Soft mode dynamics and spatio-temporal symmetry breaking in a thermo-convective system

1987 ◽  
Vol 68 (2-3) ◽  
pp. 265-269 ◽  
Author(s):  
T. Riste ◽  
K. Otnes
Keyword(s):  
Symmetry Breaking ◽  
Soft Mode ◽  
Convective System ◽  
Spatio Temporal ◽  
Temporal Symmetry

scholarly journals Spatio-temporal symmetry breaking in the flow past an oscillating cylinder

2021 ◽  
Vol 918 ◽  
Author(s):  
Puneet S. Matharu ◽  
Andrew L. Hazel ◽  
Matthias Heil
Keyword(s):  
Symmetry Breaking ◽  
Oscillating Cylinder ◽  
Flow Past ◽  
Spatio Temporal ◽  
Temporal Symmetry

Abstract

scholarly journals Disrupting the spatio-temporal symmetry of the electron dynamics in atmospheric pressure plasmas by voltage waveform tailoring

2019 ◽  
Vol 28 (1) ◽  
pp. 01LT01 ◽  
Author(s):  
Andrew R Gibson ◽  
Zoltán Donkó ◽  
Layla Alelyani ◽  
Lena Bischoff ◽  
Gerrit Hübner ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Electron Dynamics ◽  
Voltage Waveform ◽  
Atmospheric Pressure Plasmas ◽  
Spatio Temporal ◽  
Temporal Symmetry

scholarly journals Mode competition in modulated Taylor–Couette flow

2008 ◽  
Vol 601 ◽  
pp. 381-406 ◽  
Author(s):  
M. AVILA ◽  
M. J. BELISLE ◽  
J. M. LOPEZ ◽  
F. MARQUES ◽  
W. S. SARIC
Keyword(s):  
Couette Flow ◽  
Physical Experiment ◽  
Mode Competition ◽  
Taylor Vortex ◽  
Coexistence Region ◽  
Narrow Region ◽  
Taylor Couette ◽  
Spatio Temporal ◽  
Temporal Symmetry ◽  
Taylor Couette Flow

The effects of harmonically oscillating the inner cylinder about a zero mean rotation in a Taylor–Couette flow are investigated experimentally and numerically. The resulting time-modulated circular Couette flow possesses a Z2 spatio-temporal symmetry which gives rise to two distinct modulated Taylor vortex flows. These flows are initiated at synchronous bifurcations, have the same spatial symmetries, but are characterized by different spatio-temporal symmetries and axial wavenumber. Mode competition between these two states has been investigated in the region where they bifurcate simultaneously. In the idealized numerical model, the two flows have been found to coexist and be stable in a narrow region of parameter space. However, in the physical experiment, neither state has been observed in the coexistence region. Instead, we observe noise-sustained flows with irregular time-dependent axial wavenumber. Movies are available with the online version of the paper.

Flow over a thin circular disk at low to moderate Reynolds numbers

2008 ◽  
Vol 605 ◽  
pp. 253-262 ◽  
Author(s):  
A. R. SHENOY ◽  
C. KLEINSTREUER
Keyword(s):  
Lift Coefficient ◽  
Three Dimensional ◽  
Circular Disk ◽  
Vortex Structures ◽  
Separation Region ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Vortex Loops ◽  
Spatio Temporal ◽  
Temporal Symmetry

Computation of viscous flow over a circular disk of aspect ratio 10 (thickness/diameter) in the Reynolds number (Re) range of 10 to 300 was performed. The following flow regimes were observed: (I) steady axisymmetric flow when Re < 135, with the presence of a toroidal vortex behind the disk; (II) regular bifurcation with loss of azimuthal symmetry but with planar symmetry and a double-threaded wake, for 135 ≤ Re < 155; (III) three-dimensional flow with periodic shedding of double-sided hairpin-shaped vortex structures and periodic motion of the separation region for 155 ≤ Re < 172; (IV) regular shedding of double-sided hairpin-shaped vortex structures with planar and spatio-temporal symmetry for 172 ≤ Re < 280; (V) periodic three-dimensional flow with irregular rotation of the separation region when Re = 280–300. This transition process for the disk differs from that for the sphere as we observe a loss of the symmetry plane in Regime III due to a twisting motion of the axial vorticity strands in the wake of the disk. The periodic flow was characterized by double-sided hairpin structures, unlike the one-sided vortex loops observed for the sphere. This resulted in the drag coefficient oscillating at twice the frequency of the axial velocity. In Regime IV, the vortex loops were shed from diametrically opposite locations and with equal strength, resulting in the lift coefficient oscillating symmetrically about a zero mean. These results imply the presence of spatio-temporal symmetry.

scholarly journals Spatio-Temporal Symmetry—Point Groups with Time Translations

Symmetry ◽  
2017 ◽  
Vol 9 (9) ◽  
pp. 187 ◽  
Author(s):  
Haricharan Padmanabhan ◽  
Maggie Kingsland ◽  
Jason Munro ◽  
Daniel Litvin ◽  
Venkatraman Gopalan
Keyword(s):  
Symmetry Point ◽  
Point Groups ◽  
Spatio Temporal ◽  
Temporal Symmetry

Nonlinear mode interactions in a counter-rotating split-cylinder flow

2017 ◽  
Vol 816 ◽  
pp. 719-745 ◽  
Author(s):  
Paloma Gutierrez-Castillo ◽  
Juan M. Lopez
Keyword(s):  
Steady States ◽  
Mode Competition ◽  
Meridional Plane ◽  
Vortex Lines ◽  
Counter Rotation ◽  
Pulse Waves ◽  
Group Orbit ◽  
Spatio Temporal ◽  
Cylinder Flow ◽  
Temporal Symmetry

The flow in a split cylinder with each half in exact counter rotation is studied numerically. The exact counter rotation, quantified by a Reynolds number $\mathit{Re}$ based on the rotation rate and radius, imparts the system with an $O(2)$ symmetry (invariance to azimuthal rotations as well as to an involution consisting of a reflection about the mid-plane composed with a reflection about any meridional plane). The $O(2)$ symmetric basic state is dominated by a shear layer at the mid-plane separating the two counter-rotating bodies of fluid, created by the opposite-signed vortex lines emanating from the two endwalls being bent to meet at the split in the sidewall. With the exact counter rotation, the additional involution symmetry allows for steady non-axisymmetric states, that exist as a group orbit. Different members of the group simply correspond to different azimuthal orientations of the same flow structure. Steady states with azimuthal wavenumber $m$ (the value of $m$ depending on the cylinder aspect ratio $\unicode[STIX]{x1D6E4}$) are the primary modes of instability as $\mathit{Re}$ and $\unicode[STIX]{x1D6E4}$ are varied. Mode competition between different steady states ensues, and further bifurcations lead to a variety of different time-dependent states, including rotating waves, direction-reversing waves, as well as a number of slow–fast pulse waves with a variety of spatio-temporal symmetries. Further from the primary instabilities, the competition between the vortex lines from each half-cylinder settles on either a $m=2$ steady state or a limit cycle state with a half-period-flip spatio-temporal symmetry. By computing in symmetric subspaces as well as in the full space, we are able to unravel many details of the dynamics involved.

Notizen: Comparison Between a Generic Reaction- Diffusion Model and a Synergetic Semiconductor System

1987 ◽  
Vol 42 (6) ◽  
pp. 655-656
Author(s):  
J. Parisi ◽  
J. Peinke ◽  
B. Röhricht ◽  
U. Rau ◽  
M. Klein ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Diffusion Model ◽  
Physical Interpretation ◽  
Reaction Diffusion ◽  
Dynamical Model ◽  
Nonlinear Transport ◽  
Reaction Diffusion Model ◽  
Semiconductor System ◽  
Spatio Temporal ◽  
Simple Dynamical Model

This paper gives a concrete physical interpretation of a simple dynamical model based on the universal Rashevsky- Turing theory of symmetry-breaking morphogenesis in terms of spatio-temporal nonlinear transport phenomena in a synergetic semiconductor system.

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