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arXiv 2407.01038physics.flu-dyn
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剪切稀化射流中的2.5D湍流

2.5D turbulence in shear-thinning jets

Christian Amor, Giovanni Soligo, Andrea Mazzino, Marco Edoardo Rosti

AI总结:

针对剪切稀化流体湍流射流的维度转变问题,通过直接数值模拟揭示了垂直约束下2.5D混合维度湍流的形成机制、约束程度的调控作用及多级级联特性,为受限湍流动力学研究提供了新见解。

摘要:

本文通过直接数值模拟研究了剪切稀化流体湍流射流中的维度转变。研究结果表明,在垂直约束下,流体会呈现出独特的混合维度(即2.5D)状态,此时大尺度二维结构与小尺度三维结构共存。从入口附近的三维湍流到下游二维动力学的转变由约束程度决定:弱约束可保证湍流保持三维状态,强约束则会迫使湍流转变为二维状态;中等约束下会观测到混合维度状态,且该状态会在流动尺度大于垂直长度时立即出现。在这一场景下,我们观测到混合维度状态整体能量更高,且呈现多级级联过程,即小尺度能量的直接级联与大尺度拟涡能的直接级联共存。这些结果为受限湍流的复杂动力学研究提供了见解,该研究在自然环境与工业场景中均具有相关性。

英文摘要:

The dimensional transition in turbulent jets of a shear-thinning fluid is studied via direct numerical simulations. Our findings reveal that under vertical confinement, the flow exhibits a unique mixed-dimensional (or 2.5D) state, where large-scale two-dimensional and small-scale three-dimensional structures coexist. This transition from three-dimensional turbulence near the inlet to two-dimensional dynamics downstream is dictated by the level of confinement: weak confinement guarantees turbulence to remain three-dimensional, whereas strong confinement forces the transition to two-dimensions; the mixed-dimensional state is observed for moderate confinement and it emerges as soon as flow scales are larger than the vertical length. In this scenario, we observed that the mixed-dimensional state is an overall more energetic state and it shows a multi-cascade process, where the direct cascade of energy at small scales and the direct cascade of enstrophy at large scales coexist. The results provide insights into the complex dynamics of confined turbulent flows, relevant in both natural and industrial settings.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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