An experimental study of non-linear interaction of velocity fluctuations in the transition region of a two-dimensional wake

1970 ◽  
Vol 44 (04) ◽  
pp. 741 ◽  
Author(s):  
Hiroshi Sato
Keyword(s):  
Experimental Study ◽  
Transition Region ◽  
Two Dimensional ◽  
Linear Interaction ◽  
Velocity Fluctuations ◽  
Non Linear

Turbulent-like velocity fluctuations in two-dimensional granular materials subject to cyclic shear

Soft Matter ◽  
2022 ◽  
Author(s):  
Aile Sun ◽  
Yinqiao Wang ◽  
Yangrui Chen ◽  
Jin Shang ◽  
Jie Zheng ◽  
...  
Keyword(s):  
Experimental Study ◽  
Granular Materials ◽  
Granular Matter ◽  
Two Dimensional ◽  
Friction Coefficients ◽  
Velocity Fluctuations ◽  
Cyclic Shear

We perform a systematic experimental study to investigate the velocity fluctuations in the two-dimensional granular matter of low and high friction coefficients subjected to cyclic shear of a range of...

Fine-structure of energy spectra of velocity fluctuations in the transition region of a two-dimensional wake

1975 ◽  
Vol 67 (3) ◽  
pp. 539-559 ◽  
Author(s):  
Hiroshi Sato ◽  
Hironosuke Saito
Keyword(s):  
Fine Structure ◽  
Transition Region ◽  
Nonlinear Interaction ◽  
Spectral Component ◽  
Random Fluctuation ◽  
Band Pass Filter ◽  
Two Dimensional ◽  
Pass Filter ◽  
Velocity Fluctuations ◽  
Random Components

Measurements of the fine-structure of the energy spectrum of the velocity fluctuations were made in the transition region of a two-dimensional wake. Line and continuous spectra were determined separately with a high-selectivity band-pass filter. The transition was initiated by an external sinusoidal sound. The sound-induced periodic fluctuation and the natural random fluctuation in the wake were added and a system of line and continuous spectra was formed. Higher harmonics of the periodic component were produced by the nonlinear interaction. As a result of the interaction between discrete and continuous components, a continuous spectrum was generated at low wavenumbers. A simple model for the interaction is proposed. The evolution of the spectrum is explained by three fundamental rules concerning the nonlinear interaction between spectral components: (i) the growth of a spectral component is suppressed by the presence of another strong component, (ii) mutual interaction is more effective when the amplitudes of interacting components are closer, and (iii) a stronger interaction takes place between components of closer wavenumbers. The randomization of the regular fluctuation is properly expressed as the growth of the ‘randomness factor’, the ratio of the energy of the random components to the total fluctuation energy.

scholarly journals Two-dimensional simulations of internal gravity waves in the radiation zones of intermediate-mass stars

2020 ◽  
Vol 497 (4) ◽  
pp. 4231-4245 ◽  
Author(s):  
R P Ratnasingam ◽  
P V F Edelmann ◽  
T M Rogers
Keyword(s):  
Gravity Waves ◽  
Internal Gravity Waves ◽  
Two Dimensional ◽  
Intermediate Mass ◽  
Single Wave ◽  
Linear Interaction ◽  
Generation Spectrum ◽  
Non Linear ◽  
Hydrodynamical Simulations ◽  
Spectrum Slope

ABSTRACT Intermediate-mass main-sequence stars have large radiative envelopes overlying convective cores. This configuration allows internal gravity waves (IGWs) generated at the convective–radiative interface to propagate towards the stellar surface. The signatures of these waves can be observed in the photometric and spectroscopic data from stars. We have studied the propagation of these IGWs using two-dimensional (2D) fully non-linear hydrodynamical simulations with realistic stellar reference states from the 1D stellar evolution code, Modules for Stellar Astrophysics (mesa). When a single wave is forced, we observe wave self-interaction. When two waves are forced, we observe non-linear interaction (i.e. triadic interaction) between these waves forming waves at different wavelengths and frequencies. When a spectrum of waves similar to that found in numerical simulations is forced, we find that the surface IGW frequency slope is consistent with recent observations. This power law is similar to that predicted by linear theory for the wave propagation, with small deviations that can be an effect of non-linearities. When the same generation spectrum is applied to 3 M⊙ models at different stellar rotation and ages, the surface IGW spectrum slope is very similar to the generation spectrum slope.

The formation of vortex streets

1962 ◽  
Vol 13 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Frederick H. Abernathy ◽  
Richard E. Kronauer
Keyword(s):  
Incompressible Fluid ◽  
Vortex Street ◽  
Bluff Bodies ◽  
Two Dimensional ◽  
Vortex Sheets ◽  
Linear Interaction ◽  
Inviscid Incompressible Fluid ◽  
Fixed Distance ◽  
Vortex Streets ◽  
Non Linear

The formation of vortex streets in the wake of two-dimensional bluff bodies can be explained by considering the non-linear interaction of two infinite vortex sheets, initially a fixed distance, h, apart, in an inviscid incompressible fluid. The interaction of such sheets (represented in the calculation by rows of point-vortices) is examined in detail for various ratios of h to the wavelength, a, of the initial disturbance. The number and strength of the concentrated regions of vorticity formed in the interaction depend very strongly on h/a. The non-linear interaction of the two vortex sheets explains both the cancellation of vorticity and vortex-street broadening observed in the wakes of bluff bodies.

Non-Linear Interaction of MHD Waves with Small-Scale Ionospheric Irregularities

2004 ◽  
Vol 61 (7-12) ◽  
pp. 1055-1071
Author(s):  
N. N. Gerasimova ◽  
V. G. Sinitsin ◽  
Yu. M. Yampolski
Keyword(s):  
Ionospheric Irregularities ◽  
Mhd Waves ◽  
Small Scale ◽  
Linear Interaction ◽  
Non Linear
Sign in / Sign up

Export Citation Format

Share Document