Continuous Subsonic-Sonic Flows in a Convergent Nozzle  

作　　者：Yuan Yuan NIE Chun Peng WANG 

机构地区：[1]School of Mathematics, Jilin University

出　　处：《Acta Mathematica Sinica,English Series》2018年第4期749-772,共24页数学学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China(Grant Nos.11571137 and 11601182)

摘　　要：This paper concerns continuous subsonic-sonic potential flows in a two-dimensional conver- gent nozzle. It is shown that for a given nozzle which is a perturbation of a straight one, a given point on its wall where the curvature is zero, and a given inlet which is a perturbation of an arc centered at the vertex, there exists uniquely a continuous subsonic-sonic flow whose velocity vector is along the normal direction at the inlet and the sonic curve, which satisfies the slip conditions on the nozzle walls and whose sonic curve intersects the upper wall at the given point. Furthermore, the sonic curve of this flow is a free boundary, where the flow is singular in the sense that the speed is only C1/2 H6lder continuous and the acceleration blows up. The perturbation problem is solved in the potential plane, where the flow is governed by a free boundary problem of a degenerate elliptic equation with two free boundaries and two nonlocal boundary conditions, and the equation is degenerate at one free boundary.This paper concerns continuous subsonic-sonic potential flows in a two-dimensional conver- gent nozzle. It is shown that for a given nozzle which is a perturbation of a straight one, a given point on its wall where the curvature is zero, and a given inlet which is a perturbation of an arc centered at the vertex, there exists uniquely a continuous subsonic-sonic flow whose velocity vector is along the normal direction at the inlet and the sonic curve, which satisfies the slip conditions on the nozzle walls and whose sonic curve intersects the upper wall at the given point. Furthermore, the sonic curve of this flow is a free boundary, where the flow is singular in the sense that the speed is only C1/2 H6lder continuous and the acceleration blows up. The perturbation problem is solved in the potential plane, where the flow is governed by a free boundary problem of a degenerate elliptic equation with two free boundaries and two nonlocal boundary conditions, and the equation is degenerate at one free boundary.

关 键 词：Continuous subsonic-sonic flow free boundary nonlocal boundary condition degeneracy singularity 

分 类 号：O354.1[理学—流体力学]