ABSTRACT Jets and plumes are shear flows created by momentum and buoyant sources. They can be classified as either pure jets, forced plumes, pure plumes, or lazy plumes. Lazy plumes are characterised as having a high source buoyancy flux relative to the momentum flux. We use direct numerical simulations to simulate lazy plumes to ascertain the effects of increasing plume ‘laziness’ on the higher order moments, such as Reynolds stresses, third order moments and turbulent kinetic energy budgets. The mildly lazy plumes behaved like most plumes in terms of higher order statistics: a self-similar collapse some distance downstream and peak values comparable to previous experiments and simulations. The highly lazy plumes did not show a self-similar collapse and, in most cases, had higher peak values in all moments. The highly lazy plumes had higher levels of turbulence intensities due to the high buoyancy flux, leading to significant buoyancy-induced turbulence production downstream.

中文翻译：

---

浮力对惰性羽流中高阶矩的影响

摘要 射流和羽流是由动量和浮力源产生的剪切流。它们可以分为纯喷射流、强制羽流、纯羽流或惰性羽流。惰性羽流的特征是相对于动量通量具有较高的源浮力通量。我们使用直接数值模拟来模拟惰性羽流，以确定增加羽流“惰性”对高阶矩的影响，例如雷诺应力、三阶矩和湍流动能预算。在高阶统计数据方面，轻度惰性羽流的行为与大多数羽流相似：自相似的坍塌下游一段距离，峰值与之前的实验和模拟相当。高度惰性的羽流没有表现出自相似的坍塌，并且在大多数情况下，在所有时刻都有更高的峰值。