It is found to locate at the top of stationary vortex . considerable growth rate of the mode is found and is responsible for the transition of boundary layer 它出现在流向速度型的拐点处，有着非常大的增长率，并造成附面层的转捩。
In the thesis the transition process of the plat on different mach numbers are calculated and the influence on the transition is discussed 文中对于不同马赫数下平板的转捩位置进行了计算，并和实验结果以及mack等的经典结果进行对比。
The new hair - pin vortex is formed continuous with psb disturbance , the breakup of hair - pin vortex makes the instability position of the strong by - pass transition is immobile and near the upstream of flow 由于psb强扰动不断激发新的发卡涡，而发卡涡的不断失稳导致了强扰动旁路转捩的失稳点靠近上游且空间位置基本固定。
The transition to the turbulent flow happened when the reynolds numbers ( based on the height of mini - channel ) were between 1200 and 1400 . and it was found that the critical reynolds numbers became larger when the friction - resistance factor got smaller 流动在雷诺数(通道高度雷诺数)为1200 1400时发生转捩，且摩阻越小的通道发生转捩的雷诺数越大。
The turbulent spots and coherent structures of . turbulent flow researched in the paper are an important discovery for the turbulent flow and transition , and the front problem in this field , and have important theoretic meaning and practical prospect 本文所研究的湍斑和湍流相干结构问题，是近代湍流及其转捩研究的重大发现，是该研究领域的前沿问题，有着重要的理论意义和应用前景。
The flow past a uniform circular cylinder is studied in detail by direct numerical simulations of three - dimensional incompressible navier - stokes equations . the features and dynamics for various reynolds numbers in the three - dimensional transition regime of the cylinder wake are investigated 本文以三维不可压缩粘性流体的navier - stokes方程为数学模型对圆柱绕流问题作直接数值模拟，研究圆柱尾迹三维转捩区间转捩特征和动力学过程。
The growth rate of inflectional instability and viscous instability also saturate similarly to the primary and nonlinearly generated disturbances . the main effect of inflectional instability mode in the final breakdown seems to interact with the disturbances having developed and thus widens the frequency spectrum to turbulent state 属于拐点不稳定性的高频二次不稳定模态对最后转捩的影响主要体现在与其它扰动的相互作用，并导致出现紊流状态宽带频谱。
While slug structure is leaving from computing domain , the successive disturbance develop in downstream direction , the legs of hair - pin vortex approach the wall continuously and induce vortex structures near the wall . the evolution of this near - wall vortex structures brings the secondary transition to turbulence in the pipe flow 随着塞流结构流出计算域，后继扰动向下游继续发展，表现为发卡涡的涡脚向壁面不断贴近，进而诱发近壁涡结构，近壁涡结构的进一步演化促使圆管流动出现二次转捩，发展到了湍流阶段。
In the thesis the low drag - low noise optimization of the vehicle main form design is realized , main accomplishments are as follows . researched the knowledge of drag and flow noise , the parameters of the boundary layer are calculated by the hess - smith method and boundary layer momentum integral method . the calculation of the length of transition zone and change in boundary layer displacement thickness between laminar and turbulent states in the transition is improved , then the drag coefficient and self - noise from the transition zone are calculated as the objective functions of the optimization 主要研究内容和成果如下：对航行器绕流流场进行分析，深入研究了阻力和流噪声产生机理，建立了阻力系数和自噪声的评估数值计算模型；采用物面分布源汇法和边界层动量积分法对绕流流场的流体动力参数进行计算，改进了转捩区长度和边界层位移厚度的计算，应用于航行器头部驻点自噪声的计算；最后设计了阻力系数和自噪声数值计算程序模块。
In view of the fact that the power of the nano technology and its many potential application in thermal science , the thesis mainly discussed the potential application of the nano technology in micro scale heat transfer , the stability of the nano particle suspension . experimental facility was designed and built up to study flow and heat transfer performance of cuo nano particle suspension and water in mini tubes 鉴于纳米技术表现出的强大生命力和在热科学领域中潜在的广阔应用前景，本文探讨了纳米悬浮液的稳定性，设计和建立了实验系统，实验研究了细圆管内氧化铜纳米颗粒悬浮液流动及换热特性，包括流动阻力特性，流动的转捩和换热特性。
