Acta mathematica scientia,Series A ›› 2023, Vol. 43 ›› Issue (3): 691-701.

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Existence of Back-Flow Point for the Two-Dimensional Compressible Prandtl Equation

Zou Yonghui(),Xu Xin*()   

  1. School of Mathematical Sciences, Ocean University of China, Shandong Qingdao 266100
  • Received:2022-09-27 Revised:2022-11-28 Online:2023-06-26 Published:2023-06-01
  • Contact: Xin Xu E-mail:zouyonghuimath@163.com;xx@ouc.edu.cn
  • Supported by:
    NSFC(12001506)

Abstract:

In this paper, we study the back-flow problem of the two-dimensional unsteady compressible Prandtl boundary layer equations. By using the maximum principle, we obtain that a first back-flow point should appear on the boundary $\left\{y=0\right\}$ if back-flow occurs under Oleinik's monotonicity assumption. Moreover, when the pressure gradient of the outer flow is adverse and the initial velocity satisfies certain growth condition, we obtain the existence of a back-flow point of the compressible Prandtl boundary layer by Lyapunov functional method. Finally, an example of the existence of the back-flow point is given.

Key words: Compressible Prandtl equation, Back-flow point, The maximum principle, Adverse pressure gradient, Lyapunov functional

CLC Number: 

  • O175.29
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