In order to verify the accuracy , credence and effectiveness of the unstructured overset grid algorithm , steady and unsteady flow field of naca0012 airfoil are simulated . the unsteady flow field is caused by the oscillation of the airfoil . the two computational results are both compatible well with the experimental data 为了验证非结构重叠网格方法的正确性、可靠性和有效性,本文对基于非结构重叠网格的naca0012翼型的定常流场以及简谐振荡的非定常流场进行了数值模拟,均取得了与实验数据符合良好的结果。
The exhaust system and muffler are simplified as a set of 1 - d pipes with non - isentropic flow and with variable sections . the partial differential equations of non - stationary flow are transferred into the stationary differential equations by means of the characteristic lines . these equations are solved by finite difference method 在排气管系的计算中将排气管简化为一组一维非等熵变截面管，并通过“特征线法”将描述其运动的非定常流的偏微分方程转化为常微分方程，再用差分数值方法依靠计算机求解。
Through solving the unsteady flow fields of an airfoil - flap , the mechanism of buzz is intensively studied . on the basis of the unsteady flow fields of an airfoil - flap with an upper - wing spoiler , the mechanism of the upper - wing spoiler suppressing the buzz is researched . in additions , the comparisons of the unsteady flow fields of an airfoil - flap with and without a separator show that the separator reduce the speed of the buzz 从非定常流场计算出发系统的研究了嗡鸣发生的机理以及扰流片对嗡鸣起抑制作用的机理；应用能量法确定了嗡鸣发生的边界；并且研究了机翼舵面之间有隔膜和无隔膜以及机翼上有上翼扰流片和无上翼扰流片对嗡鸣发生边界的影响；得出了有意义的结论。
According to non - newtonian fluid mechanics theory and mathematical method , conbined with plunger moving property , the hypothesize fluid is imcompressive , hydraulic radius of flow of liquid in crevice is very little , and it is laminar flow , the flow is treated fixed continuous flow at every instant position of plunger , equation of motion and boundary condition were set up in condition of concentric and eccentric of pump barrel and plunger 运用非牛顿流体力学理论和数理方法，结合抽油泵柱塞运动特点，假设液体为不可压缩的，液体在缝隙中流动的水力半径很小，呈层流流动，柱塞在每一位置的瞬间，流动做定常流处理，建立了泵筒与柱塞同心和偏心两种情况下运动方程和边界条件，引入无量纲坐标、无量纲速度和柱塞与泵筒偏心配合时的缝隙高度，并给出缝隙流流速、流量的解析解。
In modern aircraft design , there is an urgent requirement for accurate , efficient and easy - to - use numerical analysis tools . for this purpose , this thesis introduces recent progress in the generation and application of cartesian grid with tree data structure and adaptive refinement . coupled with hybrid grid techniques , euler and navier - stokes equations are solved 本文针对现代飞行器设计中对实用、高效、准确的气动力分析工具的迫切需求，基于叉树数据结构，发展了一种自适应直角切割网格方法，采用混合网格技术，实现了对流场euler和navier - stokes方程的计算求解，进一步完成了复杂增升装置绕流和外挂物分离投放非定常流场的数值模拟。
In this thesis , finite volume method and dual - time stepping method are employed to solve the 3 - d unsteady euler equations . the unsteady flow field around a finite - span flapping wing is simulated . the lift and thrust of the flapping wing for different cases are calculated 本文运用有限体积法结合双时间推进技术求解三维非定常欧拉方程，模拟了有限翼展机翼在同时具有上下拍动和俯仰运动状态下的非定常流场，计算了不同状态下扑翼的升力及推力，分析了各个影响因素对扑翼气动特性的影响。
In fact , the outlet flow of vane in the hydroelectric set is non - uniform flow for a variety of possible reasons . the flow is unsteady flow relative to vane and blade , and it is the main factor that affect self - excited vibration and dynamic characteristic of guide vane and hydraulic - turbine , which affect directly the power set to run safely and stably 非均匀来流相对于导叶、叶片必然是一种非定常流。这种非定常流造成导叶和转轮叶片的激振，是产生导叶和叶片动应力，改变它们频率的最主要因素，而导叶和叶片的动力特性直接影响水轮机的稳定性。
For practical purpose , an one - dimensional unsteady lumped model and a onedimensional unsteady stage - by - stage model , which are able to describe the dynamical post - stall behavior of compression systems , are derived firstly and then solved using the numerical methods to analyze the post - stall behavior and recoverability of compression systems . on the basis of characteristics of digital simulation of unsteady flow , the program for one - dimensional unsteady lumped model has compiled and tested under visual basic 6 . 0 environment completely . while the program for onedimensional unsteady stage - by - stage model has compiled and tested under foitran / visual basic mixed - language environment , which part of calculation is accomplished by fortran language 根据非定常流数值模拟的特点，通过可视化编程方法，用visualbasic6 . 0编写和调试了一维非定常总体模型的数值模拟程序；用visualbasic6 . 0制作界面，以fortran作为后台计算程序，编写和调试了一维非定常单元容积模型的数值模拟程序，成功地实现了vb与fortran的连接；使得数值模拟程序的界面友好，操作简单。
It indicates that the moving grid generation method used in this paper is simple , fast and easy to deal with the boundary conditions of the upstream and downstream . the use of the fully implicit dual - time stepping method in this paper can greatly decrease the calculating time of the three - dimensional unsteady flow in vibrating cascades to satisfy the engineering practice requirement . the efficiency of this acceleration method is very high 实践表明，本文的运动网格生成方法简单、快捷、便于进行上、下游边界条件处理，能够给出较准确的振动叶栅非定常流场解；本文计算采用的全隐式双时间方法将三维非定常粘流的计算时间降至工程可以接受的程度，加速效果十分突出。
