pitch and the minimum response of roll ; Motion responses of heave and yaw change not as acutely as other four directions ; In time-domain variation range, motion response of surge, heave and pitch change acutely, while motion responses of sway, roll and yaw change slightly. Wave force focus mostly in heave and pitch direction. The results is high reference value on offshore tension leg platform structural design and optimization.

Abstract: In order to study the wave force acting on the hollow blocks structures locating at the permeable foundation under the regular wave flume, the wave tank is established basing on improved N-S Equations. And the moving boundary’s generating wave and wave absorption of momentum source are adopted in the numerical wave flume. It can also be simulated permeable foundation by porous media module. Then mathematical model can be constructed under the interaction between waves and hollow block when PISO is used to couple velocity and pressure fields. At the same time, the numerically calculated results of the wave force acting on the hollow blocks are compared with the experimental data in agreement. In conclusion, the variation of the wave force with incident wave height and period is obtained through the numerical calculation.

Abstract: The grouping pile foundation is widely used in the construction of bridge over sea and its scale of construction is generally dominated by the wave force on the pile groups. Because of the presence of the slab, not only the incident wave but also the diffraction wave should be considered in calculating wave loads on pile groups. The diffraction from a submerged circular cylinder representing the slab was taken as an example, and wave loads on piles in the diffraction wave field were calculated by using Morison formula. Results show that the effect of slab decreases with the increase of incident wave number. Changing laws of different piles in the pile-group foundation varied with the submerged depth. Wave loads at the meeting-wave side of slab is larger than the back side of that. And the presence of slab caused the deflexion of inline force. The grouping piles coefficient can be taken as 0.7.

Abstract: In order to design a double buoys mooring system in the estuary of Yalu River for loading work of 40,000 tons of bulk cargo ship, the article mainly based on the practicality of the meteorological condition of this sea area and the data of the vessel as well as the national criterion, do some calculations of wind force, current force, wave force as well as the total force on the ship, with the calculation result to make a designation of double mooring buoy system, decide the size of the mooring buoy, the size and length of the chain, the size and the depth of the Deadman. The construction according to the designation has a good effect; the method of calculation and the designation are proved useful.