Broadband Fan Interaction Noise using Synthetic Inhomogeneous Non-stationary Turbulence

2011 ◽  
Author(s):  
Martina Dieste ◽  
Gwenael Gabard
Keyword(s):  
Stationary Turbulence

scholarly journals Acceleration and transport of ions in turbulent current sheets: formation of non-maxwelian energy distribution

2009 ◽  
Vol 16 (6) ◽  
pp. 631-639 ◽  
Author(s):  
A. V. Artemyev ◽  
L. M. Zelenyi ◽  
H. V. Malova ◽  
G. Zimbardo ◽  
D. Delcourt
Keyword(s):  
Electric Field ◽  
Particle Interaction ◽  
Average Energy ◽  
Average Particle ◽  
Acceleration Of Particles ◽  
Neutral Sheet ◽  
Energy Distributions ◽  
Stationary Turbulence ◽  
Reconnection Region ◽  
Transport Of Ions

Abstract. The paper is devoted to particle acceleration in turbulent current sheet (CS). Our results show that the mechanism of CS particle interaction with electromagnetic turbulence can explain the formation of power law energy distributions. We study the ratio between adiabatic acceleration of particles in electric field in the presence of stationary turbulence and acceleration due to electric field in the case of dynamic turbulence. The correlation between average energy gained by particles and average particle residence time in the vicinity of the neutral sheet is discussed. It is also demonstrated that particle velocity distributions formed by particle-turbulence interaction are similar in essence to the ones observed near the far reconnection region in the Earth's magnetotail.

scholarly journals A Lagrangian direct-interaction approximation for homogeneous isotropic turbulence

1997 ◽  
Vol 345 ◽  
pp. 307-345 ◽  
Author(s):  
SHIGEO KIDA ◽  
SUSUMU GOTO
Keyword(s):  
Energy Spectrum ◽  
Differential Equations ◽  
Isotropic Turbulence ◽  
Longitudinal Velocity ◽  
Direct Interaction ◽  
Homogeneous Isotropic Turbulence ◽  
Velocity Correlation ◽  
Stationary Turbulence ◽  
Direct Interaction Approximation ◽  
Velocity Derivative

A set of integro-differential equations in the Lagrangian renormalized approximation (Kaneda 1981) is rederived by applying a perturbation method developed by Kraichnan (1959), which is based upon an extraction of direct interactions among Fourier modes of a velocity field and was applied to the Eulerian velocity correlation and response functions, to the Lagrangian ones for homogeneous isotropic turbulence. The resultant set of integro-differential equations for these functions has no adjustable free parameters. The shape of the energy spectrum function is determined numerically in the universal range for stationary turbulence, and in the whole wavenumber range in a similarly evolving form for the freely decaying case. The energy spectrum in the universal range takes the same shape in both cases, which also agrees excellently with many measurements of various kinds of real turbulence as well as numerical results obtained by Gotoh et al. (1988) for a decaying case as an initial value problem. The skewness factor of the longitudinal velocity derivative is calculated to be −0.66 for stationary turbulence. The wavenumber dependence of the eddy viscosity is also determined.

A consequence of the zero fourth cumulant approximation

1962 ◽  
Vol 13 (3) ◽  
pp. 369-382 ◽  
Author(s):  
Edward E. O'Brien ◽  
George C. Francis
Keyword(s):  
Energy Spectrum ◽  
Numerical Computation ◽  
Root Mean Square ◽  
Isotropic Turbulence ◽  
Initial Conditions ◽  
Passive Scalar ◽  
Turbulent Energy ◽  
Length Scale ◽  
Mean Square ◽  
Stationary Turbulence

Recent investigations by Kraichnan (1961) and Ogura (1961) have raised doubts concerning the usefulness of the zero fourth cumulant approximation in turbulence dynamics. It appears extremely tedious to examine, by numerical computation, the consequences of this approximation on the turbulent energy spectrum although the appropriate equations have been established by Proudman & Reid (1954) and Tatsumi (1957). It has proved possible, however, to compute numerically the sequences of an analogous assumption when applied to an isotropic passive scalar in isotropic turbulence.The result of such computation, for specific initial conditions described herein, and for stationary turbulence, is that the scalar spectrum does develop negative values after a time approximately $2 \Lambda | {\overline {(u^2)}} ^{\frac {1}{2}}$, Where Λ is a length scale typical of the energy-containing components of both the turbulent and scalar spectra and $\overline {(u^2)}^{\frac {1}{2}}$ is the root mean square turbulent velocity.

On the weakly anisotropic nature of the time-stationary turbulence in the solar wind

2016 ◽  
Author(s):  
Xin Wang ◽  
Chuanyi Tu ◽  
Jiansen He ◽  
Eckart Marsch ◽  
Linghua Wang
Keyword(s):  
Solar Wind ◽  
Stationary Turbulence

ABOUT THE STATIONARY TURBULENCE REGIONS AND ANOMALOUS RESISTANCE IN THE MAGNETO-SPHERE PLASMA

1979 ◽  
Vol 40 (C7) ◽  
pp. C7-625-C7-626
Author(s):  
A. V. Volosevich ◽  
M. A. Livshits ◽  
V. A. Liperovsky ◽  
G. A. Skuridin
Keyword(s):  
Stationary Turbulence ◽  
Magneto Sphere
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