scholarly journals Two-Point Statistics of Coherent Structure in Turbulent Flow

2019 ◽  
Vol 07 (04) ◽  
pp. 153-173
Author(s):  
Jun Chen
Keyword(s):  
Turbulent Flow ◽  
Coherent Structure

scholarly journals On coherent structure in wall turbulence

2013 ◽  
Vol 728 ◽  
pp. 196-238 ◽  
Author(s):  
A. S. Sharma ◽  
B. J. McKeon
Keyword(s):  
Turbulent Flow ◽  
Coherent Structure ◽  
Stokes Equations ◽  
Travelling Waves ◽  
Full Range ◽  
Wall Turbulence ◽  
Critical Layer ◽  
Taylor’S Hypothesis ◽  
Response Modes ◽  
Low Dimensional

AbstractA new theory of coherent structure in wall turbulence is presented. The theory is the first to predict packets of hairpin vortices and other structure in turbulence, and their dynamics, based on an analysis of the Navier–Stokes equations, under an assumption of a turbulent mean profile. The assumption of the turbulent mean acts as a restriction on the class of possible structures. It is shown that the coherent structure is a manifestation of essentially low-dimensional flow dynamics, arising from a critical-layer mechanism. Using the decomposition presented in McKeon & Sharma (J. Fluid Mech., vol. 658, 2010, pp. 336–382), complex coherent structure is recreated from minimal superpositions of response modes predicted by the analysis, which take the form of radially varying travelling waves. The leading modes effectively constitute a low-dimensional description of the turbulent flow, which is optimal in the sense of describing the resonant effects around the critical layer and which minimally predicts all types of structure. The approach is general for the full range of scales. By way of example, simple combinations of these modes are offered that predict hairpins and modulated hairpin packets. The example combinations are chosen to represent observed structure, consistent with the nonlinear triadic interaction for wavenumbers that is required for self-interaction of structures. The combination of the three leading response modes at streamwise wavenumbers $6, ~1, ~7$ and spanwise wavenumbers $\pm 6, ~\pm 6, ~\pm 12$, respectively, with phase velocity $2/ 3$, is understood to represent a turbulence ‘kernel’, which, it is proposed, constitutes a self-exciting process analogous to the near-wall cycle. Together, these interactions explain how the mode combinations may self-organize and self-sustain to produce experimentally observed structure. The phase interaction also leads to insight into skewness and correlation results known in the literature. It is also shown that the very large-scale motions act to organize hairpin-like structures such that they co-locate with areas of low streamwise momentum, by a mechanism of locally altering the shear profile. These energetic streamwise structures arise naturally from the resolvent analysis, rather than by a summation of hairpin packets. In addition, these packets are modulated through a ‘beat’ effect. The relationship between Taylor’s hypothesis and coherence is discussed, and both are shown to be the consequence of the localization of the response modes around the critical layer. A pleasing link is made to the classical laminar inviscid theory, whereby the essential mechanism underlying the hairpin vortex is captured by two obliquely interacting Kelvin–Stuart (cat’s eye) vortices. Evidence for the theory is presented based on comparison with observations of structure in turbulent flow reported in the experimental and numerical simulation literature and with exact solutions reported in the transitional literature.

G105 Study on Coherent Structure of Turbulent Flow over a Wavy Wall

2009 ◽  
Vol 2009 (0) ◽  
pp. 541-542
Author(s):  
Kentaro Tanaka ◽  
Shinji Nakagawa ◽  
Masaru Ishizuka
Keyword(s):  
Turbulent Flow ◽  
Coherent Structure ◽  
Wavy Wall

POD Analysis of Coherent Structure in Turbulent Flow after Micro Vortex Generator

2021 ◽  
Author(s):  
Xuan My Trieu ◽  
Jianming Liu ◽  
Yisheng Gao ◽  
Sita Charkrit ◽  
Chaoqun Liu
Keyword(s):  
Turbulent Flow ◽  
Coherent Structure ◽  
Vortex Generator ◽  
Pod Analysis ◽  
Micro Vortex Generator

529 Coherent Structure in Wall Turbulent Flow

2001 ◽  
Vol 2001.7 (0) ◽  
pp. 423-424
Author(s):  
Isao MISU ◽  
Atsushi SATO ◽  
Toshimasa HIRATA ◽  
Hirotaka OTSUKA
Keyword(s):  
Turbulent Flow ◽  
Coherent Structure

scholarly journals Characteristic of coherent structure of turbulent flow in straight-eandering open channel

1993 ◽  
Vol 37 ◽  
pp. 475-480
Author(s):  
Katsutoshi WATANABE ◽  
Takanori SAGA ◽  
Hirofumi OHNARI ◽  
Takashi SAITOU
Keyword(s):  
Turbulent Flow ◽  
Coherent Structure ◽  
Open Channel

An Introduction to Turbulent Flow

2000 ◽  
Author(s):  
Jean Mathieu ◽  
Julian Scott
Keyword(s):  
Turbulent Flow

Modal Analysis of Turbulent Flow near an Inclined Bank–Longitudinal Structure Junction

2021 ◽  
Vol 147 (3) ◽  
pp. 04020100
Author(s):  
Nasser Heydari ◽  
Panayiotis Diplas ◽  
J. Nathan Kutz ◽  
Soheil Sadeghi Eshkevari
Keyword(s):  
Turbulent Flow ◽  
Modal Analysis ◽  
Longitudinal Structure
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