Nonlinear Spinor Fields and its role in Cosmology

Different characteristic of matter influencing the evolution of the Universe has been simulated by means of a nonlinear spinor field. Exploiting the spinor description of perfect fluid and dark energy evolution of the Universe given by an anisotropic Bianchi type-VI, VI$_0$, V, III, I or isotropic Friedmann-Robertson-Walker (FRW) one has been studied. It is shown that due to some restrictions on metric functions, initial anisotropy in the models Bianchi type-VI, VI$_0$, V and III does not die away, while the anisotropic Bianchi type-I models evolves into the isotropic one.Comment: 22 pages, 12 Figure

Nonequilibrium Work distributions for a trapped Brownian particle in a time dependent magnetic field

We study the dynamics of a trapped, charged Brownian particle in presence of a time dependent magnetic field. We calculate work distributions for different time dependent protocols. In our problem thermodynamic work is related to variation of vector potential with time as opposed to the earlier studies where the work is related to time variation of the potentials which depends only on the coordinates of the particle. Using Jarzynski identity and Crook's equality we show that the free energy of the particle is independent of the magnetic field, thus complementing the Bohr-van Leeuwen theorem. We also show that our system exhibits a parametric resonance in certain parameter space.Comment: 4 pages and 5 figure

Natural convection of nanofluids in open rectangular cavity

An investigation of the effect of nano particles on natural convection of water based nanofluids contained in an open rectangular cavity is carried out numerically. The flow pattern and heat transfer characteristics are studied for different values of volume fraction in the range 0 0.2 , Rayleigh number in the range 9 1 Ra 10 and the nano particles with different thermo physical properties. It was found that for low Rayleigh numbers, heat transfer exhibits a decreasing trend for increasing values of volume fraction of oxide nanofluids, whereas for higher values of Rayleigh numbers, an increasing trend of heat transfer was observed due to increase in the volume fraction of nanofluids