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A simple model of nonlinear salt-finger convection in two dimensions is derived and studied. The model is valid in the limit of small solute to heat diffusivity ratio and large density ratio, which is relevant to both oceanographic and…

Fluid Dynamics · Physics 2017-03-13 Jin-Han Xie , Benjamin Miquel , Keith Julien , Edgar Knobloch

In this paper we carry out numerical analysis for a family of simplified gas transport models with hydrate formation and dissociation in subsurface, in equilibrium and non-equilibrium conditions. These models are adequate for simulation of…

Numerical Analysis · Mathematics 2021-03-18 Malgorzata Peszynska , Choah Shin

Standard 1D stellar evolution models do not correctly reproduce the structure of the outermost layers of stars with convective envelopes. This has been a long-standing problem in stellar modelling affecting both the predicted evolutionary…

The scale length over which convection mixes mass in a star can be calculated as the inverse of the vertical derivative of the unidirectional (up or down) mass flux. This is related to the mixing length in the mixing length theory of…

Solar and Stellar Astrophysics · Physics 2015-05-27 Regner Trampedach , Robert F. Stein

We present an energy-stable scheme for numerically approximating the governing equations for incompressible two-phase flows with different densities and dynamic viscosities for the two fluids. The proposed scheme employs a scalar-valued…

Computational Physics · Physics 2019-06-26 Z. Yang , S. Dong

Existing numerical models of the swash zone are relatively inflexible in dealing with sediment transport due to a high dependence of the deployed numerical schemes on empirical sediment transport relations. Moreover, these models are…

Atmospheric and Oceanic Physics · Physics 2015-09-28 Peng Hu , Wei Li , Zhiguo He , Thomas Pähtz , Zhiyuan Yue

We propose a novel Skew Gradient Embedding (SGE) framework for systematically reformulating thermodynamically consistent partial differential equation (PDE) models-capturing both reversible and irreversible processes-as generalized gradient…

Numerical Analysis · Mathematics 2025-09-24 Xuelong Gu , Qi Wang

We present numerical relativity simulations of cosmological scenarios in which the universe is smoothed and flattened by undergoing a phase of slow contraction and test their sensitivity to a wide range of initial conditions. Our numerical…

General Relativity and Quantum Cosmology · Physics 2020-08-14 Anna Ijjas , William G. Cook , Frans Pretorius , Paul J. Steinhardt , Elliot Y. Davies

Condensable species are crucial in shaping planetary climate. A wide range of planetary climate systems involve understanding non-dilute condensable substances and their influence on climate dynamics. There has been progress on large-scale…

Earth and Planetary Astrophysics · Physics 2021-12-22 Xianyu Tan , Maxence Lefevre , Raymond Pierrehumbert

High order algorithms have emerged in numerical astrophysics as a promising avenue to reduce truncation error (proportional to a power of the linear resolution $\Delta x$) with only a moderate increase to computational expense. Significant…

Instrumentation and Methods for Astrophysics · Physics 2025-02-27 Tomoyuki Hanawa , Patrick D. Mullen

We address here the discretization of the momentum convection operator for fluid flow simulations on 2D triangular and quadrangular meshes and 3D polyhedral meshes containing hexahedra, tetrahedra, prisms and pyramids. The finite volume…

Numerical Analysis · Mathematics 2022-09-15 Aubin Brunel , Raphaèle Herbin , Jean-Claude Latché

In the surface layers of late-type stars, stellar convection is manifested with its typical granulation pattern due to the presence of convective motions. The resulting photospheric up- and downflows leave imprints in the observed spectral…

Solar and Stellar Astrophysics · Physics 2014-05-30 Zazralt Magic , Martin Asplund

We present a new systematic way of setting up galactic gas disks based on the assumption of detailed hydrodynamic equilibrium. To do this, we need to specify the density distribution and the velocity field which supports the disk. We first…

Astrophysics of Galaxies · Physics 2015-05-18 Hsiang-Hsu Wang , Ralf S. Klessen , Cornelis P. Dullemond , Frank C. van den Bosch , Burkhard Fuchs

State-of-the-art one-dimensional (1D) stellar evolution codes rely on simplifying assumptions, such as mixing length theory, in order to describe superadiabatic convection. As a result, 1D stellar structure models do not correctly recover…

Solar and Stellar Astrophysics · Physics 2019-08-07 Andreas Christ Sølvsten Jørgensen , Achim Weiss

The He-shell flash convection in AGB stars is the site for the high-temperature component of the s-process in low- and intermediate mass giants, driven by the Ne22 neutron source. [...] The upper convection boundary plays a critical role…

Solar and Stellar Astrophysics · Physics 2009-01-23 Paul R. Woodward , David H. Porter , Falk Herwig , Marco Pignatari , Jagan Jayaraj , Pei-Hung Lin

When dealing with shallow water simulations, the velocity profile is often assumed to be constant along the vertical axis. However, since in many applications this is not the case, modeling errors can be significant. Hence, in this work, we…

Numerical Analysis · Mathematics 2025-01-15 C. Caballero-Cárdenas , I. Gómez-Bueno , A. del Grosso , J. Koellermeier , T. Morales de Luna

The spatial and temporal relationships between stellar age, kinematics, and chemistry are a fundamental tool for uncovering the physics driving galaxy formation and evolution. Observationally, these trends are derived using carefully…

Astrophysics of Galaxies · Physics 2022-10-26 M. S. Miranda , B. A. Macfarlane , B. K. Gibson

The interaction of magnetic fields and stratified convection was studied in the context of the solar and late type stellar dynamos by using numerical 3D MHD simulations. The topology of stratified asymmetric and over-turning convection…

Astrophysics · Physics 2007-05-23 Bertil Dorch , Aake Nordlund

We present a new massively parallel code for N-body and cosmological hydrodynamical simulations of modified gravity models. The code employs a multigrid-accelerated Newton-Gauss-Seidel relaxation solver on an adaptive mesh to efficiently…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Ewald Puchwein , Marco Baldi , Volker Springel

We introduce a new method to mitigate numerical diffusion in adaptive mesh refinement (AMR) simulations of cosmological galaxy formation, and study its impact on a simulated dwarf galaxy as part of the 'EDGE' project. The target galaxy has…