开发了一种基于B样条的高阶面元法用来求解浅水船舶兴波问题。船体表面和自由面上分别布置Rankine源,同时利用镜像原理来计及水底的影响。物体几何用 B 样条曲面精确表示。在求得边界面上的源强密度分布后,物面上的速度势用B样条来表示。数值计算中采用配置方法,并且用高斯—勒让德公式来计算方程中的积分。为了验证文中方法的有效性,用本方法计算了Wigley船在深水和浅水中的兴波水动力和波形,所得数值结果与试验结果和其它数值结果进行了比较,吻合程度令人满意,表明本方法被用来求解浅水船舶兴波问题是有效的。
A desingularized high order panel method based on Non-Uniform Rational B-Spline (NURBS) was developed to deal with three-dimensional potential flow problems. A NURBS surface was used to precisely represent the body geometry. Velocity potential on the body surface was described by the B-spline after the source density distribution on the body surface had been solved. The collocation approach was employed to satisfy the Neumann boundary condition and Gaussian quadrature points were chosen as both the collocation points and the source points. The singularity was removed by a combined method, so the process of the numerical computation was non-singular. In order to verify the method proposed, the unbounded flow problems of sphere and ellipsoid, the wave-making problem of a submerged ellipsoid were chosen as computational examples. It is shown that the numerical results are in good agreement with analytical solutions and other numerical results in all cases, and sufficient accuracy of numerical solution can be reached with a small number of panels.
In order to generate the three-dimensional (3-D) hull surface accurately and smoothly,a mixed method which is made up of non-uniform B-spline together with an iterative procedure was developed.By using the iterative method the data points on each section curve are calculated and the generalized waterlines and transverse section curves are determined.Then using the non-uniform B-spline expression,the control vertex net of the hull is calculated based on the generalized waterlines and section curves.A ship with tunnel stern was taken as test case.The numerical results prove that the proposed approach for geometry modeling of 3-D ship hull surface is accurate and effective.
The viscous hydrodynamic force and moment on ships moving obliquely in shallow water are important for ship navigation safety.In the paper,the viscous flow field around a KVLCC2 model moving obliquely in shallow water is simulated and the hydrodynamic drag,lateral force and yaw moment acting on the hull are obtained by a general purpose computational fluid dynamics(CFD) package FLUENT with shear-stress transport(SST) k—ωturbulence model.The numerical computation is performed at different drift angels and water depths.The numerical results are compared with experimental results,and a good agreement is demonstrated.
