Evolution of isolated turbulent trailing vortices
Evolution of isolated turbulent trailing vortices
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孤立湍流尾涡的演化
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
S. Lele
中科院分区：
文献类型：
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作者：
K. Duraisamy;S. Lele
本文采用拟谱直接数值模拟方法研究了低旋数湍流Batchelor涡的时间演化。涡量-速度形式的控制方程的解允许边界条件的精确应用。物理的演变研究的重点是影响运输的轴向和角动量的机制。简正模不稳定性的激发在涡核内部产生相干的大尺度螺旋结构。这些螺旋结构的径向生长以及轴向剪切和差动旋转的作用导致了极化涡旋层的产生。该涡旋层演变成一系列发夹形结构，随后分解成细长的细尺度涡旋。最终，这些结构的径向向外传播导致流向稳定的高旋流构型的流动松弛。两个守恒量，基于偏离fr.
In this work, the temporal evolution of a low swirl-number turbulent Batchelor vortex is studied using pseudospectral direct numerical simulations. The solution of the governing equations in the vorticity-velocity form allows for accurate application of boundary conditions. The physics of the evolution is investigated with an emphasis on the mechanisms that influence the transport of axial and angular momentum. Excitation of normal mode instabilities gives rise to coherent large scale helical structures inside the vortical core. The radial growth of these helical structures and the action of axial shear and differential rotation results in the creation of a polarized vortex layer. This vortex layer evolves into a series of hairpin-shaped structures that subsequently breakdown into elongated fine scale vortices. Ultimately, the radially outward propagation of these structures results in the relaxation of the flow towards a stable high-swirl configuration. Two conserved quantities, based on the deviation fr...