  In this paper, we study anisotropic Bianchi-V universe with magnetic field
and bulk viscous fluid in string cosmology. Exact solutions of the field
equations are obtained by using the equation of state for a cloud of strings,
and a relationship between bulk viscous coefficient and scalar expansion. The
bulk viscous coefficient is assumed to be inversely proportional to the
expansion scalar. It is interesting to examine the effects of magnetized bulk
viscous string model in early and late stages of the evolution of the universe.
This paper presents the different string models like geometrical (Nambu
string), Takabayashi (p-string) and Reddy string models by taking certain
physical conditions. We discuss the nature of the classical potential for
viscous fluid with and without magnetic field. We find that the introduction of
bulk viscosity with and without magnetic field results in rapid change in
density parameters and in the classical potential. The presence of bulk
viscosity prevents the universe to be empty in its future evolution. The other
physical and geometrical aspects of each string model are discussed in detail.
