Reynolds number dependence of the second-order turbulent pressure structure function

1999 ◽  
Vol 11 (1) ◽  
pp. 241-243 ◽  
Author(s):  
R. A. Antonia ◽  
D. K. Bisset ◽  
P. Orlandi ◽  
B. R. Pearson
Keyword(s):  
Reynolds Number ◽  
Structure Function ◽  
Second Order ◽  
Turbulent Pressure ◽  
Reynolds Number Dependence

Reynolds number dependence of second-order velocity structure functions

2000 ◽  
Vol 12 (11) ◽  
pp. 3000 ◽  
Author(s):  
R. A. Antonia ◽  
B. R. Pearson ◽  
T. Zhou
Keyword(s):  
Reynolds Number ◽  
Velocity Structure ◽  
Structure Functions ◽  
Second Order ◽  
Reynolds Number Dependence

scholarly journals Reynolds number dependence of Lyapunov exponents of turbulence and fluid particles

2021 ◽  
Vol 103 (3) ◽  
Author(s):  
Itzhak Fouxon ◽  
Joshua Feinberg ◽  
Petri Käpylä ◽  
Michael Mond
Keyword(s):  
Reynolds Number ◽  
Lyapunov Exponents ◽  
Fluid Particles ◽  
Reynolds Number Dependence

A Numerical Simulation Algorithm of the Inviscid Dynamics of Axisymmetric Swirling Flows in a Pipe

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
J. Granata ◽  
L. Xu ◽  
Z. Rusak ◽  
S. Wang
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Difference Scheme ◽  
Second Order ◽  
Swirling Flows ◽  
Inviscid Limit ◽  
Simulation Algorithm ◽  
Spatial Integration ◽  
Order Difference ◽  
Breakdown Process

Current simulations of swirling flows in pipes are limited to relatively low Reynolds number flows (Re < 6000); however, the characteristic Reynolds number is much higher (Re > 20,000) in most of engineering applications. To address this difficulty, this paper presents a numerical simulation algorithm of the dynamics of incompressible, inviscid-limit, axisymmetric swirling flows in a pipe, including the vortex breakdown process. It is based on an explicit, first-order difference scheme in time and an upwind, second-order difference scheme in space for the time integration of the circulation and azimuthal vorticity. A second-order Poisson equation solver for the spatial integration of the stream function in terms of azimuthal vorticity is used. In addition, when reversed flow zones appear, an averaging step of properties is applied at designated time steps. This adds slight artificial viscosity to the algorithm and prevents growth of localized high-frequency numerical noise inside the breakdown zone that is related to the expected singularity that must appear in any flow simulation based on the Euler equations. Mesh refinement studies show agreement of computations for various mesh sizes. Computed examples of flow dynamics demonstrate agreement with linear and nonlinear stability theories of vortex flows in a finite-length pipe. Agreement is also found with theoretically predicted steady axisymmetric breakdown states in a pipe as flow evolves to a time-asymptotic state. These findings indicate that the present algorithm provides an accurate prediction of the inviscid-limit, axisymmetric breakdown process. Also, the numerical results support the theoretical predictions and shed light on vortex dynamics at high Re.

Reynolds number dependence of turbulence statistics in the wake of wind turbines

Wind Energy ◽  
2011 ◽  
Vol 15 (5) ◽  
pp. 733-742 ◽  
Author(s):  
Leonardo P. Chamorro ◽  
R.E.A Arndt ◽  
F. Sotiropoulos
Keyword(s):  
Reynolds Number ◽  
Wind Turbines ◽  
Turbulence Statistics ◽  
Reynolds Number Dependence

Reynolds-number dependence of line and surface stretching in turbulence: folding effects

2007 ◽  
Vol 586 ◽  
pp. 59-81 ◽  
Author(s):  
SUSUMU GOTO ◽  
SHIGEO KIDA
Keyword(s):  
Reynolds Number ◽  
Time Scale ◽  
Isotropic Turbulence ◽  
Three Dimensional ◽  
Turnover Time ◽  
Material Object ◽  
Material Objects ◽  
Short Time Scale ◽  
Kolmogorov Scale ◽  
Reynolds Number Dependence

The stretching rate, normalized by the reciprocal of the Kolmogorov time, of sufficiently extended material lines and surfaces in statistically stationary homogeneous isotropic turbulence depends on the Reynolds number, in contrast to the conventional picture that the statistics of material object deformation are determined solely by the Kolmogorov-scale eddies. This Reynolds-number dependence of the stretching rate of sufficiently extended material objects is numerically verified both in two- and three-dimensional turbulence, although the normalized stretching rate of infinitesimal material objects is confirmed to be independent of the Reynolds number. These numerical results can be understood from the following three facts. First, the exponentially rapid stretching brings about rapid multiple folding of finite-sized material objects, but no folding takes place for infinitesimal objects. Secondly, since the local degree of folding is positively correlated with the local stretching rate and it is non-uniformly distributed over finite-sized objects, the folding enhances the stretching rate of the finite-sized objects. Thirdly, the stretching of infinitesimal fractions of material objects is governed by the Kolmogorov-scale eddies, whereas the folding of a finite-sized material object is governed by all eddies smaller than the spatial extent of the objects. In other words, the time scale of stretching of infinitesimal fractions of material objects is proportional to the Kolmogorov time, whereas that of folding of sufficiently extended material objects can be as long as the turnover time of the largest eddies. The combination of the short time scale of stretching of infinitesimal fractions and the long time scale of folding of the whole object yields the Reynolds-number dependence. Movies are available with the online version of the paper.

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