Title: Well-balanced treatment of gravity in astrophysical fluid dynamics simulations at low Mach numbers

Journal Article · · Astronomy and Astrophysics

We report accurate simulations of flows in stellar interiors are crucial to improving our understanding of stellar structure and evolution. Because the typically slow flows are merely tiny perturbations on top of a close balance between gravity and the pressure gradient, such simulations place heavy demands on numerical hydrodynamics schemes. We demonstrate how discretization errors on grids of reasonable size can lead to spurious flows orders of magnitude faster than the physical flow. Well-balanced numerical schemes can deal with this problem. Three such schemes were applied in the implicit, finite-volume SEVEN-LEAGUE HYDRO code in combination with a low-Mach-number numerical flux function. We compare how the schemes perform in four numerical experiments addressing some of the challenges imposed by typical problems in stellar hydrodynamics. We find that the α-β and deviation well-balancing methods can accurately maintain hydrostatic solutions provided that gravitational potential energy is included in the total energy balance. They accurately conserve minuscule entropy fluctuations advected in an isentropic stratification, which enables the methods to reproduce the expected scaling of convective flow speed with the heating rate. The deviation method also substantially increases accuracy of maintaining stationary orbital motions in a Keplerian disk on long timescales. The Cargo–LeRoux method fares substantially worse in our tests, although its simplicity may still offer some merits in certain situations. Overall, we find the well-balanced treatment of gravity in combination with low Mach number flux functions essential to reproducing correct physical solutions to challenging stellar slow-flow problems on affordable collocated grids.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
German Research Foundation (DFG); Klaus Tschira Foundation; USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
89233218CNA000001
OSTI ID:
1873334
Report Number(s):
LA-UR-21-21056
Journal Information:
Astronomy and Astrophysics, Journal Name: Astronomy and Astrophysics Vol. 652; ISSN 0004-6361
Publisher:
EDP SciencesCopyright Statement
Country of Publication:
United States
Language:
English

References (70)

A numerical model for the flooding and drying of irregular domains: ID AND 2D MODELLING OF SHALLOW WATER FLOW
  • Brufau, P.; Vázquez-Cendón, M. E.; García-Navarro, P.
  • International Journal for Numerical Methods in Fluids, Vol. 39, Issue 3 https://doi.org/10.1002/fld.285
journal May 2002
L 2 Roe: a low dissipation version of Roe's approximate Riemann solver for low Mach numbers : L journal September 2015
A well-balanced scheme to capture non-explicit steady states in the Euler equations with gravity: WELL-BALANCED SCHEME FOR THE EULER EQUATIONS WITH GRAVITY journal October 2015
Third‐ and fourth‐order well‐balanced schemes for the shallow water equations based on the CWENO reconstruction journal December 2018
A New Flux Splitting Scheme journal July 1993
A Sequel to AUSM: AUSM+ journal December 1996
Balancing Source Terms and Flux Gradients in High-Resolution Godunov Methods: The Quasi-Steady Wave-Propagation Algorithm journal October 1998
Transparent Boundary Conditions for MHD Simulations in Stratified Atmospheres journal August 2001
Physics, Formation and Evolution of Rotating Stars book December 2008
Stellar Structure and Evolution book January 2012
�ber die partiellen Differenzengleichungen der mathematischen Physik journal December 1928
Riemann Solvers and Numerical Methods for Fluid Dynamics book January 2009
A Numerical Scheme for the Compressible Low-Mach Number Regime of Ideal Fluid Dynamics journal January 2017
Approximate Riemann solvers, parameter vectors, and difference schemes journal October 1981
Preconditioned methods for solving the incompressible and low speed compressible equations journal October 1987
Efficient implementation of essentially non-oscillatory shock-capturing schemes journal August 1988
Upwind methods for hyperbolic conservation laws with source terms journal November 1994
Analysis and implementation of TR-BDF2 journal February 1996
On the behaviour of upwind schemes in the low Mach number limit journal January 1999
Well-balanced central finite volume methods for the Ripa system journal November 2015
On the behavior of upwind schemes in the low Mach number limit: II. Godunov type schemes journal May 2004
High order well-balanced finite volume methods for multi-dimensional systems of hyperbolic balance laws journal April 2021
A sequel to AUSM, Part II: AUSM+-up for all speeds journal May 2006
An All-Speed Roe-type scheme and its asymptotic analysis of low Mach number behaviour journal May 2008
A low-Mach number fix for Roe’s approximate Riemann solver journal June 2011
Well-balanced schemes for the Euler equations with gravitation journal February 2014
High-order well-balanced finite volume schemes for the Euler equations with gravitation journal February 2019
Internal Gravity Waves book October 2010
On multigrid solution of the implicit equations of hydrodynamics: Experiments for the compressible Euler equations in general coordinates journal July 2012
New numerical solver for flows at various Mach numbers journal March 2015
A well-balanced finite volume scheme for the Euler equations with gravitation: The exact preservation of hydrostatic equilibrium with arbitrary entropy stratification journal February 2016
Spherical-shell boundaries for two-dimensional compressible convection in a star journal September 2016
Benchmarking the Multidimensional Stellar Implicit Code MUSIC journal March 2017
Testing a one-dimensional prescription of dynamical shear mixing with a two-dimensional hydrodynamic simulation journal July 2017
A well-balanced scheme for the simulation tool-kit A-MaZe: implementation, tests, and first applications to stellar structure journal October 2019
Comparison of 2D and 3D compressible convection in a pre-main sequence star journal June 2020
Fully compressible simulations of waves and core convection in main-sequence stars journal September 2020
Calibrating core overshooting parameters with two-dimensional hydrodynamical simulations journal February 2021
Multidimensional low-Mach number time-implicit hydrodynamic simulations of convective helium shell burning in a massive star journal September 2021
A low-Mach Roe-type solver for the Euler equations allowing for gravity source terms journal January 2017
Riemann Solvers for some Hyperbolic Problems with a Source Term journal January 1999
The Accuracy, Consistency, and Speed of an Electron‐Positron Equation of State Based on Table Interpolation of the Helmholtz Free Energy journal February 2000
Mapping Initial Hydrostatic Models in Godunov Codes journal December 2002
Simulations of Core Convection in Rotating A‐Type Stars: Differential Rotation and Overshooting journal January 2004
Low Mach Number Modeling of Type Ia Supernovae. I. Hydrodynamics journal February 2006
Active Carbon and Oxygen Shell Burning Hydrodynamics journal January 2006
Turbulent Convection in Stellar Interiors. I. Hydrodynamic Simulation journal September 2007
Turbulent Convection in Stellar Interiors. iii. Mean-Field Analysis and Stratification Effects journal April 2013
Internal Gravity Waves in Massive Stars: Angular Momentum Transport journal July 2013
HYDRODYNAMIC SIMULATIONS OF H ENTRAINMENT AT THE TOP OF He-SHELL FLASH CONVECTION journal December 2014
Fish: a Three-Dimensional Parallel Magnetohydrodynamics code for Astrophysical Applications journal August 2011
Well-balanced schemes to capture non-explicit steady states: Ripa model journal January 2016
Idealized hydrodynamic simulations of turbulent oxygen-burning shell convection in 4π geometry journal October 2016
3D hydrodynamic simulations of carbon burning in massive stars journal June 2017
Well-balanced Arbitrary-Lagrangian-Eulerian finite volume schemes on moving nonconforming meshes for the Euler equations of gas dynamics with gravity journal March 2018
3D hydrodynamic simulations of C ingestion into a convective O shell journal October 2019
Dependence of convective boundary mixing on boundary properties and turbulence strength journal February 2019
Logically Rectangular Grids and Finite Volume Methods for PDEs in Circular and Spherical Domains journal January 2008
A Second Order Well-Balanced Finite Volume Scheme for Euler Equations with Gravity journal January 2015
Well-Balanced Unstaggered Central Schemes for the Euler Equations with Gravitation journal January 2016
A Fast and Stable Well-Balanced Scheme with Hydrostatic Reconstruction for Shallow Water Flows journal January 2004
The Evolution of Rotating Stars journal September 2000
Low-Diffusion Flux-Splitting Methods for Flows at All Speeds journal September 1998
An Advanced Leakage Scheme for Neutrino Treatment in Astrophysical Simulations journal April 2016
The last Minutes of Oxygen Shell Burning in a Massive star journal December 2016
A High-performance and Portable All-Mach Regime Flow Solver Code with Well-balanced Gravity. Application to Compressible Convection journal April 2019
Three-dimensional Simulations of Massive Stars. I. Wave Generation and Propagation journal April 2019
An Extension of the Athena++ Framework for Fully Conservative Self-gravitating Hydrodynamics journal February 2021
Capturing Near-Equilibrium Solutions: A Comparison between High-Order Discontinuous Galerkin Methods and Well-Balanced Schemes journal February 2019
Second Order Finite Volume Scheme for Euler Equations with Gravity which is Well-Balanced for General Equations of State and Grid Systems journal February 2019