Application of the VOF method based on unstructured quadrilateral mesh

To simulate two-dimensional free-surface flows with complex boundaries directly and accurately, a novel VOF (Volume-of-fluid) method based on unstructured quadrilateral mesh is presented. Without introducing any complicated boundary treatment or artificial diffusion, this method treated curved boundaries directly by utilizing the inherent merit of unstructured mesh in fitting curves. The PLIC (Piecewise Linear Interface Calculation) method was adopted to obtain a second-order accurate linearized reconstruction approximation and the MLER (Modified Lagrangian-Eulerian Re-map) method was introduced to advect fluid volumes on unstructured mesh. Moreover, an analytical relation for the interface’s line constant vs. the volume clipped by the interface was developed so as to improve the method’s efficiency. To validate this method, a comprehensive series of large straining advection tests were performed. Numerical results provide convincing evidences for the method’s high volume conservative accuracy and second-order shape error convergence rate. Also, a dramatic improvement on computational accuracy over its unstructured triangular mesh counterpart is checked.     

桥面板干湿混合接缝在组合梁斜拉桥中的应用研究

为提高组合梁斜拉桥混凝土桥面板横向预应力的施加效率,减少桥面板的纵向裂缝,提出一种可在混凝土桥面板与钢横梁结合前施加横向预应力的干湿混合接缝新型桥面构造。以鳌江特大桥为工程背景,采用通用有限元软件ANSYS建立局部有限元模型,计算比较传统湿接缝桥面板和新型干湿混合接缝桥面板的预应力施加效率。在鳌江特大桥上设置试验段应用干湿混合接缝新型桥面构造,现场测试施工阶段混凝土桥面板应力变化情况。结果表明:组合梁斜拉桥采用干湿混合接缝的新型桥面构造,可实现在混凝土桥面板与钢横梁结合前施加横向预应力,横向预应力施加效率提高了约70%,可减少混凝土桥面板纵向开裂;实桥测试中干湿混合接缝桥面板纵横向应力满足规范要求。     

旋转壳体的干,湿模态研究

本文用振动试验建模的方法来探索旋转壳体的干、湿模态参数及其非线性振动特性。还分析了附连水质量与水域大小的关系以及附连水质量对振动特性变化的影响。     

用耦合法分析道床的弹塑性应力

本文采用有限元与边界元耦合方法分析了道床应力，其中对发生弹塑性变形的道床结构采用有限元法，对半无限域的地基采用边界元法。由于有限元法在进行非线性分析时具有效率高，而边界元法在横拟半无限域时具有计算简单的特点．因此该方法集中了有限元与边界元的优点．计算精度和计算效率较一般数值方法明显提高。     

无限边界元及其在岩土工程中的应用

本文采用无限边界元法对无限或半无限域作弹性分析。给出了无限边界元法的位移和面力插值函数,这些插值函数中含有衰减函数。由此建立了相应的计算列式。数值算例显示,本方法是有效的并能大幅度节省机时,它在岩土工程中具有应用前景。     

混合边界薄板的弯曲问题

综合应用差分法和配点法，研究了混合边界矩形薄板的弯曲问题。文末给出的算例结果与文［1］、［3］的结果十分接近，由此说明了本文方法的有效性。     

船波边界积分法中的自由表面奇点上置

利用由Ｆｏｕｒｉｅｒ分析得到以公式及相应的数值计算，对船波问题的边界积分方法中自由表面奇点上置的影响进行了讨论，认为奇点上置位置的适当选取将有助于改善数值计算中的色散误差并降低其对于网格变化的敏感程度。