有限元网格自动生成及绘制中的实用处理技巧

提出了超大单元、结点归一化相对距离判别法这一快速三维自动剖分技术，针对大型水工建筑物的特点，给出了几种常遇问题的实用处理方法；还给出了适合工程实际的超大面判断立体消隐图绘制法和基于Ａｕｔｏｌｉｓｐ语言及Ａｕｔｏ－ＣＡＤ的立体图处理方法．     

无单元法在有自由面渗流计算中的应用

针对有自由面渗流分析中的有限元固定网各法存在的不足，利用无单元法中积分网格和结点相互独立的优点，提出了有自由面渗流的无单元法。计算结果表明，无单元法可以方便地解决迭代计算中的自由面变化问题，实现了真正意义上的网格固定。     

改进的小损伤结构动力学有限元建模方法

在遗传算法或神经网络方法识别结构损伤位置和程度时,都是基于少量的在线测量的损伤结构振动响应数据和大量的模型仿真数据来实现的,因而建立高效和精确的损伤结构动力学有限元模型,以便仿真获得损伤结构的大量动力学响应数据是十分重要的基础前提工作。本文针对ANSYS结构分析软件在建立结构小损伤有限元动力学模型存在两个关键问题,结构损伤处直接网格划分的计算结果误差和网格节省问题,以结构损伤振动检测的实际需要为出发点,提出了建立含小损伤结构的ANSYS动力学建模技术,研究了结构局部小损伤及其位置与所在处单元刚度矩阵变化的数量关系。     

复杂无粘流场数值模拟的矩形/三角形混合网格技术

建立了一套模拟复杂无粘流场的矩形／三角形混合网格技术，其中三角形仅限于物面附近，发挥非结构网格的几何灵活性，以少量的网格模拟复杂外型；同时在以外的区域采用矩形结构网格，发挥矩形网格计算简单快速的优势，有效地克服全非结构网格计算方法需要较大内存量和较长ＣＰＵ时间的不足．混合网格系统由修正的四分树方法生成．将ＮＮＤ有限差分与ＮＮＤ有限体积格式有机地融合于混合网格计算，消除了全矩形网格模拟曲边界的台阶效应，同时保证了网格间的通量守恒．数值实验表明本方法在模拟复杂无粘流场方面的灵活性和高效性．     

自适应网格加密和多重网格求解严重病态方程

本文探讨用自适应网格加密技术结合多重网格法求解由有限元离散导致的病态方程。计算结果表明；自适应多重网格有限元法是求解严重病态方程珠有效方法。     

Experimental investigation on tunnel sonic boom

Upon the entrance of a high-speed train into a relatively long train tunnel, compression waves are generated in front of the train. These compression waves subsequently coalesce into a weak shock wave so that a unpleasant sonic boom is emitted from the tunnel exit. In order to investigate the generation of the weak shock wave in train tunnels and the emission of the resulting sonic boom from the train tunnel exit and to search for methods for the reduction of these sonic booms, a 1300 scaled train tunnel simulator was constructed and simulation experiments were carried out using this facility.In the train tunnel simulator, an 18 mm dia. and 200 mm long plastic piston moves along a 40 mm dia. and 25 m long test section with speed ranging from 60 to 100 m/s. The tunnel simulator was tilted 8° to the floor so that the attenuation of the piston speed was not more than 10 % of its entrance speed. Pressure measurements along the tunnel simulator and holographic interferometric optical flow visualization of weak shock waves in the tunnel simulator clearly showed that compression waves, with propagation, coalesced into a weak shock wave. Although, for reduction of the sonic boom in prototype train tunnels, the installation of a hood at the entrance of the tunnels was known to be useful for their suppression, this effect was confirmed in the present experiment and found to be effective particularly for low piston speeds. The installation of a partially perforated wall at the exit of the tunnel simulator was found to smear pressure gradients at the shock. This effect is significant for higher piston speeds. Throughout the series of train tunnel simulator experiments, the combination of both the entrance hood and the perforated wall significantly reduces shock overpressures for piston speeds ofu _p ranging from 60 to 100 m/s. These experimental findings were then applied to a real train tunnel and good agreement was obtained between the tunnel simulator result and the real tunnel measurements.     

轴对称高速碰撞问题的拉格朗日无结构网格有限体积法的并行计算

给出计算轴对称高速碰撞问题的拉格朗日无结构三角形网格有限体积法的并行格式，并给出以小巨型机ＡｌｉａｎｔＦＸ／４０为目标计算机的算例数值模拟结果和效率分析     

用有限元自适网格控制结构应力分析的精度

本文涉及有限元结构应务分析精度控制的三个基本方面：１）自适应的有限元网格自动生成技术；２）有限元应力分析的误差估计：３）用单元尺寸场将误差分布用于形成新网格。     

FV/MC混合算法求解轴对称钝体后湍流流场

介绍一种有限容积／Monte Carlo结合求解湍流流场的相容的混合算法．有限容积法求解Reynolds平均的动量方程和能量方程，Monte Carlo方法求解模化的脉动速度—频率—标量联合的PDF方程．将该算法发展到无结构网格，探讨了在无结构网格中实现两种方法的耦合，包括颗粒定位，颗粒场和平均场之间数据交换等问题．并以二维轴对称钝体后湍流流场作为算例，比较了计算结果与实验结果．