Narrow Results

This work is devoted to the study of some dynamical features of spherical relativistic locally anisotropic stellar geometry in f(R) gravity. In this paper, a specific configuration of tanh f(R) cosmic model has been taken into account. The mass function through technique introduced by Misner–Sharp has been formulated and with the help of it, various fruitful relations are derived. After orthogonal decomposition of the Riemann tensor, the tanh modified structure scalars are calculated. The role of these tanh modified structure scalars (MSS) has been discussed through shear, expansion as well as Weyl scalar differential equations. The inhomogeneity factor has also been explored for the case of radiating viscous locally anisotropic spherical system and spherical dust cloud with and without constant Ricci scalar corrections.

The aim of this work is to analyze the role of shear evolution equation in the modeling of relativistic spheres in f(R) gravity. We assume that non-static diagonally symmetric geometry is coupled with dissipative anisotropic viscous fluid distributions in the presence of f(R) dark source terms. A specific distribution of f(R) cosmic model has been assumed and the spherical mass function through generic formula introduced by Misner–Sharp has been formulated. Some very important relations regarding Weyl scalar, matter variables and mass functions are being computed. After decomposing orthogonally the Riemann tensor, some scalar variables in the presence of f(R) extra degrees of freedom are calculated. The effects of the three parametric modified structure scalars in the modeling of Weyl, shear, expansion scalar differential equations are investigated. The energy density irregularity factor has been calculated for both anisotropic radiating viscous with varying Ricci scalar and dust cloud with present Ricci scalar corrections.

The aim of this paper is to examine the irregularity factors of a self-gravitating stellar system in the existence of anisotropic fluid. We investigate the dynamics of field equations within $f({𝒢},T)$ background, where ${𝒢}$ is the Gauss–Bonnet invariant and $T$ is the trace of the energy–momentum tensor. Moreover, we have investigated two differential equations using the conservation law and the Weyl tensor. We have determined the irregularity factors of spherical stellar system for some specific conditions of anisotropic and isotropic fluids, dust, radiating and non-radiating systems in $f({𝒢},T)$ gravity. It has been noted that the dissipative matter results in anisotropic stresses and makes the system more complex. The inhomogeneity factor is correlated to one of the scalar functions.

As a follow up to papers dealing firstly with a convective variational formulation in a Milne–Cartan framework for non-dissipative multi-fluid models, and secondly with various ensuing stress energy conservation laws and generalized virial theorems, this work continues a series showing how analytical procedures developed in the context of General Relativity can be usefully adapted for implementation in a purely Newtonian framework where they provide physical insights that are not so easy to obtain by the traditional approach based on a 3+1 space time decomposition. The present paper describes the 4-dimensionally covariant treatment of various dissipative mechanisms, including viscosity in non-superfluid constituents, superfluid vortex drag, ordinary resistivity (mutual friction) between relatively moving non-superfluid constituents, and the transvective dissipation that occurs when matter is transformed from one constituent to another due to chemical disequilibrium such as may be produced by meridional circulation in neutron stars. The corresponding non-dissipative limit cases of vortex pinning, convection and chemical equilibrium are also considered.

This study deals with the spherically symmetric radiating star (with dissipative perfect fluids) with a central vacuum cavity, evolving under the assumption of expansion-free motion. The analytical model of the such dynamics star is discussed in three regimes — diffusion approximation, geodesic motion and self-similarity — and the solutions of dynamical equations are obtained in its complete generality. The structure scalars, which are related to the fundamental properties of fluid distribution, are also discussed which played a very important role in the dynamics of cavity models. It has been shown that energy density is homogeneous but violates the energy condition under quasi-static diffusion approximation.