Numerical Simulation Of Ship Waves And Their Run-up In Inland River Channel

Researchers all over the world have studied research on ship waves.In the past 250 years,much effort has been done to predict ship's hull resistance,eliminate wake,and control the dynamic performance of ships in waves.Recently,with the development of inland river channel,the ship density becomes higher than ever before.Bank erosion and negative influence on floating bodies caused by ship waves attract special attention of the public.Although there exist a number of empirical formulas,which could be used to evaluate the magnitude wave height and run-up of ship waves on bank slope,they cannot be used directly because of different hypothesis that these formulas are based on.In order to research into the generation,propagation and reflection of ship waves,a CFD software is employed to develop a numerical simulation method of ship waves in a navigational channel.Based on the hypothesis that the water is incompressible and viscous,the PDEs used here are the continuity equation,RANS equations,VOF equation and RNG k-? turbulence equations.The software discretizes PDEs with finite difference method in Cartesian coordinate system.The numerical model should be validated so as to precisely simulate ship waves in restricted waters.In this thesis,the validation was divided into two parts.The first part is to compute the ship waves generated by DTMB5415 ship hull.Given a uniform incoming flow,the resistance of the hull is predicted numerically.The numerical results of the water elevation on different slices along the hull are obtained and discussed.The second part is the numerical simulation of a commercial ship running in a channel based on the field information from the Le Ma River in Shanghai,China.The computed run-up and run-down of the ship waves on the typical section are compared with the measured data.The validation results show that the numerical model can be used to simulate ship waves accurately.The process of generation,propagation,reflection and run-up can also be simulated numerically.Moreover,the mesh used in validation simulations can be transferred to other simulations.The characteristic height and run-up of ship waves can easily be affected by many factors which can be divided into environmental factors and ship factors.The environmental factors consist of flow condition,channel depth and width,slope angles et al.,while the ship factors consist of navigating speed over water,ship draft,and streamline of hull beneath water.Among these influential factors,sailing speed over water,ship draft,channel depth and bank slope should be accused to determine wave height and run-up/-down.The results from a series of simulations reveal the characteristics of the surface elevation and flow field in water constrained by vertical wall or slope bank.The maximum run-up and run-down of ship waves are obtained.Influence of sailing speed over water,ship draft and slope angle on the maximum run-up and run-down of ship waves are discussed.Several primary empirical formulas are proposed to calculate wave height and run-up/-down of ship waves in a channel.