An Efficient Numerical Method for Higher Order Springing Induced Loads

本项目的目的是进一步发展基于朗肯源的三维边界元方法，以预测波浪中考虑弹簧诱导水弹性效应的船舶结构的截面载荷。引起船舶共振响应的波浪诱导力可细分为弗劳德-克雷洛夫力、辐射力和衍射力。对于高阶弹簧，考虑与弗劳德-克雷洛夫力有关的非线性效应是很重要的。这些力是基于瞬时湿表面在每个时间步中计算的。关于弹簧衍射和辐射力可以用线性的方式来处理。它们在频域中计算，并在时域中使用卷积积分进行传递。为了考虑水弹性效应，流动方程与运动方程（刚性和弹性）耦合在一起。采用模态分解方法计算弹性变形，有效地求解简化的自然模态集。将使用弗拉索夫梁和三维有限元模型。此外，还将开发和验证水动力阻尼预测的简化方法。采用基于reynolds - average - navier - stokes方程的模型试验和现场方法对待开发的方法进行了广泛验证。

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.