Transport of angular momentum and chemical species by anisotropic mixing in stellar radiative interiors

Kitchatinov, L. L.; Brandenburg, Axel

doi:10.1002/asna.201211648

Cited by 12 publications

(17 citation statements)

References 22 publications

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“…Finally, if one considers the choice τ = 1/N, even though Kitchatinov & Brandenburg (2012) assumed it was not the case, one obtains an anisotropy which is consistent with the work by Billant & Chomaz (2001). However, 1/N characterizes the stratification that inhibits the turbulence while the nonlinear timescale should rather be given by the process that drives the turbulence, i.e.…”

Section: Characterization Of the Turbulent Timescalesupporting

confidence: 65%

“…which show no explicit dependence on the shear number S * . Therefore, we recover in the case of a radial differential rotation the expressions found by Kitchatinov & Brandenburg (2012) in the case of solid-body rotation.…”

Section: Spectral Formalismsupporting

confidence: 59%

“…Moreover, following Kitchatinov & Brandenburg (2012), a relaxation approximation is used to get rid of non-linear terms. It consists in assuming that the fluid tends to reach a steady state with a typical time scale τ.…”

Section: Spectral Formalismmentioning

confidence: 99%

“…On the other hand, theoretical works (e.g. Billant & Chomaz 2001;Kitchatinov & Brandenburg 2012) and numerical simulations (Waite & Bartello 2006;Kitchatinov & Brandenburg 2012) in fundamental and astrophysical fluid dynamics have been devoted to characterize key properties of anisotropic turbulent flows in rotating stably stratified media, such as velocities and length scales in the vertical and horizontal directions. This is a good motivation to also consider the horizontal transport induced by 3D turbulent motions sustained by the instability of the radial differential rotation, which has been ignored until now.…”

Section: Introductionmentioning

confidence: 99%

“…In Sect. 2, we generalize the spectral model introduced by Kitchatinov & Brandenburg (2012) to study the anisotropy of turbulent flows in differentially rotating stably stratified layers and we derive scaling laws allowing us to establish our new prescriptions. In Sect.…”

Section: Introductionmentioning

confidence: 99%

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Anisotropic turbulent transport in stably stratified rotating stellar radiation zones

Mathis

Prat

Amard

et al. 2018

A&A

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Context. Rotation is one of the key physical mechanisms that deeply impact the evolution of stars. Helio-and asteroseismology reveal a strong extraction of angular momentum from stellar radiation zones over the whole Hertzsprung-Russell diagram. Aims. Turbulent transport in differentially rotating stably stratified stellar radiation zones should be carefully modeled and its strength evaluated. Stratification and rotation imply that this turbulent transport is anisotropic. Only phenomenological prescriptions have been proposed for the transport in the horizontal direction, which however constitutes a cornerstone in current theoretical formalisms for stellar hydrodynamics in evolution codes. We aim at improving its modeling. Methods. We derive a new theoretical prescription for the anisotropy of the turbulent transport in radiation zones using a spectral formalism for turbulence that takes simultaneously stable stratification, rotation, and a radial shear into account. Then, the horizontal turbulent transport resulting from 3D turbulent motions sustained by the instability of the radial differential rotation is derived. We implement this framework in the stellar evolution code STAREVOL and quantify its impact on the rotational and structural evolution of solar metallicity low-mass stars from the pre-main-sequence to the red giant branch. Results. The anisotropy of the turbulent transport scales as N 4 τ 2 / 2Ω 2 , N and Ω being the buoyancy and rotation frequencies respectively and τ a time characterizing the source of turbulence. This leads to a horizontal turbulent transport of similar strength in average that those obtained with previously proposed prescriptions even if it can be locally larger below the convective envelope. Hence the models computed with the new formalism still build up too steep internal rotation gradients compared to helioseismic and asteroseismic constraints. As a consequence, a complementary transport mechanism like internal gravity waves or magnetic fields is still needed to explain the observed strong transport of angular momentum along stellar evolution. Conclusions. The new prescription links for the first time the anisotropy of the turbulent transport in radiation zones to their stratification and rotation. This constitutes an important theoretical progress and demonstrates how turbulent closure models should be improved to get firm conclusions on the potential importance of other processes that transport angular momentum and chemicals inside stars along their evolution.

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Section: Characterization Of the Turbulent Timescalesupporting

confidence: 65%

Section: Spectral Formalismsupporting

confidence: 59%

Section: Spectral Formalismmentioning

confidence: 99%