Damghan University
Astronomical Society of IranIranian Journal of Astronomy and Astrophysics2322-49246120190401Bulk Viscous Bianchi Type VI0 Cosmological Model in the Self-creation Theory of Gravitation and in the General Theory of Relativityعنوان334416010.22128/ijaa.2019.345.1058ENE. A.HegazyMinia university, faculty of Science, Mathematics department, 61519 El Minia, Egypt.0000-0003-3244-4629Journal Article20191101In the second self-creation theory of gravitation and in the general theory of relativity, Bianchi type VI<sub>0</sub> cosmological model in the presence of viscous fluid is studied. An exact solution of the field equations is given by considering the cosmological model yields a constant decelerations parameter q=constant and the coefficients of the metric are taken as A(t)=[c<sub>1</sub>t+c<sub>2</sub>]3L/(q+1)(L+1), B(t)=[c<sub>1</sub>t+c<sub>2</sub>]3/2(q+1)(L+1),C(t)=[c<sub>1</sub> t+ c<sub>2</sub>]3/2(q+1)(L+1),where c<sub>1</sub>,c<sub>2</sub> and L are constants . Effect of the viscosity on the entropy of the universe is given by a composition of the second law of thermodynamics with the the energy momentum tensor T<sub>j</sub><sup>i</sup> with bulk viscous term in a conservative manner. We obtained a formula for calculation the entropy of the universe in term of the viscosity and used it to study and compare the Entropy, Enthalpy, Gibbs energy and Helmholtz energy of the universe in the presence of viscosity term in the self-creation theory of gravitation and in the general theory of relativity. The physical and geometrical properties of the obtained models are discussed.https://ijaa.du.ac.ir/article_160_2327cc011977eef2cc5a380d82267e83.pdf