数值计算

A new method for the generation of curvilinear grid has been proposed. Some curvilinear grid generation examples show that satisfactory grids can be generated for simple-connected regions and connected- regions with complex boundary by using the proposed adjusting factors.

3提出了一种生成边界处正交曲线网格的新方法，收敛速度快，在复杂边界流场区域的数值计算中，有很大的实用价值；为了克服复杂几何边界给数值计算带来的困难，提高通用性以及水流的预测精度，本文采用上述网格生成技术，在直角坐标系三维非恒定明渠紊流的沿层积分数值模型基础上，发展了曲线坐标系下的多层紊流水动力模型。

Then the FLUENT software was used to simulate the amphibious vehicle' ambient flow field through defining the unsteady boundary condition. The lift, resistance, velocity, pressure, and wave of the amphibious vehicle moving in the regular waves were obtained, which can avoid the errors resulted from neglecting the free surface and provides theoretic basis for the research on optimization design of high performance amphibious vehicle.

在计算出某改进型两栖车在微幅规则波中高速迎浪运动时升沉和纵摇特性的基础上，运用FLUENT软件，通过自定义非定常入口边界实现了两栖车在微幅规则波中运动的三维流场数值模拟，得到了升力、阻力、速度、压强和兴波等流场参数，实现了两栖车在波浪中的绕流场数值模拟，解决了以往由于忽略兴波特性导致数值计算结果随航速提高误差不断增大的问题，为高性能两栖车的外形设计研究提供了理论依据。

In the numericalstudy, three-dimensional elastodynamics equations and Morison equation are applied tosimulate the time histories of dynamic response of submarine pipelines suspended over flatbeds sucessfully. The three-dimensional interaction of pipeline and internal flow isnumerically simulated by applying the iterative computation to the fluid-structure interfacesand using the elastodynamic equation and the incompressible fluid N-S equation andcontinuity equation.

在数值研究方面，本文利用三维弹性动力学方程，结合莫里森方程，较好地模拟了规则波浪作用下近壁悬跨弹性海底管线动力响应过程，结合不可压缩流体N-S方程和连续方程，进行管线及其内部流体的三维流固耦合数值计算，基于数值计算结果探讨内流管线系统的动力特性和管内流体特征。

Through adopting frequency-response functions and railway track irregularity PSD, methods and models are optimized. The speed of simulation is enhanced with fast Fourier transformation.

通过引入频响函数及轨道不平顺谱优化了列车荷载数值算法及计算模型，并在数值计算中采用傅里叶快速数值算法，提高列车荷载的模拟的效率和可靠性。

Second order incident boundary condition on fixed incident boundary is derived for numerical simulations, based on the cnoidal or sinusoidal motions of wave maker paddle, which shows that the prediction with second order incident boundary condition is more accurate than the prediction with first order incident boundary condition. 2 The analytical solution for higher-order Boussinesq equations is derived and its applicable range is discussed. 3 A 2-D fully non-linear numerical model using boundary element method is developed to obtain wave forces acting on rectangular obstacle. 4 The three-dimensional fully non-linear waves are studied in a numerical wave tank using finite element method.The studies on the coupled numerical model combined Boussinesq equations with Laplace equation are following.

非耦合非线性波浪计算模型：1 根据造波板做椭圆余弦运动或正弦运动速度，推导出数值模拟波浪水槽时固定入射边界上的二阶波浪入射边界条件，数值计算结果和实验结果的对比表明采用二阶入射边界条件对波面升高的预报比采用一阶入射边界条件对波面升高的预报更为精确；2 推导了波浪水槽造波板做正弦运动所产生波浪的高阶Boussinesq方程摄动展开解析解，讨论了该解析解的适用范围；3 对整个波浪水槽应用边界元方法数值模拟了波浪对物体的非线性作用；4 用有限元法求解三维Laplace方程模拟了三维完全非线性波浪水槽。

This paper brief introduce numerical method of algebraic equation,points out their shortcoming of missing multiple root and put forward one new kind of method--multiple derivation numerical method.

本文对通常代数方程的数值计算方法特点进行了简介并给以分析，指出了这些解法无法得出重根数的缺陷，提出了一种新的解决方法———多次求导数值计算法，使得数值计算法更加清晰、明了，且可得出重根数。

Therefore, it is necessary to test the computation results and further modify the computation method based on the comparison between the numerical solution of the linear or non-linear equations and the trial value or the computation results of typical cases.

所以，需依靠对非线性数学方程的数值实验及数值解与试验或典型算例结果的比较和物理特性分析，验证数值计算结果，进一步改进计算方法。

The new singular element at the end of a blunt crack is obtained,the new method for calculating stress intensity factors of blunt crack problems is presented.

利用其局部解构造了一种新的大曲率缺口位移模式；建立含大曲率缺口损伤结构有限元方程和与相应的缺口奇异单元；提出了求解大曲率缺口应力与应力强度因子等断裂参量的数值计算方法，数值算例说明本文方法是一种有效的数值计算分析方法。

The symplectic schemes have the ability to preserve the global symplectic structure of the phase space for a Hamiltonian system. They have substantial benefits in numerical computation for Hamiltonian system, especially in long-term simulations.

辛算法正是保持Hamilton系统内在性质的一种新型数值方法，该算法在长时间的数值计算中，具有常见数值方法无可比拟的计算优势。

The comparison of the computational results of real gas model with that of perfect gas model shows that it is very important to apply the real gas model in the numerical simulations, and also the real gas model presented shows itself more profitable and applicable in numerical applications.

对单列叶栅和透平级内复杂三维凝结流动的数值计算方法进行了研究，结合欧拉/欧拉型自发凝结数值模型，以FLUENT软件N-S求解器为平台，建立了适合工程实际应用和复杂条件下非平衡凝结流动的数值计算系统。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。