船舶多自由度斜航运动水动力数值研究（英文）

Numerical Study on Hydrodynamics of Ships in Oblique Motion with Multi-Degree of Freedom

计及多自由度运动的船舶斜航水动力预报对船舶航行安全具有重要意义。文章通过耦合求解船舶运动方程和雷诺平均N-S方程,并采用VOF方法和高精度自由面捕捉技术对作多自由度斜航运动船舶的粘性绕流场进行数值模拟。船舶动态平衡位置根据计算出的力和力矩来决定,得到包括升沉、纵倾和横倾在内的船舶浮态。文中采用的算例与爱荷华大学进行的模型试验相同,通过比较数值计算结果和试验值验证了该方法的有效性。对船模在受约束和自由运动两种状态下的船舶运动和流场进行模拟,通过比较分析船舶升沉、纵倾和横倾的影响。文中计算获得的详细流场细节特征,包括前体和舭部的涡以及船体表面上的压力,有助于理解船舶斜航运动浮态变化的机理。

It is of significance for the safety of ship to predict the hydrodynamic forces on ship in oblique motion with multi-degree of freedom. In this work, the free-surface viscous flow around ship in oblique motion with multi-degree of freedom is simulated by coupling the equations of ship motion with the Reynolds Averaged Navier-Stokes （RANS） equations. The free surface is modeled by using Volume-of-Fluid （VOF） approach and a high-resolution interface-capturing scheme. The calculated forces and moments are used to determine the dynamic equilibrium position of the ship at the specified speed. Hereby, the running attitudes including the sinkage, trim and heel are obtained.The computations presented here are an effort to numerically simulate the cases as the same as the experiments reported by IWOA （The University of Iowa）, and validation of the present method is verified by comparing the present numerical results and measurements. Two sets of simulations are performed, including the model-fixed condition and the model-free condition. Comparisons between the model-fixed condition and model-free condition can enable the identification of the sinkage-, trim- and heel-induced effects. The detailed flow field characteristics including the forebody vortex, bilge vortex, pressure distribution on the hull surface are obtained, which are helpful to understand the mechanism causing the change of running attitude in ship＇s oblique motion.