Browsing by Author "Rajani, K.V."

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    Comparative Study of Bulk and Surface Pressure of Charged AdS Black Hole
    (Springer Science and Business Media Deutschland GmbH, 2021) Rajani, K.V.; Vaid, D.
    One of the most interesting areas of research is the study of thermodynamic properties of black holes. In the extended phase, cosmological constant has been identified with the thermodynamic pressure of the black hole and phase transitions similar to Van der waals fluid is observed. On other side, fluid gravity correspondence which gives the connection between fluid on a d dimensional boundary and gravity theory in d + 1-dimensional bulk relates Einstein’s equations in the bulk with Navier-Stokes equations on the boundary. Projecting Einsteins equation onto a black hole horizon gives Damours Navier-Stokes equation and fluid pressure is found to be κ8π. In our present work, we are comparing the thermodynamic quantities in the bulk and boundary of charged AdS black holes. © 2021, Springer Nature Singapore Pte Ltd.
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    Effect of dark energy in geometrothermodynamics and phase transitions of regular Bardeen AdS black hole
    (2019) Ahmed, Rizwan, C.L.; Naveena, Kumara, A.; Rajani, K.V.; Vaid, D.; Ajith, K.M.
    We study the thermodynamics and geometrothermodynamics of regular Bardeen-AdS black hole with quintessence. The thermodynamics of the black hole is scrutinised using Temperature Entropy (T S), Pressure Volume (P v) and Gibbs energy plots, which indicates a critical behaviour. The behaviour is also confirmed from the divergence of specific heat against entropy, which shows a second-order phase transition. Furthermore, we observe that the quintessence state parameter ? shifts the transition point to lower entropy values. Using the concept of thermodynamic Ruppeiner and Weinhold geometry, we calculated the thermodynamic curvature scalar RR and RW in the quintessence dark energy regime (?= - 2 / 3 ). While these curvature scalars enable us to identify the critical behaviour, they do not show divergence at the phase transition points observed in specific heat study. To resolve this puzzle, we have adopted the method of geometrothermodynamics proposed by Hernando Quevedo. Choosing a Legendre invariant Quevedo metric, the curvature scalar RQ shows singularity at the same point as seen in the specific heat divergence. 2019, Springer Science+Business Media, LLC, part of Springer Nature.
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    Effect of dark energy in geometrothermodynamics and phase transitions of regular Bardeen AdS black hole
    (Springer, 2019) Ahmed Rizwan, C.L.; Naveena Kumara, A.; Rajani, K.V.; Vaid, D.; Ajith, K.M.
    We study the thermodynamics and geometrothermodynamics of regular Bardeen-AdS black hole with quintessence. The thermodynamics of the black hole is scrutinised using Temperature–Entropy (T–S), Pressure–Volume (P–v) and Gibbs energy plots, which indicates a critical behaviour. The behaviour is also confirmed from the divergence of specific heat against entropy, which shows a second-order phase transition. Furthermore, we observe that the quintessence state parameter ? shifts the transition point to lower entropy values. Using the concept of thermodynamic Ruppeiner and Weinhold geometry, we calculated the thermodynamic curvature scalar RR and RW in the quintessence dark energy regime (?= - 2 / 3 ). While these curvature scalars enable us to identify the critical behaviour, they do not show divergence at the phase transition points observed in specific heat study. To resolve this puzzle, we have adopted the method of geometrothermodynamics proposed by Hernando Quevedo. Choosing a Legendre invariant ‘Quevedo’ metric, the curvature scalar RQ shows singularity at the same point as seen in the specific heat divergence. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
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    Phase transition and thermodynamic geometry of regular Bardeen black hole in higher dimensions
    (American Institute of Physics Inc., 2020) Rajani, K.V.; Ahmed Rizwan, C.L.A.; Naveena Kumara, A.N.
    In this work we study the thermodynamic properties and phase transition of higher dimensional regular Bardeen black hole in AdS spacetime. The black hole thermodynamics is studied using Hawking temperature vs Bekenstein entropy (T - S) plot, which shows a critical behaviour. This is followed by the investigation of the phase transition by observing the divergence of specific heat. The critical behaviour of the blackhole is further analysed in detail via Ruppeiner geometry. The divergence behaviour similar to specific heat is found in Ruppeiner curvature scalar confirms a second order phase transition. © 2020 Author(s).
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    Regular Bardeen AdS black hole as a heat engine
    (Elsevier B.V., 2020) Rajani, K.V.; Ahmed Rizwan, C.L.A.; Naveena Kumara, A.N.; Vaid, D.; Ajith, K.M.
    We investigate the thermodynamic phase transition and heat engine efficiency in regular Bardeen AdS black hole. The thermodynamics of the black hole is analyzed in extended phase space. A first order phase transition analogous to van der Waal system is evident from this study, which is affirmed by the specific heat divergence at the critical points. A conventional heat engine is constructed by considering the black hole as working substance. The efficiency is obtained via a thermodynamic cycle in the P?V plane, which receives and ejects heat. The heat engine efficiency is improved by adding a quintessence field. The analytical expression for heat engine efficiency is derived in terms of quintessence dark energy parameter. © 2020 The Author(s)