Numerical Simulations Of Viscous Flow Around The Ship Maneuvering In Restricted Waters

In recent years,the size of modern ships has increased rapidly along with the new techniques and knowledge available.Although the dimensions of modern ships,especially draft and width,have become larger and larger,the infrastructure needed for ship operation has not kept pace at the same rate.As a consequence,near-coast waters as well as inland waterway,et al,are becoming restricted waters,as the waters there are becoming shallower and narrower relatively.The shallow water and narrow channel in restricted waters will influence the flow field around the ship and then change the ship behavior.As a result,ship performance in restricted waters is much different from that in open waters and ship manoeuvring in restricted waters is also more difficult.Therefore,investigating ship behavior in restricted waters is of great significance for ensuring the ship safety in these waters.The objective of this dissertation is to study the viscous flow around the ship maneuvering in restricted waters,by taking into account the fluid viscosity and free surface effects.All the work is carried out with the help of our in-house code and the overset grid technique.(1)Numerical study of the viscous flow and the hydrodynamic forces on a obliquely towed KVLCC2 M ship model in shallow water.The viscous flow around an obliquely towed KVLCC2 M ship model in both deep and shallow water is investigated by adopting the static overset grid method.The hydrodynamic performance of the obliquely towed KVLCC2 M ship model in deep water,the pressure distribution on the ship surface as well as the wake field are studied firstly and compared with experimental data,the reliability of the code and the numerical methods are verified by the good agreement of the computational results and experimental data.Then,the influence of the water depth and drift angle on the ship hydrodynamic performance is investigated.The pressure distribution on the ship surface is analyzed together with the wake field to explain the characteristics of performance of the obliquely towed ship.(2)Numerical investigation of the viscous flow and the hydrodynamic forces on a KVLCC2 ship model in pure sway maneuvers in shallow water.The viscous flow around the KVLCC2 ship model in different water depth is investigated numerically by applying the dynamic overset grid method.The reliability of the code and the numerical methods,as well as the advantage of overset grid technique are further verified by the good agreement of the computational results and experimental data.(3)Numerical study of the viscous flow around a 12000 TEU ship model manoeuvring in locks.The rationality and reliability of the use of the code and the numerical methods in the prediction of the ship behavior in lock are firstly proved by the good agreement of the computational results and experimental data.Then,the effects of the ship speed,water depth,as well as the eccentricity on the ship performance when passing through the lock are studied numerically.The ship surface pressure distribution,wave height of the free surface and the wave field are analyzed to explain the ship hydrodynamic performance.The behavior of the ship passing through the GOUPITAN ship lift with different speeds is also studied numerically.Besides,the wave height at the gauge,ship surface pressure distribution,as well as the wake field,are analyzed to further explain the ship performance.(4)Numerical prediction of ship-ship interaction during a lightering operation in shallow water.Numerical study of the KVLCC2-Aframax interaction during a lightering operation is presented.At the first stage,the rationality and reliability of the use of the code and the numerical methods in the prediction of the ship-ship interaction are confirmed by the good agreement of the computational results and experimental data.The influence of the longitudinal distance,lateral positions and water depth is then studied and the characteristics of the ship hydrodynamic performance are explained by analyzing the wave pattern,ship surface pressure distribution,as well as wake field.With the help of the overset grid technique,the viscous flow field and ship performance in restricted waters are studied numerically by solving URANS equations.The free surface effects are taken into account to obtain more detailed flow field information.The ship hydrodynamic performance is explained by the analysis of the flow filed.The results are theoretically significant and practically useful for the investigation of the ship behavior in restricted waters.