孤立波与板式结构物相互作用的数值模拟

发布时间：2018-05-14 14:39

本文选题：孤立波 + 板式结构　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：海洋工程结构物在大幅波浪环境中通常会遭遇非常复杂的强非线性水动力现象,对这一过程涉及的物理机理和流场特性的研究是波浪与结构物相互作用问题的关键难点。理论解析对强非线性问题已极难实现,而模型实验又受限于高昂的成本和尺度效应,基于粘性流理论的CFD方法因此被认为更擅长于极端波浪对结构物冲击问题的求解。海洋工程设施中通常含有大量的板式结构,大幅波浪条件下板式结构的破坏机理和流场分布特征目前尚未得到完整的阐释。首先,本文通过求解粘性流N-S方程,在正交笛卡尔坐标系上建立了可处理强非线性问题的多相流数值模型。当前流场求解器采用具有三阶时空精度的CIP(Constrained Interpolation Profile)方法离散求解对流项;采用中心差分法数值处理扩散项;采用超松弛迭代法计算压力Poisson方程。对于多相流模型中的界面处理,选择高精度THINC(Hyperbola for Interface Capturing)法捕捉自由面,使用虚拟粒子法精确重构固体的几何形状。通过数值模拟正弦波和孤立波的生成与传播,验证了本模型具有良好的时空收敛性、数值稳定性和造波性能。之后,基于上述建立的多相流模型,研究了孤立波与板式结构物的相互作用问题,包括固定的水平板结构和垂向板结构。对于孤立波对水平板的砰击作用,重点研究了结构物上的波浪载荷分布特性。通过与现有实验数据和其他数值结果进行对比,验证了当前数值模型的水动力预报性能,并进一步讨论分析了越浪、波浪破碎等现象对结构物波浪载荷分布的影响。孤立波对垂向板结构冲击过程的数值研究则重点关注模型的自由面运动和流场分布特征。根据已有的模型实验,对当前模型模拟精细流场特征和计算强非线性自由面运动的可靠性和精度进行验证与说明。此外还深入研究了结构物的几何参数对自由面运动和波浪传播特性的影响,以及速度域和压力场等流场特征的分布与变化规律。本研究对孤立波与板式结构物相互作用问题开展了充分的数值验证工作和详细的物理机理分析。当前研究结果表明本文建立的数值模型可以比较理想地处理孤立波对板式结构的冲击问题,数值结果与实验数据对于大多数算例比较吻合,数值模拟可以比较精确地反映实际流场的自由面运动和分布特征,数值模型可以为板式结构物提供定量、可靠的水动力预报。本文通过对当前数值模拟和计算结果的讨论分析得到的相关结论对于海洋工程结构物的设计与建造具有一定的参考价值和指导意义。
[Abstract]:Marine engineering structures usually encounter very complex nonlinear hydrodynamic phenomena in large wave environments. The study of the physical mechanism and current field characteristics involved in this process is a key difficulty in the interaction between waves and structures. Theoretical analysis is very difficult to solve strongly nonlinear problems, and model experiments are limited by high cost and scale effect. Therefore, the CFD method based on viscous flow theory is considered to be better at solving extreme wave impact problems on structures. Offshore engineering facilities usually contain a large number of plate structures. At present, the failure mechanism and current distribution characteristics of plate structures under large wave conditions have not been fully explained. Firstly, by solving the N-S equation of viscous flow, a numerical model of multiphase flow is established in orthogonal Cartesian coordinate system to deal with strongly nonlinear problems. The current flow field solver uses the CIP(Constrained Interpolation profile method with third-order space-time accuracy to solve the convection term discretely; the central difference method is used to numerically process the diffusion term; and the overrelaxation iterative method is used to calculate the pressure Poisson equation. For the interface processing in the multiphase flow model, the high precision THINC(Hyperbola for Interface Capturing) method is chosen to capture the free surface and the virtual particle method is used to accurately reconstruct the geometry of the solid. The generation and propagation of sinusoidal and solitary waves are numerically simulated, and it is proved that the model has good spatiotemporal convergence, numerical stability and wave-making performance. Then, based on the multiphase flow model, the interaction between solitary wave and plate structure is studied, including the fixed horizontal plate structure and vertical plate structure. For the slamming effect of solitary waves on horizontal plates, the distribution of wave loads on structures is studied. By comparing with the existing experimental data and other numerical results, the hydrodynamic prediction performance of the current numerical model is verified, and the effects of wave surges and wave breakage on the wave load distribution of structures are discussed and analyzed. The numerical study of the impact process of solitary waves on vertical plate structures focuses on the free surface motion and flow field distribution of the model. According to the existing model experiments, the reliability and accuracy of simulating the fine flow field and calculating the strong nonlinear free surface motion of the current model are verified and explained. In addition, the effects of geometric parameters of structures on the characteristics of free surface motion and wave propagation, as well as the distribution and variation of flow field characteristics such as velocity domain and pressure field, are also studied. In this study, numerical verification and detailed analysis of the physical mechanism of the interaction between solitary waves and plate structures have been carried out. The present research results show that the numerical model established in this paper can deal with the impact of solitary wave on plate structure perfectly, and the numerical results are in good agreement with the experimental data for most examples. The numerical simulation can accurately reflect the free surface motion and distribution characteristics of the actual flow field, and the numerical model can provide quantitative and reliable hydrodynamic prediction for plate structures. The conclusions obtained in this paper through the discussion and analysis of the current numerical simulation and calculation results have certain reference value and guiding significance for the design and construction of marine engineering structures.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U661.1;P75

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