Publications (9)10.79 Total impact
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Article: The exact solution of the Riemann problem in relativistic MHD with tangential magnetic fields
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ABSTRACT: We have extended the procedure to find the exact solution of the Riemann problem in relativistic hydrodynamics to a particular case of relativistic magnetohydrodynamics in which the magnetic field of the initial states is tangential to the discontinuity and orthogonal to the flow velocity. The wave pattern produced after the break up of the initial discontinuity is analogous to the non--magnetic case and we show that the problem can be understood as a purely relativistic hydrodynamical problem with a modified equation of state. The new degree of freedom introduced by the non-zero component of the magnetic field results in interesting effects consisting in the change of the wave patterns for given initial thermodynamical states, in a similar way to the effects arising from the introduction of tangential velocities. Secondly, when the magnetic field dominates the thermodynamical pressure and energy, the wave speeds approach the speed of light leading to fast shocks and fast and arbitrarily thin rarefaction waves. Our approach is the first non-trivial exact solution of a Riemann problem in relativistic magnetohydrodynamics and it can also be of great interest to test numerical codes against known analytical or exact solutions. Comment: 17 pages, 5 figures, accepted for publication in the Journal of Fluid MechanicsJournal of Fluid Mechanics 12/2005; 544:323-338. · 2.46 Impact Factor -
Article: Assessment of a high-resolution central scheme for the solution of the relativistic hydrodynamics equations
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ABSTRACT: We assess the suitability of a recent high-resolution central scheme developed by Kurganov & Tadmor (2000) for the solution of the relativistic hydrodynamics equations. The novelty of this approach relies on the absence of Riemann solvers in the solution procedure. The computations we present are performed in one and two spatial dimensions in Minkowski spacetime. Standard numerical experiments such as shock tubes and the relativistic flat-faced step test are performed. As an astrophysical application the article includes two-dimensional simulations of the propagation of relativistic jets using both Cartesian and cylindrical coordinates. The simulations reported clearly show the capabilities of the numerical scheme to yield satisfactory results, with an accuracy comparable to that obtained by the so-called high-resolution shock-capturing schemes based upon Riemann solvers (Godunov-type schemes), even well inside the ultrarelativistic regime. Such central scheme can be straightforwardly applied to hyperbolic systems of conservation laws for which the characteristic structure is not explicitly known, or in cases where the exact solution of the Riemann problem is prohibitively expensive to compute numerically. Finally, we present comparisons with results obtained using various Godunov-type schemes as well as with those obtained using other high-resolution central schemes which have recently been reported in the literature. Comment: 14 pages, 12 figures, to appear in A&A07/2004; -
Article: Simulations of Relativistic Jets with GENESIS
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ABSTRACT: The multidimensional relativistic hydrodynamical code GENESIS has been used to obtain first results of {\it 3D} simulations of relativistic jets. We have studied the influence of a slight perturbation of the injection velocity field on the morphodynamics of otherwise axisymmetric relativistic jets.11/1999; -
Article: Relativistic Jets from Collapsars
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ABSTRACT: Using a collapsar progenitor model of MacFadyen & Woosley we have simulated the propagation of an axisymmetric jet through a collapsing rotating massive star with the GENESIS multi-dimensional relativistic hydrodynamic code. The jet forms as a consequence of an assumed (constant or variable) energy deposition in the range $10^{50}$ erg s$^{-1}$ to $10^{51}$ erg s$^{-1}$ within a $30^{\circ}$ cone around the rotation axis. The jet flow is strongly beamed ($\la$ few degrees), spatially inhomogeneous, and time dependent. The jet reaches the surface of the stellar progenitor ($R_{\ast} = 2.98 \times 10^{10} $cm) intact. At breakout the maximum Lorentz factor of the jet flow is 33. After breakout the jet accelerates into the circumstellar medium, whose density is assumed to decrease exponentially and then being constant $\rho_{\rm ext} = 10^{-5}$ gcm$^{-3}$. Outside the star the flow begins to expand also laterally ($v \sim c$), but the beam remains very well collimated. At a distance of $2.54 R_{\ast}$, where the simulation ends, the Lorentz factor has increased to 44. Comment: 7 pages, 4 figures, ApJL accepted11/1999; -
Article: Numerical hydrodynamics in special relativity
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ABSTRACT: This review is concerned with a discussion of numerical methods for the solution of the equations of special relativistic hydrodynamics (SRHD). Particular emphasis is put on a comprehensive review of the application of high-resolution shock-capturing methods in SRHD. Results obtained with different numerical SRHD methods are compared, and two astrophysical applications of SRHD flows are discussed. An evaluation of the various numerical methods is given and future developments are analyzed. Comment: submitted to the electronic journal Living Reviews in Relativity, at http://www.livingreviews.org 72 pages, 14 postscript figures included06/1999; -
Article: A new spherically symmetric general relativistic hydrodynamical code
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ABSTRACT: In this paper we present a full general relativistic one-dimensional hydro-code which incorporates a modern high-resolution shock-capturing algorithm, with an approximate Riemann solver, for the correct modelling of formation and propagation of strong shocks. The efficiency of this code in treating strong shocks is demonstrated by some numerical experiments. The interest of this technique in several astrophysical scenarios is discussed. Comment: 27 pages, 26 figures, accepted ApJ09/1995; -
Article: Stellar hydrodynamics with Glaister's Riemann solver - an approach to the stellar collapse
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ABSTRACT: The Glaister (1988) approximate Riemann solver for solving the Euler gasdynamic equations in one dimension has been implemented in a Lagrangian hydrodynamical code and applied to spherically symmetric stellar collapse. This method is found to allow the efficient treatment of strong shocks generated by stellar collapse. By comparison with Godunov's Riemann solver, Glaister's is 20 percent less time-consuming.Journal of Computational Physics 08/1990; 90:262-266. · 2.31 Impact Factor -
Article: Field theoretical model for nuclear and neutron matter. IV - Radial oscillations of warm cores in neutron stars
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ABSTRACT: The relativistic equations for the radial oscillations of warm cores in neutron stars have been solved and the eigenfrequencies of the fundamental modes have been obtained for a large sample of configurations in relativistic thermal equilibrium. The equation of state used was derived in the frame of a field theoretical model for the analysis of relativistic nuclear and neutron matter at nonzero temperatures. The Lagrangian describing the microdynamics has been introduced by coupling the nucleons to sigma, pi, omega, and rho meson fields in a renormalizable way. Moreover, the results of this paper allow the so-called static stability criterion to be reviewed and a 'central temperature-central density' diagram to be built which displays a well-defined region of stability and admits an evolutive interpretation.The Astrophysical Journal 05/1988; 329:780-789. · 6.02 Impact Factor -
Article: Hydrodynamical Simulations of Relativistic Jets: Morphology, Dynamics and Propagation
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ABSTRACT: Introduction; Hydrodynamical Equations, Numerical Techniques, and Setup; Morphology and Dynamics of Classical Jets; Morphology and Dynamics of Relativistic Jets; Summary and Conclusions100:149.
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Institutions
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1999–2004
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University of Valencia
Valencia, Valencia, Spain
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