Relativistic Hydrodynamics and Symmetry: Theory, Methods and Applications

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Physics".

Deadline for manuscript submissions: 30 April 2024 | Viewed by 19721

Special Issue Editor


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Guest Editor
1. Institute for Theoretical Physics, University of Wroclaw, pl. M. Borna 9, 50-204 Wroclaw, Poland
2. Frankfurt Institute for Advanced Studies, Ruth-Moufang str. 1, 60438 Frankfurt am Main, Germany
Interests: compact stars; nuclear matter; quark gluon plasma; quantum fields; statistical physics
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Special Issue Information

Dear Colleagues,

The open access journal Symmetry has launched a new Special Issue entitled "Relativistic Hydrodynamics and Symmetry: Theory, Methods and Applications". It will cover all aspects of the physics of relativistic hydrodynamics and serve as a useful reference for researchers and students on the current problems in this area of research.

Relativistic hydrodynamics is an effective framework for the long-wavelength and low-frequency description of matter under a wide variety of conditions, ranging from nuclear collisions in heavy-ion experiments to the large-scale structure of galaxies. It has been successfully applied in recent years to describe the elementary matter in heavy-ion experiments, including the formation of quark–gluon plasma at the RHIC and LHC. Another important area of research where tremendous progress has been achieved is the physics of compact stars, with the magneto-hydrodynamics description of the binary neutron star mergers being one such example.

We cordially invite you, as an expert in this field, to contribute an original article or balanced review to this Special Issue.

The papers will be peer-reviewed and will be published online as soon as they are accepted. We are looking forward to hearing about your contributions to this issue and the potential future collaboration in producing a comprehensive issue.

Prof. Dr. Armen Sedrakian
Guest Editor

Manuscript Submission Information

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Keywords

  • Symmetry
  • Heavy Ion Collisions
  • Neutron Stars
  • Hydrodynamics
  • General Relativity
  • Gravitational waves

Published Papers (7 papers)

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Research

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13 pages, 27070 KiB  
Article
General Relativistic Stability and Gravitational Wave Content of Rotating Triaxial Neutron Stars
by Yufeng Luo, Antonios Tsokaros, Roland Haas and Kōji Uryū
Symmetry 2024, 16(3), 343; https://doi.org/10.3390/sym16030343 - 13 Mar 2024
Viewed by 530
Abstract
Triaxial neutron stars can be sources of continuous gravitational radiation detectable by ground-based interferometers. The amplitude of the emitted gravitational wave can be greatly affected by the state of the hydrodynamical fluid flow inside the neutron star. In this work, we examine the [...] Read more.
Triaxial neutron stars can be sources of continuous gravitational radiation detectable by ground-based interferometers. The amplitude of the emitted gravitational wave can be greatly affected by the state of the hydrodynamical fluid flow inside the neutron star. In this work, we examine the most triaxial models along two sequences of constant rest mass, confirming their dynamical stability. We also study the response of a triaxial figure of quasiequilibrium under a variety of perturbations that lead to different fluid flows. Starting from the general relativistic compressible analog of the Newtonian Jacobi ellipsoid, we perform simulations of Dedekind-type flows. We find that in some cases the triaxial neutron star resembles a Riemann-S-type ellipsoid with minor rotation and gravitational wave emission as it evolves towards axisymmetry. The present results highlight the importance of understanding the fluid flow in the interior of a neutron star in terms of its gravitational wave content. Full article
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13 pages, 336 KiB  
Article
Mapping GENERIC Hydrodynamics into Carter’s Multifluid Theory
by Lorenzo Gavassino
Symmetry 2024, 16(1), 78; https://doi.org/10.3390/sym16010078 - 06 Jan 2024
Cited by 1 | Viewed by 878
Abstract
We show that the GENERIC model for relativistic heat conduction is a multifluid of Carter; this allows one to compute the multifluid constitutive relations directly from the GENERIC formalism. As a quick application, we prove that in the limit of infinite heat conductivity, [...] Read more.
We show that the GENERIC model for relativistic heat conduction is a multifluid of Carter; this allows one to compute the multifluid constitutive relations directly from the GENERIC formalism. As a quick application, we prove that in the limit of infinite heat conductivity, GENERIC heat conduction reduces to the relativistic two-fluid model for superfluidity. This surprising “crossover” is a consequence of relativistic causality: if diffusion happens too fast, all the diffusing charge cumulates on the surface of the light cone, and it eventually travels at the speed of light like a wave. Our analysis is non-perturbative and carried out in a fully non-linear regime. Full article
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34 pages, 3749 KiB  
Article
Thinking Outside the Box: Numerical Relativity with Particles
by Stephan Rosswog, Peter Diener and Francesco Torsello
Symmetry 2022, 14(6), 1280; https://doi.org/10.3390/sym14061280 - 20 Jun 2022
Cited by 9 | Viewed by 5557
Abstract
The observation of gravitational waves from compact objects has now become an active part of observational astronomy. For a sound interpretation, one needs to compare such observations against detailed Numerical Relativity simulations, which are essential tools to explore the dynamics and physics of [...] Read more.
The observation of gravitational waves from compact objects has now become an active part of observational astronomy. For a sound interpretation, one needs to compare such observations against detailed Numerical Relativity simulations, which are essential tools to explore the dynamics and physics of compact binary mergers. To date, essentially all simulation codes that solve the full set of Einstein’s equations are performed in the framework of Eulerian hydrodynamics. The exception is our recently developed Numerical Relativity code SPHINCS_BSSN which solves the commonly used BSSN formulation of the Einstein equations on a structured mesh and the matter equations via Lagrangian particles. We show here, for the first time, SPHINCS_BSSN neutron star merger simulations with piecewise polytropic approximations to four nuclear matter equations of state. In this set of neutron star merger simulations, we focus on perfectly symmetric binary systems that are irrotational and have 1.3 M masses. We introduce some further methodological refinements (a new way of steering dissipation, an improved particle–mesh mapping), and we explore the impact of the exponent that enters in the calculation of the thermal pressure contribution. We find that it leaves a noticeable imprint on the gravitational wave amplitude (calculated via both quadrupole approximation and the Ψ4 formalism) and has a noticeable impact on the amount of dynamic ejecta. Consistent with earlier findings, we only find a few times 103M as dynamic ejecta in the studied equal mass binary systems, with softer equations of state (which are more prone to shock formation) ejecting larger amounts of matter. In all of the cases, we see a credible high-velocity (∼0.50.7c) ejecta component of ∼104M that is launched at contact from the interface between the two neutron stars. Such a high-velocity component has been suggested to produce an early, blue precursor to the main kilonova emission, and it could also potentially cause a kilonova afterglow. Full article
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14 pages, 1749 KiB  
Article
Total and Partial Shear Viscosity in Heavy-Ion Collisions at Energies of BES, FAIR and NICA
by Maksym Teslyk, Larisa Bravina and Evgeny Zabrodin
Symmetry 2022, 14(4), 634; https://doi.org/10.3390/sym14040634 - 22 Mar 2022
Viewed by 1352
Abstract
We calculated the shear viscosity of hot and dense nuclear matter produced in a symmetric system of central gold–gold collisions at energies of BES RHIC, FAIR and NICA. For calculations of the collisions, the transport model UrQMD was employed. The shear viscosity was [...] Read more.
We calculated the shear viscosity of hot and dense nuclear matter produced in a symmetric system of central gold–gold collisions at energies of BES RHIC, FAIR and NICA. For calculations of the collisions, the transport model UrQMD was employed. The shear viscosity was obtained within the Green–Kubo formalism. The hadron resonance gas model was used to determine temperature and chemical potentials of baryon charge and strangeness out of microscopic model calculations. In contrast to our previous works, we determined the partial viscosity of the main hadron species, such as nucleons, pions, kaons and Lambdas, via the nucleon–nucleon, pion–pion and so forth, correlators. A decrease in the beam energy from Elab=40 to 10 AGeV leads a to rise in baryon shear viscosity accompanied by a drop in the shear viscosity of mesons. The ratio of total shear viscosity to entropy density also decreases. Full article
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15 pages, 5656 KiB  
Article
Resummed Relativistic Dissipative Hydrodynamics
by Huda Alalawi, Mubarak Alqahtani and Michael Strickland
Symmetry 2022, 14(2), 329; https://doi.org/10.3390/sym14020329 - 05 Feb 2022
Cited by 11 | Viewed by 1118
Abstract
In this review, we present the motivation for using relativistic anisotropic hydrodynamics to study the physics of ultrarelativistic heavy-ion collisions. We then highlight the main ingredients of the 3+1D quasiparticle anisotropic hydrodynamics model including the underlying symmetry assumptions and present phenomenological comparisons with [...] Read more.
In this review, we present the motivation for using relativistic anisotropic hydrodynamics to study the physics of ultrarelativistic heavy-ion collisions. We then highlight the main ingredients of the 3+1D quasiparticle anisotropic hydrodynamics model including the underlying symmetry assumptions and present phenomenological comparisons with experimental data at different collision energies. These comparisons show that anisotropic hydrodynamics can describe many bulk observables of the quark-gluon plasma. Full article
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Review

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20 pages, 392 KiB  
Review
Phenomenological Relativistic Second-Order Hydrodynamics for Multiflavor Fluids
by Arus Harutyunyan and Armen Sedrakian
Symmetry 2023, 15(2), 494; https://doi.org/10.3390/sym15020494 - 13 Feb 2023
Cited by 2 | Viewed by 1099
Abstract
In this work, we perform a phenomenological derivation of the first- and second-order relativistic hydrodynamics of dissipative fluids. To set the stage, we start with a review of the ideal relativistic hydrodynamics from energy–momentum and particle number conservation equations. We then go on [...] Read more.
In this work, we perform a phenomenological derivation of the first- and second-order relativistic hydrodynamics of dissipative fluids. To set the stage, we start with a review of the ideal relativistic hydrodynamics from energy–momentum and particle number conservation equations. We then go on to discuss the matching conditions to local thermodynamical equilibrium, symmetries of the energy–momentum tensor, decomposition of dissipative processes according to their Lorentz structure, and, finally, the definition of the fluid velocity in the Landau and Eckart frames. With this preparatory work, we first formulate the first-order (Navier–Stokes) relativistic hydrodynamics from the entropy flow equation, keeping only the first-order gradients of thermodynamical forces. A generalized form of diffusion terms is found with a matrix of diffusion coefficients describing the relative diffusion between various flavors. The procedure of finding the dissipative terms is then extended to the second order to obtain the most general form of dissipative function for multiflavor systems up to the second order in dissipative fluxes. The dissipative function now includes in addition to the usual second-order transport coefficients of Israel–Stewart theory also second-order diffusion between different flavors. The relaxation-type equations of second-order hydrodynamics are found from the requirement of positivity of the dissipation function, which features the finite relaxation times of various dissipative processes that guarantee the causality and stability of the fluid dynamics. These equations contain a complete set of nonlinear terms in the thermodynamic gradients and dissipative fluxes arising from the entropy current, which are not present in the conventional Israel–Stewart theory. Full article
63 pages, 1303 KiB  
Review
New Developments in Relativistic Magnetohydrodynamics
by Koichi Hattori, Masaru Hongo and Xu-Guang Huang
Symmetry 2022, 14(9), 1851; https://doi.org/10.3390/sym14091851 - 05 Sep 2022
Cited by 21 | Viewed by 7879
Abstract
Relativistic magnetohydrodynamics (RMHD) provides an extremely useful description of the low-energy long-wavelength phenomena in a variety of physical systems from quark–gluon plasma in heavy-ion collisions to matters in supernova, compact stars, and early universe. We review the recent theoretical progresses of RMHD, such [...] Read more.
Relativistic magnetohydrodynamics (RMHD) provides an extremely useful description of the low-energy long-wavelength phenomena in a variety of physical systems from quark–gluon plasma in heavy-ion collisions to matters in supernova, compact stars, and early universe. We review the recent theoretical progresses of RMHD, such as a formulation of RMHD from the perspective of magnetic flux conservation using the entropy–current analysis, the nonequilibrium statistical operator approach applied to quantum electrodynamics, and the relativistic kinetic theory. We discuss how the transport coefficients in RMHD are computed in kinetic theory and perturbative quantum field theories. We also explore the collective modes and instabilities in RMHD with a special emphasis on the role of chirality in a parity-odd plasma. We also give some future prospects of RMHD, including the interaction with spin hydrodynamics and the new kinetic framework with magnetic flux conservation. Full article
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