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Double-diffusive convection refers to mixing where the effects of thermal and composition gradients compete to determine the stability of a fluid. In addition to the familiar fast convective instability, such fluids exhibit the slow, direct…

Astrophysics · Physics 2015-06-24 Scott A. Grossman , Ronald E. Taam

A ubiquitous arrangement in nature is a free-flowing fluid coupled to a porous medium, for example a river or lake lying above a porous bed. Depending on the environmental conditions, thermal convection can occur and may be confined to the…

Fluid Dynamics · Physics 2022-12-21 Matthew McCurdy , Nicholas J. Moore , Xiaoming Wang

A simplified model for stellar and planetary convection is derived for the magnitude of the rms velocity, degree of superadiabaticity, and characteristic length scale with Rossby number as well as with thermal and viscous diffusivities.…

Solar and Stellar Astrophysics · Physics 2018-11-13 Kyle Augustson , Stéphane Mathis

The solar convection zone rotates differentially, with its equatorial region rotating more rapidly than the polar regions. This form of differential rotation, also observed in many other low-mass stars, is understood to arise when Coriolis…

Solar and Stellar Astrophysics · Physics 2022-10-26 Maria E. Camisassa , Nicholas A. Featherstone

We assess experimentally the scaling laws that characterize the mixing region produced by the Rayleigh-Taylor instability in a confined porous medium. In particular, we wish to assess experimentally the existence of a superlinear scaling…

Fluid Dynamics · Physics 2024-08-02 Marco De Paoli , Diego Perissutti , Cristian Marchioli , Alfredo Soldati

Convectively driven dynamos with rotation generating magnetic fields on scales large compared with the scale of the turbulent eddies are being reviewed. It is argued that such fields can be understood as the result of an alpha effect.…

Solar and Stellar Astrophysics · Physics 2011-08-19 A. Brandenburg , P. J. Käpylä , M. J. Korpi

Increasing evidence is becoming available about not only the surface differential rotation of rapidly rotating cool stars but, in a small number of cases, also about temporal variations, which possibly are analogous to the solar torsional…

Astrophysics · Physics 2009-11-10 E. Covas , D. Moss , R. Tavakol

A monomodal model for stellar and planetary convection is derived for the magnitude of the rms velocity, degree of superadiabaticity, and characteristic length scale as a function of rotation rate as well as with thermal and viscous…

Solar and Stellar Astrophysics · Physics 2019-04-03 Kyle C. Augustson , Stéphane Mathis

The atmospheric convective boundary layer (CBL) consists of three basic parts: (i) the surface layer unstably stratified and dominated by small-scale turbulence of very complex nature; (ii) the CBL core dominated by the energy-, momentum-…

Fluid Dynamics · Physics 2024-04-19 I. Rogachevskii , N. Kleeorin

The use of machine learning to represent subgrid-scale (SGS) dynamics is now well established in weather forecasting and climate modelling. Recent advances have demonstrated that SGS models trained via ``online'' end-to-end learning --…

Fluid Dynamics · Physics 2025-11-19 Hugo Frezat , Thomas Gastine , Alexandre Fournier

Using a thin flux tube model in a rotating spherical shell of turbulent, solar-like convective flows, we find that the distribution of emerging flux tubes in our simulation is inhomogeneous in longitude, with properties similar to those of…

Solar and Stellar Astrophysics · Physics 2015-06-15 Maria A. Weber , Yuhong Fan , Mark S. Miesch

The outer areas of Jupiter and Saturn have multiple zonal winds, reaching the high latitudes, that penetrate deep into the planets' interiors, as suggested by gravity measurements. These characteristics are replicable in numerical…

Earth and Planetary Astrophysics · Physics 2024-02-02 Paula N. Wulff , Ulrich R. Christensen , Wieland Dietrich , Johannes Wicht

How turbulent convective fluctuations organise to form large-scale structures in planetary atmospheres remains a question that eludes quantitative answers. The assumption that this process is the result of an inverse cascade was suggested…

Protoplanetary disks are prone to several hydrodynamic instabilities. One candidate, Convective Overstability (COS), can drive radial semi-convection that may influence dust dynamics and planetesimal formation. However, the COS has…

Earth and Planetary Astrophysics · Physics 2024-05-12 Marius Lehmann , Min-Kai Lin

We examine the linear behavior of three-dimensional Lagrangian displacements in a stratified, shearing background. The isentropic and iso-rotation surfaces of the equilibrium flow are assumed to be axisymmetric, but otherwise fully…

Solar and Stellar Astrophysics · Physics 2015-06-05 Steven A. Balbus , Emmanuel Schaan

We propose a new self-consistent dynamo mechanism for the generation of large-scale magnetic fields in natural objects. Recent computational studies have described the formation of large-scale vortices (LSVs) in rotating turbulent…

Fluid Dynamics · Physics 2015-06-24 Celine Guervilly , David W. Hughes , Chris A. Jones

Direct numerical simulations of fully-developed turbulent channel flows with wavy walls are undertaken. The wavy walls, skewed with respect to the mean flow direction, are introduced as a means of emulating a Spatial Stokes Layer (SSL)…

Fluid Dynamics · Physics 2018-03-05 Sacha Ghebali , Sergei I. Chernyshenko , Michael A. Leschziner

We present a series of 3-D nonlinear simulations of solar-like convection, carried out using the Anelastic Spherical Harmonic (ASH) code, that are designed to isolate those processes that drive and shape meridional circulations within…

Solar and Stellar Astrophysics · Physics 2015-05-20 Nicholas A. Featherstone , Mark S. Miesch

Gravitational coupling between protoplanetary discs and planets embedded in them leads to the emergence of spiral density waves, which evolve into shocks as they propagate through the disc. We explore the performance of a semi-analytical…

Earth and Planetary Astrophysics · Physics 2021-09-22 Nicolas P. Cimerman , Roman R. Rafikov

Results of realistic simulations of solar surface convection on the scale of supergranules (96 Mm wide by 20 Mm deep) are presented. The simulations cover only 10% of the geometric depth of the solar convection zone, but half its pressure…

Astrophysics · Physics 2008-11-05 R. F. Stein , A. Nordlund , D. Georgobiani , D. Benson , W. Schaffenberger