A generalized class one static solution.

In literature, there are three simplest methods of solving Einstein's field equations, namely, (a) assuming conformally flat spacetime, (b) using conformal killing vector and (c) using Karmarkar conditions. In all these approaches the two metric functions g t t and g r r are link via a bridge. However, the first two approaches are facing a critical failure while determining central red-shift while the last method always yields well-behaved solution. Therefore, we are adopting the last method and discover a generalized class one solution. It is found that the maximum mass and radius of the compact star describe by the solution strongly depends on the parameter n. As n increases the maximum mass and radius also increases. For n = 3.3 , M m a x = 1.459 M ⊙ and R m a x = 9.52  km , and for n = 4.8 have M m a x = 1.766 M ⊙ with R m a x = 10.31  km . For n = 4.8 the equation of state is behaving linearly as the speed of sound is almost constant at 0.333. In overall the presented solution is well-behaved in all respects.

Nonlinear effects in the bounded dust-vortex flow in plasma.

The vortex structures in a cloud of electrically suspended dust in a streaming plasma constitutes a driven system with a rich nonlinear flow regime. Experimentally recovered toroidal formations of this system have motivated study of its volumetrically driven-dissipative vortex flow dynamics using two-dimensional hydrodynamics in the incompressible Navier-Stokes regime. Nonlinear equilibrium solutions are obtained for this system where a nonuniformly driven two-dimensional dust flow exhibits distinct regions of localized accelerations and strong friction caused by stationary fluids at the confining boundaries resisting the dust flow. In agreement with observations in experiments, it is demonstrated that the nonlinear effects appear in the limit of small viscosity, where the primary vortices form scaling with the most dominant spatial scales of the domain topology and develop separated virtual boundaries along their periphery. This separation is triggered beyond a critical dust viscosity that signifies a structural bifurcation. Emergence of uniform vorticity core and secondary vortices with a newer level of identical dynamics highlights the applicability of the studied dynamics to gigantic vortex flows, such as the Jovian great red spot, to microscopic biophysical intracellular activity.

Analytic structure of a drag-driven confined dust vortex flow in plasma.

Flow structure of a dust medium electrostatically suspended and confined in a plasma presents a unique setup where the spatial scale of a volumetric drive by the plasma flow might exceed that of the boundaries confining the dust. By means of a formal implementation of a two-dimensional hydrodynamic model to a confined dust flow and its analytic curvilinear solutions, it is shown that the eigenmode spectrum of the dust vortex flow can lose correlations with the driving field even at the low dust Reynolds numbers as a result of strong shear and finer scales introduced in the equilibrium dust vorticity spectrum by the boundaries. While the boundary effects can replace the desired turbulent processes unavailable in this regime, the shear observable in most of the dust vortex flows is identified to have a definite exponent of dependence on the dust viscosity over a substantially large range of the latter. These results and scalings allow quantification of the notion of dusty plasma medium as a paradigm for a wide range of natural flow processes having scales inaccessible to ordinary laboratory experiments.