Simulation Analysis on Navigation Indexes of Wanzhou Yangtze River Highway Bridge after the Anti-Collision Device Construction by Ship Model Test

After the anti-collision facility construction of Wanzhou Yangtze River Highway Bridge, the conditions of navigation in bridge area are complex. In order to study the navigation conditions of the reach and layout optimization measures, ensuring the safety of the ship navigation test has been carried out on the ship model navigation in the bridge area. According to the requirements of the maximum safety limit of the ship model test, the paper puts forward the best route, the control method and the difficulty of navigation through the analysis of the test results, and finally gives the recommendations and suggestions.

Numerical Simulation on the Resistance Performance of Ice-Going Container Ship Under Brash Ice Conditions

Ice resistance prediction is a critical issue in the preliminary design of ships navigating brash ice conditions, which is closely related to the safety of a ship to navigate encounter brash ice, and has significant effects on the kinds of propellers and motor power needed. In research on this topic, model tests and full-scale tests on ships have thus far been the primary approaches. In recent years, the application of the finite element method(FEM) has also attracted interest. Some researchers have conducted numerical simulations on ship–ice interactions using the fluid–structure interaction(FSI) method. This study used this method to predict and analyze the resistance of an ice-going ship, and compared the results with those of model ship tests conducted in a towing tank with synthetic ice to discuss the feasibility of the FEM. A numerical simulation and experimental methods were used to predict the brash ice resistance of an ice-going container ship model in a condition with three concentrations of brash ice(60%, 80%, and 90%). A comparison of the results yielded satisfactory agreement between the numerical simulation and the experiments in terms of both observed phenomena and resistance values, indicating that the proposed numerical simulation has significant potential for use in related studies in the future.

NUMERICAL SIMULATION OF WAVE RESISTANCE OF TRIMARANS BY NONLINEAR WAVE MAKING THEORY WITH SINKING AND TRIM BEING TAKEN INTO ACCOUNT

Up to now, there are no satisfactory numerical methods for simulating wave resistance of trimarans, mainly due to the difficulty related with the strong nonlinear features of the piece hull wave making and their interference. This article proposes a numerical method for quick and effective calculation of wave resistance of trimarans to be used in engineering applications. Based on Wyatt＇s work, the nonlinear free surface boundary condition, the time domain concept, and the full nonlinear wave making theory, using the Rankine source Green function, the 3-D surface panel method is expanded to solve the trimaran wave making problems, with high order nonlinear factors being taken into account, such as the influence of the sinking and trim, transom, and ship wave immersed hull surface. And the software is successfully developed to implement the method, which is validated. Several trimaran models, including a practical trimaran with a sonar dome and the transom, are used as numerical calculation samples, their wave making resistance is calculated both by the present method and some other methods such as linear （Dawson） methods. Moreover, sample model resistance tests were carried out to provide data for comparison, validation and analysis. Through the validation by model experiments, it is concluded that present method can well predict the wave making resistance, sinking and trim, and the accuracy of wave making resistance calculation is significantly improved by taking the trim and sinking into account, especially at high speeds.

Study of Resistance Performance of Vessels with Notches by Experimental and Computational Fluid Dynamics Calculation Methods

Owing to the special working characteristics and operation requirements,lots of working ships have notches in different sizes and shapes in their hulls.In order to study the resistance performance of the vessel with notches,a series of model resistance tests were performed in respect to the 4 500 m 3 /h cutter suction dredger,and the tests were simulated based on the computational fluid dynamics software FLUENT.Based on analysis to the experimental data and the computational fluid dynamics(CFD) calculation results,the change of the flow field and the resistance performance caused by the notches were studied,and the reliability of the software in simulation of viscous flow around the hull was proved.It provides the basis for the future study and the design optimization of this kind of working ships.

Experimental Investigation into the Effect of Roll Amplitude on Roll Damping

An in-house large eddy simulation(LES)code has been developed in the previous study.In order to validate the code for simulation of roll motion,effect of roll amplitude on forced roll damping is experimentally investigated in a circulating water channel at Shanghai Jiao Tong University(SJTU).KRISO very large crude carrier 2(KVLCC2)is taken as a target ship,and a model with a scale of 1:128.77 is manufactured.Tests are carried out for the ship model at shallow draft with frequencies around its natural roll frequency,where natural roll frequency is attained via free roll decay.Six forced roll tests with roll amplitudes ranging from 1?to 4?are performed experimentally,and three forced roll motions are simulated with the in-house LES code for middle section of the ship model.Discrepancies between the computed roll damping coefficients and the ones from forced roll tests are quite small.By means of particle image velocimetry(PIV),velocity fields in the vicinity of the ship model,and generation and evolution of vortices near the ship bilge are measured in detail.It is shown that roll amplitude has a significant effect on the vortex behavior,and therefore on the magnitude of roll damping coefficient.Further experimental and numerical investigation into roll motions with large amplitudes is planned.