中文摘要：

人们虽然对层流向湍流转捩过程的研究已经付出了许多艰辛的努力,但仍然有一个重要的物理现象还没有弄清楚,即有压梯度边界层转捩过程中湍流斑形成的理论机制以及湍流斑的运动特征是什么？这些问题正有待于人们做进一步的深入探索。本文提出一种以壁面局部脉冲的初始小扰动场来模拟有压梯度边界层流中湍流斑形成的物理模型,采用直接数值模拟的方法研究有压梯度边界层流中湍流斑产生的理论机制和发展规律;数值结果显示,它们在好多方面与湍流斑的基本特征相符。

英文摘要：

People who have paid great efforts,study on transition from laminar flow to turbulence.However,the theoretical mechanism and the features of turbulent spots in the process of the transition in a boundary layer with pressure gradient have not yet been clarified,thus needs to be further explored.A physical mode of the formation of turbulent spots in the boundary layer with pressure gradient,which is a small initial disturbance field induced by local impulse at the wall,is presented in the paper.Using direct numerical simulation,we study the physical mechanism and evolution of the formation of turbulent spots in the boundary layer with pressure gradient.The numerical results are consistent with characteristics of turbulent spots in many respects.