The variation of large-scale structure inclination angles in high Reynolds number atmospheric surface layers

2017 ◽  
Vol 29 (3) ◽  
pp. 035104 ◽  
Author(s):  
Hong-You Liu ◽  
Tian-Li Bo ◽  
Yi-Rui Liang
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Surface Layers ◽  
Inclination Angles ◽  
High Reynolds

Fine Structure of Vortex Sheet Rollup by Viscous and Inviscid Simulation

1991 ◽  
Vol 113 (1) ◽  
pp. 31-36 ◽  
Author(s):  
G. Tryggvason ◽  
W. J. A. Dahm ◽  
K. Sbeih
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Large Scale ◽  
Stokes Equations ◽  
Flow Region ◽  
Vortex Sheet ◽  
Navier Stokes ◽  
Vortex Sheets ◽  
Limiting Behavior ◽  
High Reynolds

Numerical simulations of the large amplitude stage of the Kelvin-Helmholtz instability of a relatively thin vorticity layer are discussed. At high Reynolds number, the effect of viscosity is commonly neglected and the thin layer is modeled as a vortex sheet separating one potential flow region from another. Since such vortex sheets are susceptible to a short wavelength instability, as well as singularity formation, it is necessary to provide an artificial “regularization” for long time calculations. We examine the effect of this regularization by comparing vortex sheet calculations with fully viscous finite difference calculations of the Navier-Stokes equations. In particular, we compare the limiting behavior of the viscous simulations for high Reynolds numbers and small initial layer thickness with the limiting solution for the roll-up of an inviscid vortex sheet. Results show that the inviscid regularization effectively reproduces many of the features associated with the thickness of viscous vorticity layers with increasing Reynolds number, though the simplified dynamics of the inviscid model allows it to accurately simulate only the large scale features of the vorticity field. Our results also show that the limiting solution of zero regularization for the inviscid model and high Reynolds number and zero initial thickness for the viscous simulations appear to be the same.

Very Large-Scale Structures and Their Effects on the Wall Shear-Stress Fluctuations in a Turbulent Channel Flow up to Reτ=640

2004 ◽  
Vol 126 (5) ◽  
pp. 835-843 ◽  
Author(s):  
Hiroyuki Abe ◽  
Hiroshi Kawamura ◽  
Haecheon Choi
Keyword(s):  
Reynolds Number ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
High Reynolds Number ◽  
Large Scale ◽  
Turbulent Channel Flow ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Wall Shear ◽  
High Reynolds

Direct numerical simulation of a fully developed turbulent channel flow has been carried out at three Reynolds numbers, 180, 395, and 640, based on the friction velocity and the channel half width, in order to investigate very large-scale structures and their effects on the wall shear-stress fluctuations. It is shown that very large-scale structures exist in the outer layer and that they certainly contribute to inner layer structures at high Reynolds number. Moreover, it is revealed that very large-scale structures exist even in the wall shear-stress fluctuations at high Reynolds number, which are essentially associated with the very large-scale structures in the outer layer.

Anisotropy of small-scale scalar turbulence

2001 ◽  
Vol 448 ◽  
pp. 279-288 ◽  
Author(s):  
SUSAN KURIEN ◽  
KONSTANTINOS G. AIVALIS ◽  
KATEPALLI R. SREENIVASAN
Keyword(s):  
Reynolds Number ◽  
Spherical Harmonics ◽  
High Reynolds Number ◽  
Temperature Fluctuations ◽  
Small Scale ◽  
Surface Layers ◽  
Isotropic Part ◽  
Scalar Turbulence ◽  
Scale Temperature ◽  
High Reynolds

The anisotropy of small-scale temperature fluctuations in shear flows is analysed by making measurements in high-Reynolds-number atmospheric surface layers. A spherical harmonics representation of the moments of scalar increments is proposed, such that the isotropic part corresponds to the index j = 0 and increasing degrees of anisotropy correspond to increasing j. The parity and angular dependence of the odd moments of the scalar increments show that the moments cannot contain any isotropic part (j = 0), but can be satisfactorily represented by the lowest-order anisotropic term corresponding to j = 1. Thus, the skewnesses of scalar increments (and derivatives) are inherently anisotropic quantities, and are not suitable indicators of the tendency towards isotropy.

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