Relativistic Smoothed Particle Hydrodynamics C. E. Aguiar, T. Kodama U. F. Rio de Janeiro T. Osada, Y. Hama U. São Paulo Outline • Relativistic hydrodynamics • Relativistic SPH • Entropy-based SPH • Shocks and artificial viscosity
Energy-momentum conservation: enthalpy per baryon:
Momentum equation: Energy equation:
Entropy conservation: s = entropy density (rest frame)
Lagrangian Equations
SPH • Developed to study gas dynamics in • • astrophysical systems. Lagrangian method. No grids. Arbitrary geometries. Equally applicable in 1, 2 and 3 space dimensions. - L. Lucy, Astron. J. 82, 1013 (1977) - R. Gingold, J. Monaghan, MNRAS 181, 378 (1977) Reviews: - J. Monaghan, Annu. Rev. Astron. Astrophys. 30, 543 (1992) - L. Hernquist, N. Katz, Ap. J. Suppl. 70, 419 (1989)
Smoothing h 0 Error: x
Particles "Monte-Carlo" sampling nb = baryon number of ''particle'' b
Different ways of writing SP estimates (we omit the SP subscript from now on):
Derivatives No need for finite differences and grids: i-1 D i+1
More than one way of calculating derivatives:
Moving the Particles
Momentum equation Energy equation
Energy and Momentum
Entropy equation
Particle Velocity ? equation for g:
RSPH Equations
Baryon-Free Matter
Lagrangian equations:
Entropy-based RSPH
Ultrarelativistic Pion Gas
Pion Gas Rarefaction Wave
Pion Gas Landau Solution
Shock Waves numerical calculation shock wave x
Pion Gas Shock Wave
Artificial Viscosity
Second Law of Thermodynamics: Thermodynamically normal matter: Thermodynamically anomalous matter: