Large eddy simulations of a turbulent channel flow with a deforming wall undergoing high steepness traveling waves
Large eddy simulations of a turbulent channel flow with a deforming wall undergoing high steepness traveling waves
复制标题
经历高陡度行波的变形壁湍流通道流的大涡模拟
DOI：
10.1063/1.5131268
复制
发表时间：
2019
影响因子：
4.6
通讯作者：
I. Borazjani
中科院分区：
文献类型：
--
作者：
A. Akbarzadeh;I. Borazjani
众所周知，在完全发展的湍流通道的壁上向后行波可以降低阻力系数、流动分离和湍流强度。基于先前对小陡度行波（s = a/λ < 0.0625，a：无量纲振幅，λ：无量纲波长）的研究，认为无量纲波速（C = C * / U *，C *：有量纲波速，U *：平均通道速度）必须大于1才能实现零净阻力和高湍流动能（TKE）降低。这里使用完全发展的湍流通道的大涡模拟，对不同波速下具有较高波陡度 (0.05 < s < 0.15) 的波测试了这一想法，其中一个壁正在经历行波。研究发现，波陡度的增加会降低获得净零阻力时的波速，例如，对于陡度为 s = 0.05、0.075 和 0.15 的波，波速分别约为 C = 1.6 ± 0.1、0.9 ± 0.1 和 0.7 ± 0.1。类似地，波陡度的增加降低了波速，在该波速下，波附近的流动的 TKE 被大大降低，例如，定性地最小化。事实上，在本研究中，对于波陡度为 0.05、0.075 和 0.15 的波，TKE 大幅降低的波速分别为 C = 1.2、1.2 和 0.6。众所周知，在完全发达的湍流通道壁上向后行波可以降低阻力系数、流动分离和湍流强度。基于先前对小陡度行波（s = a/λ < 0.0625，a：无量纲振幅，λ：无量纲波长）的研究，认为无量纲波速（C = C * / U *，C *：有量纲波速，U *：平均通道速度）必须大于1才能实现零净阻力和高湍流动能（TKE）降低。这里使用完全发展的湍流通道的大涡模拟，对不同波速下具有较高波陡度 (0.05 < s < 0.15) 的波测试了这一想法，其中一个壁正在经历行波。研究发现，波陡度的增加会降低获得净零阻力时的波速，例如，对于陡度为 s = 0.05、0.075 和 0.15 的波，波速分别约为 C = 1.6 ± 0.1、0.9 ± 0.1 和 0.7 ± 0.1...
Backward traveling waves over a wall of a fully developed turbulent channel are known to reduce the drag coefficient, flow separation, and turbulence intensity. Based on previous studies of traveling waves with a small steepness (s = a/λ < 0.0625, a: nondimensional amplitude, λ: nondimensional wavelength), it is thought that the nondimensional wave-speed (C = C*/U*, C*: dimensional wave-speed, U*: mean channel velocity) is required to be more than one to have a zero net drag and a high reduction in the turbulent kinetic energy (TKE). This idea is tested here for waves with higher wave steepness (0.05 < s < 0.15) at various wave-speeds using large eddy simulations of a fully developed turbulent channel in which one wall is undergoing a traveling wave. It is found that the increase in wave steepness decreases the wave-speed at which a net zero drag is obtained, e.g., for waves with steepness of s = 0.05, 0.075, and 0.15, the wave-speed is, approximately, C = 1.6 ± 0.1, 0.9 ± 0.1, and 0.7 ± 0.1, respectively. Similarly, the increase in wave steepness decreases the wave-speed at which TKE of the flow in the vicinity of the wave is highly reduced, e.g., qualitatively minimized. In fact, the wave-speeds at which the high reduction in TKE is observed in this study are C = 1.2, 1.2, and 0.6 for waves with wave steepness of 0.05, 0.075, and 0.15, respectively.Backward traveling waves over a wall of a fully developed turbulent channel are known to reduce the drag coefficient, flow separation, and turbulence intensity. Based on previous studies of traveling waves with a small steepness (s = a/λ < 0.0625, a: nondimensional amplitude, λ: nondimensional wavelength), it is thought that the nondimensional wave-speed (C = C*/U*, C*: dimensional wave-speed, U*: mean channel velocity) is required to be more than one to have a zero net drag and a high reduction in the turbulent kinetic energy (TKE). This idea is tested here for waves with higher wave steepness (0.05 < s < 0.15) at various wave-speeds using large eddy simulations of a fully developed turbulent channel in which one wall is undergoing a traveling wave. It is found that the increase in wave steepness decreases the wave-speed at which a net zero drag is obtained, e.g., for waves with steepness of s = 0.05, 0.075, and 0.15, the wave-speed is, approximately, C = 1.6 ± 0.1, 0.9 ± 0.1, and 0.7 ± 0.1, respectively...