Asymptotic methods have been used to study a turbulent flat mixing layer comprising a viscous compressible gas flow descending from the trailing edge of a body and a gas at rest having the same chemical composition but a different temperature. In contrast to the existing methods for analysing turbulent flows using the Reynolds-averaged Navier-Stokes (RANS) equations, with some closure hypotheses, this paper considers the Navier-Stokes equations using known classic assumptions and facts. The characteristic Reynolds number of the flow is considered large, the thickness of the mixing layer is small, and the Mach numbers are limited within the range of ‘0–5’. The method of multiple scales allows a stationary (secondary) flow inside the turbulent mixing layer to be found and investigated as a principal part of the fluctuating solution. It is shown that the self-induced entrainment of gas from the external flow into the mixing layer is the main stationary flow that ensures the supply of kinetic energy from the zone of maximum speed to the turbulence generation area. It is also discovered that heat diffusion and the inflow of high-velocity gas from the external flow together determine the properties of the mixing layer. The Kolmogorov-scale and turbulence generation regions do not influence the stationary solution in the main approximation.

中文翻译：

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可压缩湍流混合层中的能量交换

渐近方法已用于研究湍流平坦混合层，该混合层包括从物体后缘下降的粘性可压缩气流和具有相同化学成分但温度不同的静止气体。与使用雷诺平均 Navier-Stokes (RANS) 方程分析湍流的现有方法相比，本文采用一些闭包假设，使用已知的经典假设和事实来考虑 Navier-Stokes 方程。认为流动的特征雷诺数大，混合层厚度小，马赫数限制在'0-5'范围内。多尺度方法允许发现湍流混合层内的静止（二次）流动，并将其作为波动溶液的主要部分进行研究。结果表明，气体从外流进入混合层的自诱导夹带是主要的静止流动，它确保了从最大速度区到湍流产生区的动能供应。还发现热扩散和来自外部流的高速气体的流入共同决定了混合层的性质。Kolmogorov 尺度和湍流生成区域不影响主近似中的平稳解。还发现热扩散和来自外部流的高速气体的流入共同决定了混合层的性质。Kolmogorov 尺度和湍流生成区域不影响主近似中的平稳解。还发现热扩散和来自外部流的高速气体的流入共同决定了混合层的性质。Kolmogorov 尺度和湍流生成区域不影响主近似中的平稳解。