中文摘要：

本文主要研究三维亚音速流爬坡问题非平凡解的不存在性，在本文中，我们假设流体是等熵定常无旋的，也就是说，可以用定常的位势流方程来描述．通过建立三维角状区域中二阶线性椭圆方程Neumann边值的先验估计，我们证明在这样的区域中不存在全局非平凡的低马赫亚音速流．本文将已有结果中的区域推广到整个完全的三维角状区域．

英文摘要：

In this paper, we study the nonexistence of a global nontrivial subsonic solution in an unbounded 3D ramp Ω. The flow is assumed to be steady, isentropic and irrotational, namely, the movement of the flow is described by the potential equation. By establishing a prior estimate on the solution of the Laplace equation in Ω with Neumann boundary condition on δΩ, we prove that there is no global nontrivial subsonic flow with low Mach number in such domain. This paper extendes an existing result to a full 3D ramp case.