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Conservative, specialrelativistic smooth particle hydrodynamics
, 907
"... We derive a new specialrelativistic version of Smooth Particle Hydrodynamics (SPH) from the Lagrangian of an ideal fluid. The new formulation accounts for the terms that stem from nonconstant smoothing lengths, in SPH usually called ”gradh terms”. To handle shocks a refined artificial viscosity s ..."
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We derive a new specialrelativistic version of Smooth Particle Hydrodynamics (SPH) from the Lagrangian of an ideal fluid. The new formulation accounts for the terms that stem from nonconstant smoothing lengths, in SPH usually called ”gradh terms”. To handle shocks a refined artificial viscosity scheme is applied. The performance of this new equation set is explored in a variety of benchmark tests and the results of the new formulation are compared against an earlier specialrelativistic SPH version. The new approach generally yields excellent results. As expected from a Lagrangian method, it performs extremely well in supersonic advection tests, but also for strong relativistic shocks, usually considered a particular challenge for SPH, the method yields convincing results. It is, for example, able to handle Lorentzfactors as large as γ = 50 000 in the socalled wall shock test. Key words: computational fluid dynamics, shocks, special relativity, smooth particle hydrodynamics 1
0SmoothViz: Visualization of Smoothed Particles Hydrodynamics Data
"... Smoothed particle hydrodynamics (SPH) is a completely meshfree method to simulate fluid flow (Gingold & Monaghan, 1977; Lucy, 1977). Rather than representing the physical variables on a fixed grid, the fluid is represented by freely moving interpolation centers (“particles”). Apart from their p ..."
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Smoothed particle hydrodynamics (SPH) is a completely meshfree method to simulate fluid flow (Gingold & Monaghan, 1977; Lucy, 1977). Rather than representing the physical variables on a fixed grid, the fluid is represented by freely moving interpolation centers (“particles”). Apart from their position and velocity these particles carry information about
Compact binary mergers: an astrophysical perspective,” arXiv:1012.0912 [astroph.HE
"... This paper reviews the current understanding of double neutron star and neutron star black hole binaries. It addresses mainly (nuclear) astrophysics aspects of compact binary mergers and thus complements recent reviews that have emphasized the numerical relativity viewpoint. In particular, the pape ..."
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This paper reviews the current understanding of double neutron star and neutron star black hole binaries. It addresses mainly (nuclear) astrophysics aspects of compact binary mergers and thus complements recent reviews that have emphasized the numerical relativity viewpoint. In particular, the paper discusses different channels to release neutronrich matter into the host galaxy, connections between compact binary mergers and short Gammaray bursts and accompanying electromagnetic signals.
One contribution of 15 to a Discussion Meeting Issue ‘New windows on transients across the Universe’.
"... astrophysics, astrochemistry, stars ..."
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Simulation of
"... preplanetesimal collisions with smoothed particle hydrodynamics ..."
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CESSeminar WS 13/14 Smoothed Particle Hydrodynamics
"... 2.1 Interpolation and particle summation...................... 2 ..."
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SPH Entropy Errors and the Pressure Blip
"... The spurious pressure jump at a contact discontinuity, in SPH simulations of the compressible Euler equations is investigated. From the spatiotemporal behaviour of the error, the SPH pressure jump is likened to entropy errors observed for artificial viscosity based finite difference/volume schemes. ..."
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The spurious pressure jump at a contact discontinuity, in SPH simulations of the compressible Euler equations is investigated. From the spatiotemporal behaviour of the error, the SPH pressure jump is likened to entropy errors observed for artificial viscosity based finite difference/volume schemes. The error is observed to be generated at startup and dissipation is the only recourse to mitigate it’s effect. We show that similar errors are generated for the Lagrangian plus remap version of the Piecewise Parabolic Method (PPM) finite volume code (PPMLR). Through a comparison with the direct Eulerian version of the PPM code (PPMDE), we argue that a lack of diffusion across the material wave (contact discontinuity) is responsible for the error in PPMLR. We verify this hypothesis by constructing a more dissipative version of the remap code using a piecewise constant reconstruction. As an application to SPH, we propose a hybrid GSPH scheme that adds the requisite dissipation by utilizing a more dissipative Riemann solver for the energy equation. The proposed modification to the GSPH scheme, and it’s improved treatment of the anomaly is verified for flows with strong shocks in one and two dimensions. The result that dissipation must act across the density and energy equations provides a consistent explanation for many of the hitherto proposed “cures ” or “fixes ” for the problem.