Characteristics of Turbulent Boundary Layr with 3-dimensional Separation

研究了有纵向旋涡时的湍流特性和由于旋涡的存在而引起的边界层变形，得到了以下结果：1.对精细船模(Series 60，Cb=0.6)和全船型(Ryuko-Maru)的三维湍流流动特性进行了实验研究。结果表明：(1)获得了准确的三维平均速度分量、旋涡和雷诺应力分布的数据库；(2)纵向旋涡峰值位置与雷诺应力峰值位置不对应，纵向旋涡内部湍流强度较弱；(3)尾迹分布受尾部附近三维分离引起的旋涡变形；(4)纵向旋涡内部速度与旋涡外部区域的脉动相位不同。(5)用Boussinesq假设估算的法向应力分量与实验结果吻合较好，但剪应力分量不一致。(6)基于Boussinesq假设的湍流模型低估了剪应力，而以螺旋度为基础的运动涡粘性阻尼法低估了剪应力。进行了CFD计算，计算结果与实验结果定性一致，即计算了尾迹的弱变形分布。利用图像处理技术测量了船体表面的剪应力分量。在自由表面切向应力为零的条件下，计算了弓波破裂。

Characteristics of the turbulence with longitudinal vortices and deformation of boundary layr, due to the existence of the vortices are investigated.Obtained results are as follows ;1. Characteristic of 3-dimensional turbulent flow around a fine ship model (Series 60, CB=0.6) and a full ship form (Ryuko-Maru) were investigated experimentally. The results are,(1) Accurate data-base for 3-D averaged velocity components, vortices and Reynolds stress distributions are obtained.(2) Position of the peak value of longitudinal vortices are not correspond to the peak of Reynolds stress and turbulence strength are weak inside of the longitudinal vortices.(3) Wake distribution is deformed by vortices which was caused by 3-D separation near the stern bilge.(4) Phase of fluctuation between the velocity inside of the longitudinal vortices and the outer region of the vortices are differ each other. Strong correlation between the fluctuations of the area of longitudinal vortices and fluctuations of x-component of velocity are recognized.(5) Estimated normal stress components using Boussinesq's hypothesis are well coincident with experimental results but shear stress components are not coincident.(6) Turbulence model based on the Boussinesq's hypothesis underestimate the shearing stress and the damping method for the kinematic eddy viscosity by helicity underestimate more the shearing stresses.2. CFD calculations are carried out and the results show qualitative agreement with experimental results, i.e.weak deformation of the wake distribution is calculated.3. Shearing stress components on the hull surface are measured by image processing technique.4. Bow wave breaking are calculated with the zero tangential stress conditions on the free surface.