DNS of Fractal-Generated Turbulence
DNS of Fractal-Generated Turbulence
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DOI：
10.1007/s10494-011-9351-2
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发表时间：
2011-12-01
影响因子：
2.4
通讯作者：
Vassilicos, John Christos
中科院分区：
文献类型：
--
作者：
Laizet, Sylvain;Vassilicos, John Christos
采用一种新的方法，将高阶紧致格式、浸没边界法和高效的区域分解方法相结合，对规则网格和分形正方形网格生成的四种空间演化湍流流场进行了高保真度的直接数值模拟（DNS）。主要结果是：与规则网格相比，分形网格生成的涡量场更加密集，分形网格生成的涡量和湍流强度都比规则网格高;该流动在远下游保持清晰的分形网格的几何印记，这是未来可用于流动设计的特性，管理和被动控制;用分形网格获得的DNS证实了两个湍流区域的存在，其中一个湍流区域在靠近网格处逐渐放大（产生区域）之后是湍流衰减的区域;在流动的产生区域中的不同位置处的脉动紊流速度的能量谱提供了关于在不同的温度下紊流是如何产生的一些信息。最小尺度首先在最小尾流占主导地位的网格附近，随后是更远下游的逐渐变小的湍流频率，其中逐渐变大的尾流相互作用。
An innovative approach which combines high order compact schemes, Immersed Boundary Method and an efficient domain decomposition method is used to perform high fidelity Direct Numerical Simulations (DNS) of four spatially evolving turbulent flows, one generated by a regular grid and three generated by fractal square grids. The main results which we have been able to obtain from these simulations are the following: the vorticity field appears more clustered when generated by fractal square grids compared to a regular grid; fractal square grids generate higher vorticities and turbulence intensities than a regular grid; the flow holds clear geometrical imprints of the fractal grids far downstream, a property which could be used in the future for flow design, management and passive control; the DNS obtained with fractal grids confirmed the existence of two turbulent regions, one where the turbulence progressively amplifies closer to the grid (the production region) followed by one where the turbulence decays; the energy spectra of fluctuating turbulent velocities at various locations in the production region of the flow provide some information on how the turbulence is generated at the smallest scales first near the grid where the smallest wakes are dominant, followed by progressively smaller turbulent frequencies further downstream where progressively larger wakes interact.