Equilibrium Problem in a Rotating Convection Zone

1976 ◽  
pp. 297-297
Author(s):  
Yu. V. Vandakurov
Keyword(s):  
Equilibrium Problem ◽  
Convection Zone ◽  
Rotating Convection

scholarly journals Diamagnetic pumping in a rotating convection zone

2016 ◽  
Vol 58 (8) ◽  
pp. 1554-1559 ◽  
Author(s):  
L.L. Kitchatinov ◽  
A.A. Nepomnyashchikh
Keyword(s):  
Convection Zone ◽  
Rotating Convection

scholarly journals Equilibrium Problem in a Rotating Convection Zone

1976 ◽  
Vol 71 ◽  
pp. 297-297
Author(s):  
YU. V. Vandakurov
Keyword(s):  
Equilibrium Problem ◽  
Differential Rotation ◽  
Convection Zone ◽  
Turbulent Viscosity ◽  
Nonlinear Effects ◽  
Viscous Force ◽  
Small Scale ◽  
Slow Rotation ◽  
Field Reversal ◽  
Coefficient Of Viscosity

Taking into account effects produced by the convective motions, the equilibrium problem for a rotating star becomes greatly complicated. We consider this problem for the case of slow rotation in the following approximations.We treat the convection zone as a medium with turbulent viscosity and turbulent thermal conductivity. However, we take into account the nonlinear effects produced by the most rapidly growing perturbations. The corresponding nonlinear terms are calculated by using the solution of linear perturbed equations. Each independent convective mode is supposed to have initially the same amount of kinetic energy.In the limit of small turbulent viscosity, we show that unstable convective perturbations produce a mean azimuthal force due to which rigid rotation appears not to be in the equilibrium. For the case of small-scale perturbations and latitudinal differential rotation, this force is analogous to the viscous force, but the coefficient of viscosity is negative.We suggest that such a force maintains the differential rotation of the solar convection zone. Note that in the case under consideration the latitudinal dependence of the solar heat flux is small. However, difficulties arise due to different conditions at different depths in the convection zone. In this connection, a hypothesis is put forward that magnetic fields are also necessary to get balance in full. A model of the solar cycle is discussed which is similar in some respects to the well-known Babcock model. We propose, however, that the field reversal takes place in the lower layers of that zone where fields are intensified.

Equilibrium problems in a rotating convection zone

Solar Physics ◽  
1975 ◽  
Vol 45 (2) ◽  
pp. 501-520 ◽  
Author(s):  
Yu. V. Vandakurov
Keyword(s):  
Convection Zone ◽  
Equilibrium Problems ◽  
Rotating Convection

Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven Turbulence, and Solar Dynamo

2000 ◽  
Vol 179 ◽  
pp. 387-388
Author(s):  
Gaetano Belvedere ◽  
V. V. Pipin ◽  
G. Rüdiger
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Convection Zone ◽  
Solar Surface ◽  
Momentum Transport ◽  
Angular Momentum Transport ◽  
Magnetic Buoyancy ◽  
Alpha Effect ◽  
Current Helicity

Extended AbstractRecent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg & Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg & Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).

Solar Internal Rotation and Dynamo Waves: A Two-Dimensional Asymptotic Solution in the Convection Zone

2000 ◽  
Vol 179 ◽  
pp. 379-380
Author(s):  
Gaetano Belvedere ◽  
Kirill Kuzanyan ◽  
Dmitry Sokoloff
Keyword(s):  
Magnetic Field ◽  
Asymptotic Solution ◽  
Internal Rotation ◽  
Convection Zone ◽  
General Idea ◽  
Dynamo Model ◽  
Axially Symmetric ◽  
Dynamo Action ◽  
Regeneration Rate ◽  
Dynamo Waves

Extended abstractHere we outline how asymptotic models may contribute to the investigation of mean field dynamos applied to the solar convective zone. We calculate here a spatial 2-D structure of the mean magnetic field, adopting real profiles of the solar internal rotation (the Ω-effect) and an extended prescription of the turbulent α-effect. In our model assumptions we do not prescribe any meridional flow that might seriously affect the resulting generated magnetic fields. We do not assume apriori any region or layer as a preferred site for the dynamo action (such as the overshoot zone), but the location of the α- and Ω-effects results in the propagation of dynamo waves deep in the convection zone. We consider an axially symmetric magnetic field dynamo model in a differentially rotating spherical shell. The main assumption, when using asymptotic WKB methods, is that the absolute value of the dynamo number (regeneration rate) |D| is large, i.e., the spatial scale of the solution is small. Following the general idea of an asymptotic solution for dynamo waves (e.g., Kuzanyan & Sokoloff 1995), we search for a solution in the form of a power series with respect to the small parameter |D|–1/3(short wavelength scale). This solution is of the order of magnitude of exp(i|D|1/3S), where S is a scalar function of position.

Meridional Circulation, Turbulence, and Diffusion Processes in Stars

1976 ◽  
Vol 32 ◽  
pp. 109-116 ◽  
Author(s):  
S. Vauclair
Keyword(s):  
Convection Zone ◽  
Diffusion Processes ◽  
Meridional Circulation ◽  
Diffusion Time ◽  
Work In Progress ◽  
First Results ◽  
Stellar Envelopes ◽  
And Diffusion ◽  
Turbulence And Diffusion ◽  
Hr Diagram

This paper gives the first results of a work in progress, in collaboration with G. Michaud and G. Vauclair. It is a first attempt to compute the effects of meridional circulation and turbulence on diffusion processes in stellar envelopes. Computations have been made for a 2 Mʘstar, which lies in the Am - δ Scuti region of the HR diagram.Let us recall that in Am stars diffusion cannot occur between the two outer convection zones, contrary to what was assumed by Watson (1970, 1971) and Smith (1971), since they are linked by overshooting (Latour, 1972; Toomre et al., 1975). But diffusion may occur at the bottom of the second convection zone. According to Vauclair et al. (1974), the second convection zone, due to He II ionization, disappears after a time equal to the helium diffusion time, and then diffusion may happen at the bottom of the first convection zone, so that the arguments by Watson and Smith are preserved.

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