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Stably-stratified layers may be present at the top of the electrically-conducting fluid layers of many planets either because the temperature gradient is locally subadiabatic or because a stable composition gradient is maintained by the…

Earth and Planetary Astrophysics · Physics 2022-11-08 Celine Guervilly

We perform three-dimensional hydrodynamic simulations of two idealized regimes of stellar convection: a cooling-driven model (Model C) and an entropy-gradient-driven model (Model S). The two regimes exhibit striking contrasts: while Model S…

Solar and Stellar Astrophysics · Physics 2025-11-18 Youhei Masada , Tomoya Takiwaki , Nobumitsu Yoko

The dynamics of convecting fluids in rotating spherical shells is governed at Prandtl numbers of the order unity by the interaction between differential rotation and roll-like convection eddies. While the differential rotation is driven by…

Fluid Dynamics · Physics 2009-05-25 F. H. Busse , R. D. Simitev

The sedimentation of a spherical particle in an elastoviscoplastic fluid in proximity of a flat wall is investigated by direct numerical simulations. The governing equations under inertialess conditions are solved by the finite element…

Fluid Dynamics · Physics 2023-02-10 Alie Abbasi Yazdi , Gaetano D'Avino

To understand how spherical geometry influences the dynamics of gravity-driven subduction of oceanic lithosphere on Earth, we study a simple model of a thin and dense axisymmetric shell of thickness $h$ and viscosity $\eta_1$ sinking in a…

Fluid Dynamics · Physics 2021-11-10 Alexander Chamolly , Neil M. Ribe

We present two continuum models A and B to study the convective instability of granular materials subjected to vibrations. We carry out the linear stability analysis for model A and uncover the instability mechanism as a supercritical…

Materials Science · Physics 2008-02-03 Hisao Hayakawa , Daniel C. Hong

Molecular dynamics simulation has been used to model pattern formation in three-dimensional Rayleigh--Benard convection at the discrete-particle level. Two examples are considered, one in which an almost perfect array of hexagonally-shaped…

Other Condensed Matter · Physics 2009-11-11 D. C. Rapaport

The flow of incompressible fluids through porous media plays a crucial role in many technological applications such as enhanced oil recovery and geological carbon-dioxide sequestration. The flow within numerous natural and synthetic porous…

Computational Engineering, Finance, and Science · Computer Science 2018-05-23 S. H. S. Joodat , K. B. Nakshatrala , R. Ballarini

A three-dimensional finite-difference solver has been developed and implemented for Boussinesq convection in a spherical shell. The solver transforms any complex curvilinear domain into an equivalent Cartesian domain using Jacobi…

Computational Physics · Physics 2023-05-30 Souvik Naskar , Karu Chongsiripinyo , Anikesh Pal , Akshay Jananan

As we approach solar convection simulations that seek to model the interaction of small-scale granulation and supergranulation and even larger scales of convection within the near-surface shear layer (NSSL), the treatment of the boundary…

Solar and Stellar Astrophysics · Physics 2015-05-20 Kyle Augustson , Mark Rast , Regner Trampedach , Juri Toomre

Despite all advances in multi-dimensional hydrodynamics, investigations of stellar evolution and stellar pulsations still depend on one-dimensional computations. The present work devises an alternative to the mixing length theory or…

Astrophysics · Physics 2009-11-13 Alexander Stoekl

We perform three-dimensional direct numerical simulations of surface-driven convection near the temperature of maximum density $\tilde T_{md}$. A dynamic surface boundary condition couples heat flux through the surface to the induced…

Atmospheric and Oceanic Physics · Physics 2024-05-08 Jason Olsthoorn

The problem of steady mixed convection boundary-layer flow on a cooled vertical permeable circular cylinder embedded in a fluid-saturated porous medium is studied. Here, we evaluate the flow and heat transfer characteristics numerically for…

Fluid Dynamics · Physics 2018-03-19 Jian-Jun Shu , Qi-Wen Wang , Ioan Pop

The asymptotic behavior of a class of stochastic reaction-diffusion-advection equations in the plane is studied. We show that as the divergence-free advection term becomes larger and larger, the solutions of such equations converge to the…

Probability · Mathematics 2020-08-10 Sandra Cerrai , Guangyu Xi

Pseudo-parabolic equations have been used to model unsaturated fluid flow in porous media. In this paper it is shown how a pseudo-parabolic equation can be upscaled when using a spatio-temporal decomposition employed in the…

Analysis of PDEs · Mathematics 2018-10-09 Arthur J. Vromans , Fons van de Ven , Adrian Muntean

Remarkably persistent mixing and non-mixing regions (islands) are observed to coexist in a three-dimensional dynamical system where randomness is expected. The track of an x-ray opaque particle in a spherical shell half-filled with dry…

Soft Condensed Matter · Physics 2018-09-05 Zafir Zaman , Mengqi Yu , Paul P. Park , Julio M. Ottino , Richard M. Lueptow , Paul B. Umbanhowar

When particles settle through a stable temperature or salinity gradient they can drive an instability known as sedimentary fingering convection. This phenomenon is thought to occur beneath sediment-rich river plumes in lakes and oceans, in…

Fluid Dynamics · Physics 2017-04-05 J. F. Reali , P. Garaud , A. Alsinan , E. Meiburg

We consider dynamo action driven by three-dimensional rotating anelastic convection in a spherical shell. Motivated by the behaviour of the solar dynamo, we examine the interaction of hydromagnetic modes with different symmetries and…

Solar and Stellar Astrophysics · Physics 2016-07-06 Raphaël Raynaud , Steven M. Tobias

We present the results of 3--D simulations of core convection within A-type stars of 2 solar masses, at a range of rotation rates. We consider the inner 30% by radius of such stars, thereby encompassing the convective core and some of the…

Astrophysics · Physics 2008-11-26 Matthew Browning , Allan Sacha Brun , Juri Toomre

Convection of an internally heated fluid, confined between top and bottom plates of equal temperature, is studied by direct numerical simulation in two and three dimensions. The unstably stratified upper region drives convection that…

Fluid Dynamics · Physics 2016-06-30 David Goluskin , Erwin P. van der Poel