On the generation of flux tube waves in stellar convection zones. I - Longitudinal tube waves driven by external turbulence

1989 ◽  
Vol 337 ◽  
pp. 470 ◽  
Author(s):  
Z. E. Musielak ◽  
R. Rosner ◽  
P. Ulmschneider
Keyword(s):  
Flux Tube ◽  
Stellar Convection ◽  
External Turbulence

scholarly journals Linking Thin Flux Tube MHD Models to Apparent Stellar Surface Activity

2004 ◽  
Vol 219 ◽  
pp. 546-551
Author(s):  
T. Granzer ◽  
K. G. Strassmeier
Keyword(s):  
Magnetic Flux ◽  
Surface Activity ◽  
Flux Tube ◽  
Convection Zone ◽  
Active Regions ◽  
Similar Model ◽  
Flux Tubes ◽  
Stellar Convection ◽  
Magnetic Flux Tubes ◽  
Spot Formation

We model thin magnetic flux tubes as they rise from the bottom of a stellar convection zone to the photosphere. On emergence they form active regions, i.e. star spots. This model was very successfully applied to the solar case, where the simulations where in agreement with the butterfly diagram, Joy's law, and Hale's law. We propose the use of a similar model to describe stellar activity in the more extreme form found on active stars. A comparison between Doppler-images of well-observed pre-MS stars and a theoretically derived probability of star-spot formation as a function of latitude is presented.

On the Generation of Flux‐Tube Waves in Stellar Convection Zones. III. Longitudinal Tube Wave‐Energy Spectra and Fluxes for Late‐Type Stars

2000 ◽  
Vol 541 (1) ◽  
pp. 410-417 ◽  
Author(s):  
Z. E. Musielak ◽  
R. Rosner ◽  
P. Ulmschneider
Keyword(s):  
Flux Tube ◽  
Wave Energy ◽  
Energy Spectra ◽  
Late Type ◽  
Stellar Convection ◽  
Tube Wave

On the Generation of Flux‐Tube Waves in Stellar Convection Zones. IV. Longitudinal Wave Energy Spectra and Fluxes for Stars with Nonsolar Metallicities

2002 ◽  
Vol 573 (1) ◽  
pp. 418-424 ◽  
Author(s):  
Z. E. Musielak ◽  
R. Rosner ◽  
P. Ulmschneider
Keyword(s):  
Longitudinal Wave ◽  
Flux Tube ◽  
Wave Energy ◽  
Energy Spectra ◽  
Stellar Convection

On the Generation of Flux-Tube Waves in Stellar Convection Zones. II. Improved Treatment of Longitudinal Tube Wave Generation

1995 ◽  
Vol 448 ◽  
pp. 865 ◽  
Author(s):  
Z. E. Musielak ◽  
R. Rosner ◽  
H. P. Gail ◽  
P. Ulmschneider
Keyword(s):  
Flux Tube ◽  
Wave Generation ◽  
Stellar Convection ◽  
Tube Wave

scholarly journals Effective String Description of the Confining Flux Tube at Finite Temperature

Universe ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 170
Author(s):  
Michele Caselle
Keyword(s):  
Flux Tube ◽  
Dimensional Reduction ◽  
Conformal Invariance ◽  
Finite Temperature ◽  
Gauge Theories ◽  
Linear Increase ◽  
General Introduction ◽  
Interquark Potential ◽  
Effective String Theory ◽  
Good Agreement

In this review, after a general introduction to the effective string theory (EST) description of confinement in pure gauge theories, we discuss the behaviour of EST as the temperature is increased. We show that, as the deconfinement point is approached from below, several universal features of confining gauge theories, like the ratio Tc/σ0, the linear increase of the squared width of the flux tube with the interquark distance, or the temperature dependence of the interquark potential, can be accurately predicted by the effective string. Moreover, in the vicinity of the deconfinement point the EST behaviour turns out to be in good agreement with what was predicted by conformal invariance or by dimensional reduction, thus further supporting the validity of an EST approach to confinement.

scholarly journals Heat Transfer in Highly Turbulent Separated Flows: A Review

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1005
Author(s):  
Viktor I. Terekhov
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Separated Flow ◽  
Separated Flows ◽  
Turbulence Characteristic ◽  
Wall Jets ◽  
Average Heat ◽  
Free Stream Turbulence ◽  
External Turbulence ◽  
Near Wall

The study of flows with a high degree of turbulence in boundary layers, near-wall jets, gas curtains, separated flows behind various obstacles, as well as during combustion is of great importance for increasing energy efficiency of the flow around various elements in the ducts of gas-dynamic installations. This paper gives some general characteristics of experimental work on the study of friction and heat transfer on a smooth surface, in near-wall jets, and gas curtains under conditions of increased free-stream turbulence. Taking into account the significant effect of high external turbulence on dynamics and heat transfer of separated flows, a similar effect on the flow behind various obstacles is analyzed. First of all, the classical cases of flow separation behind a single backward-facing step and a rib are considered. Then, more complex cases of the flow around a rib oriented at different angles to the flow are analyzed, as well as a system of ribs and a transverse trench with straight and inclined walls in a turbulent flow around them. The features of separated flow in a turbulized stream around a cylinder, leading to an increase in the width of the vortex wake, frequency of vortex separation, and increase in the average heat transfer coefficient are analyzed. The experimental results of the author are compared with data of other researchers. The structure of separated flow at high turbulence—characteristic dimensions of the separation region, parameters of the mixing layer, and pressure distribution—are compared with the conditions of low-turbulent flow. Much attention is paid to thermal characteristics: temperature profiles across the shear layer, temperature distributions over the surface, and local and average heat transfer coefficients. It is shown that external turbulence has a much stronger effect on the separated flow than on the boundary layer on a flat surface. For separated flows, its intensifying effect on heat transfer is more pronounced behind a rib than behind a step. The factor of heat transfer intensification by external turbulence is most pronounced in the transverse cavity and in the system of ribs.

scholarly journals Incompressible magnetohydrodynamic modes in the thin magnetically twisted flux tube

2017 ◽  
Vol 604 ◽  
pp. A62 ◽  
Author(s):  
O. K. Cheremnykh ◽  
V. Fedun ◽  
A. N. Kryshtal ◽  
G. Verth
Keyword(s):  
Flux Tube

scholarly journals Possible Global Magneto-Fluid Structure of the Stellar Convection Zone

2006 ◽  
Vol 58 (3) ◽  
pp. 605-616 ◽  
Author(s):  
Sanae I. Itoh ◽  
Kimitaka Itoh ◽  
Patrick H. Diamond ◽  
Akira Yoshizawa
Keyword(s):  
Convection Zone ◽  
Fluid Structure ◽  
Stellar Convection

Connecting a Star’s Convection Zone with its Corona

1995 ◽  
Vol 12 (2) ◽  
pp. 180-185 ◽  
Author(s):  
D. J. Galloway ◽  
C. A. Jones
Keyword(s):  
Magnetic Field ◽  
Convection Zone ◽  
Flux Rope ◽  
Field System ◽  
Stellar Convection ◽  
Coronal Activity ◽  
Flux Concentration ◽  
Global Understanding ◽  
The Magnetic Field

AbstractThis paper discusses problems which have as their uniting theme the need to understand the coupling between a stellar convection zone and a magnetically dominated corona above it. Interest is concentrated on how the convection drives the atmosphere above, loading it with the currents that give rise to flares and other forms of coronal activity. The role of boundary conditions appears to be crucial, suggesting that a global understanding of the magnetic field system is necessary to explain what is observed in the corona. Calculations are presented which suggest that currents flowing up a flux rope return not in the immediate vicinity of the rope but rather in an alternative flux concentration located some distance away.

scholarly journals Temporary topological trapping and escape of charged particles in a flux tube as a cause of delay in time asymptotic transport

2007 ◽  
Vol 34 (17) ◽  
Author(s):  
P. Tooprakai ◽  
P. Chuychai ◽  
J. Minnie ◽  
D. Ruffolo ◽  
J. W. Bieber ◽  
...  
Keyword(s):  
Flux Tube ◽  
Charged Particles
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