On the mechanism of turbulent coherent structure(II) —A physical model of coherent structure for the rough boundary layer

1996 ◽  
Vol 17 (3) ◽  
pp. 197-203 ◽  
Author(s):  
Liu Yulu ◽  
Cai Shutang
Keyword(s):  
Boundary Layer ◽  
Physical Model ◽  
Coherent Structure ◽  
Rough Boundary ◽  
Rough Boundary Layer ◽  
Turbulent Coherent Structure

scholarly journals Effect of drag reducing riblet surface on coherent structure in turbulent boundary layer

2019 ◽  
Vol 32 (11) ◽  
pp. 2433-2442 ◽  
Author(s):  
Guangyao CUI ◽  
Chong PAN ◽  
Di WU ◽  
Qingqing YE ◽  
Jinjun WANG
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Coherent Structure ◽  
Riblet Surface

scholarly journals On the decay of dispersive motions in the outer region of rough-wall boundary layers

2019 ◽  
Vol 862 ◽  
Author(s):  
Johan Meyers ◽  
Bharathram Ganapathisubramani ◽  
Raúl Bayoán Cal
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Boundary Layers ◽  
Outer Layer ◽  
Stokes Equations ◽  
Outer Region ◽  
Rough Wall ◽  
Rough Boundary ◽  
Mean Flow ◽  
Wall Boundary

In rough-wall boundary layers, wall-parallel non-homogeneous mean-flow solutions exist that lead to so-called dispersive velocity components and dispersive stresses. They play a significant role in the mean-flow momentum balance near the wall, but typically disappear in the outer layer. A theoretical framework is presented to study the decay of dispersive motions in the outer layer. To this end, the problem is formulated in Fourier space, and a set of governing ordinary differential equations per mode in wavenumber space is derived by linearizing the Reynolds-averaged Navier–Stokes equations around a constant background velocity. With further simplifications, analytically tractable solutions are found consisting of linear combinations of $\exp (-kz)$ and $\exp (-Kz)$, with $z$ the wall distance, $k$ the magnitude of the horizontal wavevector $\boldsymbol{k}$, and where $K(\boldsymbol{k},Re)$ is a function of $\boldsymbol{k}$ and the Reynolds number $Re$. Moreover, for $k\rightarrow \infty$ or $k_{1}\rightarrow 0$ (with $k_{1}$ the stream-wise wavenumber), $K\rightarrow k$ is found, in which case solutions consist of a linear combination of $\exp (-kz)$ and $z\exp (-kz)$, and are independent of the Reynolds number. These analytical relations are compared in the limit of $k_{1}=0$ to the rough boundary layer experiments by Vanderwel & Ganapathisubramani (J. Fluid Mech., vol. 774, 2015, R2) and are in reasonable agreement for $\ell _{k}/\unicode[STIX]{x1D6FF}\leqslant 0.5$, with $\unicode[STIX]{x1D6FF}$ the boundary-layer thickness and $\ell _{k}=2\unicode[STIX]{x03C0}/k$.

K-1408 Experimental Study on the Coherent Structure in the Turbulent Boundary Layer

2001 ◽  
Vol II.01.1 (0) ◽  
pp. 219-220
Author(s):  
Yasuhiko SAKAI ◽  
Takehiro KUSHIDA ◽  
Koji OHTA ◽  
Kazushige YOSHIDA ◽  
Hirokazu ITO
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Turbulent Boundary Layer ◽  
Coherent Structure

scholarly journals Modeling of Turbulent Fluid Flow Over a Rough Wall With or Without Suction

2003 ◽  
Vol 125 (4) ◽  
pp. 636-642 ◽  
Author(s):  
G. Gre´goire ◽  
M. Favre-Marinet ◽  
F. Julien Saint Amand
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Fluid Flow ◽  
Rough Boundary ◽  
Two Dimensional ◽  
Turbulent Fluid Flow ◽  
Boundary Layer Suction ◽  
Zonal Model ◽  
Impermeable Wall ◽  
Logarithmic Law

The turbulent flow close to a wall with two-dimensional roughness is computed with a two-layer zonal model. For an impermeable wall, the classical logarithmic law compares well with the numerical results if the location of the fictitious wall modeling the surface is considered at the top of the rough boundary. The model developed by Wilcox for smooth walls is modified to account for the surface roughness and gives satisfactory results, especially for the friction coefficient, for the case of boundary layer suction.

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