Physical Mechanism of the Two-Dimensional Enstrophy Cascade

2003 ◽  
Vol 91 (21) ◽  
Author(s):  
Shiyi Chen ◽  
Robert E. Ecke ◽  
Gregory L. Eyink ◽  
Xin Wang ◽  
Zuoli Xiao
Keyword(s):  
Physical Mechanism ◽  
Two Dimensional ◽  
Enstrophy Cascade

scholarly journals A numerical study of the interaction between two ejecta in the interplanetary medium: one- and two-dimensional hydrodynamic simulations

2004 ◽  
Vol 22 (10) ◽  
pp. 3741-3749 ◽  
Author(s):  
A. Gonzalez-Esparza ◽  
A. Santillán ◽  
J. Ferrer
Keyword(s):  
Hydrodynamic Model ◽  
Physical Mechanism ◽  
Interplanetary Medium ◽  
Numerical Study ◽  
Two Dimensions ◽  
Magnetic Clouds ◽  
The Sun ◽  
Two Dimensional ◽  
Hydrodynamic Simulations

Abstract. We studied the heliospheric evolution in one and two dimensions of the interaction between two ejecta-like disturbances beyond the critical point: a faster ejecta 2 overtaking a previously launched slower ejecta 1. The study is based on a hydrodynamic model using the ZEUS-3-D code. This model can be applied to those cases where the interaction occurs far away from the Sun and there is no merging (magnetic reconnection) between the two ejecta. The simulation shows that when the faster ejecta 2 overtakes ejecta 1 there is an interchange of momentum between the two ejecta, where the leading ejecta 1 accelerates and the tracking ejecta 2 decelerates. Both ejecta tend to arrive at 1AU having similar speeds, but with the front of ejecta 1 propagating faster than the front of ejecta 2. The momentum is transferred from ejecta 2 to ejecta 1 when the shock initially driven by ejecta 2 passes through ejecta 1. Eventually the two shock waves driven by the two ejecta merge together into a single stronger shock. The 2-D simulation shows that the evolution of the interaction can be very complex and there are very different signatures of the same event at different viewing angles; however, the transferring of momentum between the two ejecta follows the same physical mechanism described above. These results are in qualitative agreement with in-situ plasma observations of "multiple magnetic clouds" detected at 1AU.

Charney isotropy and equipartition in quasi-geostrophic turbulence

2010 ◽  
Vol 656 ◽  
pp. 448-457 ◽  
Author(s):  
ANDREAS VALLGREN ◽  
ERIK LINDBORG
Keyword(s):  
High Resolution ◽  
Kinetic Energy ◽  
Horizontal Velocity ◽  
Energy Cascade ◽  
Two Dimensional ◽  
Inverse Energy Cascade ◽  
Wide Range ◽  
Geostrophic Turbulence ◽  
Decaying Turbulence ◽  
Enstrophy Cascade

High-resolution simulations of forced quasi-geostrophic (QG) turbulence reveal that Charney isotropy develops under a wide range of conditions, and constitutes a preferred state also in β-plane and freely decaying turbulence. There is a clear analogy between two-dimensional and QG turbulence, with a direct enstrophy cascade that is governed by the prediction of Kraichnan (J. Fluid Mech., vol. 47, 1971, p. 525) and an inverse energy cascade following the classic k−5/3 scaling. Furthermore, we find that Charney's prediction of equipartition between the potential and kinetic energy in each of the two horizontal velocity components is approximately fulfilled in the inertial ranges.

scholarly journals Vorticity Statistics in the Two-Dimensional Enstrophy Cascade

1999 ◽  
Vol 83 (17) ◽  
pp. 3418-3421 ◽  
Author(s):  
Jérôme Paret ◽  
Marie-Caroline Jullien ◽  
Patrick Tabeling
Keyword(s):  
Two Dimensional ◽  
Enstrophy Cascade

scholarly journals The effect of asymmetric large-scale dissipation on energy and potential enstrophy injection in two-layer quasi-geostrophic turbulence

2012 ◽  
Vol 694 ◽  
pp. 493-523 ◽  
Author(s):  
Eleftherios Gkioulekas
Keyword(s):  
Large Scale ◽  
Bottom Layer ◽  
Two Dimensional ◽  
Interlayer Interaction ◽  
Open Questions ◽  
Small Scales ◽  
Scale Range ◽  
Geostrophic Turbulence ◽  
Enstrophy Cascade ◽  
Potential Enstrophy

AbstractIn the Nastrom–Gage spectrum of atmospheric turbulence, we observe a${k}^{\ensuremath{-} 3} $energy spectrum that transitions into a${k}^{\ensuremath{-} 5/ 3} $spectrum, with increasing wavenumber$k$. The transition occurs near a transition wavenumber${k}_{t} $, located near the Rossby deformation wavenumber${k}_{R} $. The Tung–Orlando theory interprets this spectrum as a double downscale cascade of potential enstrophy and energy, from large scales to small scales, in which the downscale potential enstrophy cascade coexists with the downscale energy cascade over the same length scale range. We show that, in a temperature-forced two-layer quasi-geostrophic model, the rates with which potential enstrophy and energy are injected place the transition wavenumber${k}_{t} $near${k}_{R} $. We also show that, if the potential energy dominates the kinetic energy in the forcing range, then the Ekman term suppresses the upscale cascading potential enstrophy more than it suppresses the upscale cascading energy, a behaviour contrary to what occurs in two-dimensional turbulence. As a result, the ratio$\eta / \varepsilon $of injected potential enstrophy over injected energy, in the downscale direction, decreases, thereby tending to decrease the transition wavenumber${k}_{t} $further. Using a random Gaussian forcing model, we reach the same conclusion, under the modelling assumption that the asymmetric Ekman term predominantly suppresses the bottom layer forcing, thereby disregarding a possible entanglement between the Ekman term and the nonlinear interlayer interaction. Based on these results, we argue that the Tung–Orlando theory can account for the approximate coincidence between${k}_{t} $and${k}_{R} $. We also identify certain open questions that require further investigation via numerical simulations.

Linear Stability Analysis of LPT Rotor Packets: Part I — Methodology and Two-Dimensional Results

2004 ◽  
Author(s):  
Roque Corral ◽  
Carlos Lopez ◽  
Carlos Vasco
Keyword(s):  
Stability Analysis ◽  
Physical Mechanism ◽  
Point Of View ◽  
Two Dimensional ◽  
Aerodynamic Damping ◽  
Low Pressure Turbine ◽  
Damping Characteristics ◽  
Stabilizing Effect ◽  
The One ◽  
Tip Shroud

Part I of this paper compares the aerodynamic damping of a modern LPT airfoil to the one obtained when pairs of blades are forced to vibrate as a rigid body to mimic the dynamics of welded-pair assemblies. The stabilizing effect of this configuration is shown by means of two-dimensional linear simulations using the Panovsky and Kielb (PK) method. A plausible physical mechanism for the added damping of the welded-pair configuration is outlined. The modal characteristics of three bladed-disc models that differ just in the boundary conditions of the tip-shroud are also compared. These models are representatives of cantilever, interlock and welded-pair designs of low pressure turbine (LPT) rotating parts. The differences in terms of frequency and mode-shape of the three models are sketched. Finally their relative merits from a flutter point of view are discussed making use solely of the two-dimensional aerodynamic damping characteristics.

scholarly journals Enstrophy Cascade in Decaying Two-Dimensional Quantum Turbulence

2017 ◽  
Vol 119 (18) ◽  
Author(s):  
Matthew T. Reeves ◽  
Thomas P. Billam ◽  
Xiaoquan Yu ◽  
Ashton S. Bradley
Keyword(s):  
Quantum Turbulence ◽  
Two Dimensional ◽  
Enstrophy Cascade
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