Self-consistent theory of turbulent transport in the solar tachocline
نویسنده
چکیده
Aims. To understand the fundamental physical processes important for the evolution of solar rotation and distribution of chemical species, we provide theoretical predictions for particle mixing and momentum transport in the stably stratified tachocline. Methods. By envisioning that turbulence is driven in the tachocline, we compute the amplitude of turbulent flow, turbulent particle diffusivities, and eddy viscosity, by incorporating the effect of a strong radial differential rotation and stable stratification. We identify the different roles that the shear flow and stable stratification play in turbulence regulation and transport. Results. Particle transport is found to be severely quenched due to stable stratification as well as radial differential rotation, especially in the radial direction with an effectively more efficient horizontal transport. The eddy viscosity is shown to become negative for parameter values typical of the tachocline, suggesting that turbulence in the stably stratified tachocline leads to a non-uniform radial differential rotation. Similar results also hold in the radiative interiors of stars, in general.
منابع مشابه
Self-consistent theory of turbulent transport in the solar tachocline II. Tachocline confinement
Aims. We provide a consistent theory of the tachocline confinement (or anisotropic momentum transport) within an hydrodynamical turbulence model. The goal is to explain helioseismological data, which show that the solar tachocline thickness is at most 5% of the solar radius, despite the fact that, due to radiative spreading, this transition layer should have thickened to a much more significant...
متن کاملOn a long-term dynamics of the magnetised solar tachocline
Aims. We investigate the confinement and long-term dynamics of the magnetised solar tachocline. Methods. Starting from first principles, we derive the values of turbulent transport coefficients in the magnetised solar tachocline and then explore the implications for the confinement and long-term dynamics of the tachocline. Results. For reasonable parameter values, the turbulent eddy viscosity i...
متن کاملSeismic Observation of Solar Tachocline
Helioseismology has established the existence of a layer of strong gradients of angular velocity at the base of the solar convection zone. This layer (`tachocline') separates the convection zone exhibiting a strong latitudinal differential rotation from the radiative interior that rotates almost rigidly. Turbulence generated in the tachocline is likely to mix material in the upper radiative zon...
متن کاملAngular Momentum Transport by Gravity waves in the Solar Interior
We present self-consistent numerical simulations of the sun’s convection zone and radiative interior using a two-dimensional model of its equatorial plane. The background reference state is a one-dimensional solar structure model. Turbulent convection in the outer convection zone continually excites gravity waves which propagate throughout the stable radiative interior and deposit their angular...
متن کاملEffect of rotation on the tachoclinic transport
Aims. We study the effect of rotation on sheared turbulence, due to differential rotation in the solar tachocline. Methods. By solving quasi-linear equations for the fluctuating fields, we derive turbulence amplitude and turbulent transport coefficients (turbulent viscosity and diffusivity), taking into account the effects of shear and rotation on turbulence. We focus on the tachocline regions ...
متن کامل