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Description
The Anderson-Witting relaxation-time approximation (RTA), providing a simple approximation of the Boltzmann collision integral, suffers from the drawback that the single relaxation time $\tau_R$ controls all transport coeffcients (shear and bulk viscosities, diffusivity, higher-order coefficients) [1]. Our Shakhov-like extension systematically introduces extra parameters allowing the individual control of bulk, shear and diffusion phenomena [2], as well as shear-diffusion or bulk-shear cross-couplings [3]. The success of the scheme is demonstrated via numerical simulations in the context of non-conformal Bjorken flow [2,3], sound waves [2,3] and the shock tube (Riemann) problem [3], where our results are validated against BAMPS results for ultrarelativistic hard spheres [4].
[1] Victor E. Ambruș, E. Molnár, D. H. Rischke, Transport coefficients of second-order relativistic fluid dynamics in the relaxation-time approximation, Phys. Rev. D 106 (2022) 076005.
[2] Victor E. Ambruș, E. Molnár, Shakhov-type extension of the relaxation time approximation in relativistic kinetic theory and second-order fluid dynamics, Phys. Lett. B 855 (2024) 138795.
[3] Victor E. Ambruș, D. Wagner, High-order Shakhov-like extension of the relaxation time approximation in relativistic kinetic theory, Phys. Rev. D 110 (2024) 056002.
[4] G. S. Denicol et al (DNBMXRG), Solving the heat-flow problem with transient relativistic fluid dynamics, Phys. Rev. D 89 (2014) 074005.
| Category | Theory |
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