Three-dimensional ideal gas flows behind a detached bow shock wave near the nonsymmetrical nose part of a bluff body in a uniform supersonic flow are investigated. The vector lines of the vector product of the velocity and entropy gradient are considered on isentropic surfaces, which are stream surfaces starting on closed lines located on the shock wave and covering the leading point of the shock wave. It is shown that if these vector lines encircle the isentropic surface they are closed. This means that an orthogonal curvilinear coordinate system in which the coordinate lines coincide with the streamlines may be constructed on each isentropic surface.

中文翻译：

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分离弓形冲击波后等熵面上的正交曲线坐标系

研究了在均匀超声速流中钝体非对称鼻部附近分离的弓形激波后面的三维理想气体流动。在等熵表面上考虑速度和熵梯度的矢量乘积的矢量线，这些表面是从位于激波上的闭合线开始并覆盖激波的前导点的流表面。结果表明，如果这些矢量线环绕等熵面，则它们是封闭的。这意味着可以在每个等熵面上构建一个正交曲线坐标系，其中坐标线与流线重合。