An Efficient Numerical Method for Higher Order Springing Induced Loads

本项目的目的是进一步发展一种基于朗肯源的三维边界元方法，以预测波浪中作用于船体结构上的截面载荷，并考虑弹簧诱导的水弹性效应。引起船舶共振响应的波浪诱导力又细分为弗劳德-克雷洛夫力、辐射力和绕射力。对于高阶弹性，重要的是要考虑与弗劳德-克雷洛夫力有关的非线性效应。这些力是基于瞬时湿表面在每个时间步长中计算的。关于弹簧，绕射力和辐射力可以用线性方法来处理。它们在频域中计算，并使用卷积积分在时间域中传输。为了考虑水弹性效应，流动方程与运动方程(刚性和弹性)相耦合。弹性变形的计算使用了一种模式分解方法，以有效地求解一组简化的固有模式。将使用Vlasov梁和三维有限元模型。此外，还将开发和验证流体动力阻尼器的简化预测方法。模型试验和基于雷诺平均的纳维斯托克斯方程的现场方法的结果广泛地验证了将要开发的方法。

The aim of this project is to further develop a three dimensional boundary element method based on Rankine sources to predict sectional loads acting on ship structures in waves taking into account springing induced hydroelasticity effects. Wave induced forces leading to resonant ship responses are subdivided into Froude-Krylov, radiation and diffraction forces. For higher order springing it is important to consider nonlinear effects related to Froude-Krylov forces. These forces are computed in each time step based on the instantaneous wetted surface. With regard to springing diffraction and radiation forces can be treated in a linear way. They are computed in the frequency domain and transferred in the time domain using convolution integrals. To account for hydroelasticity effects the flow equations are coupled with the equations of motion (rigid and elastic). The elastic deformations are computed using a modal decomposition approach to efficiently solve a reduced set of natural modes. A Vlasov beam and three dimensional Finite-Element models will be used. Further, simplified methods for prediction of hydrodynamic damping will be developed and verified. The methods to be developed are extensively validated using results from model tests and field methods based on Reynolds-Averaged-Navier-Stokes-Equations.