DSpace Repository :: Browsing Master's theses by Author "Berdibek, Shapagat"

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Interaction of Turbulence with Shock Waves in the Context of Core-Collapse Supernovae
(Nazarbayev University School of Science and Technology, 2017-04) Berdibek, Shapagat
The supernova explosion of massive stars is a complex physical event. Nuclear shell burning in the nal stages of the lives of massive stars is accompanied by strong turbulent convection. The resulting uctuations aid supernova explosion by amplifying the non-radial ow in the post-shock region. We investigate the physical mechanism behind this ampli cation using a linear perturbation theory. We model the shock wave as a one-dimensional planar discontinuity and consider its interaction with vorticity and entropy perturbations in the upstream ow. We nd that, as the perturbations cross the shock, their total turbulent kinetic energy is ampli ed by a factor of 2, while the average linear size of turbulent eddies decreases by about the same factor. We also study the e ects of the interaction of acoustic perturbations with the shock wave. We determine that the post-shock turbulent kinetic energy is dominated by vorticity waves. In addition, we nd that the kinetic energy ampli cation of perturbations increases as / M21 . Finally, we discuss the implication of our results for the supernova explosion mechanism. We show that the upstream perturbations can decrease the critical neutrino luminosity for producing explosion by several percent.