Related papers: An analytic relation for the thickness of accretio…
The influence of viscosity on the flow behaviour in spherically symmetric accretion, has been studied here. The governing equation chosen has been the Navier-Stokes equation. It has been found that at least for the transonic solution,…
We present a new semi-analytic formalism for modeling metal absorption lines that emerge from a clumpy galactic environment, ALPACA. We predict the ''down-the-barrel'' (DTB) metal absorption line profiles and the EW of absorption at…
We present the two-dimensional inflow-outflow solutions of radiation hydrodynamic (RHD) equations of supercritical accretion flows. Compared with prior studies, we include all components of the viscous stress tensor. We assume steady state…
We present results of a semi-analytic model (SAM) that includes cold accretion and a porosity-based prescription for star formation. We can recover the puzzling observational results of low $V/\sigma$ seen in various massive disk or…
We obtain an extension of Bjorken's 1+1 dimensional scaling relativistic flow solution to relativistic transverse velocities with cylindrical symmetry in 1+3 dimensions at constant, homogeneous pressure (vanishing sound velocity). This can…
The global structure of optically thin advection dominated accretion flows which are composed of two-temperature plasma around black holes is calculated. We adopt the full set of basic equations including the advective energy transport in…
A new numerical algorithm for calculating isothermal wind accretion flows has been developed and is applied here to the analysis of the hydrodynamics of two-dimensional plane symmetric accretion flows in wind-fed sources. Polar coordinates…
Recent numerical simulations of radiatively inefficient accretion flows onto compact objects have shown that convection is a general feature in such flows. Dissipation of rotational and gravitational energies in the accretion flows results…
Radiative transfer equation in an accretion disk wind is examined analytically and numerically under the plane-parallel approximation in the subrelativistic regime of $(v/c)^1$, where $v$ is the wind vertical velocity. Emergent intensity is…
A simple analytical solution for turbulent plane Couette flow is obtained from a subset of the Navier-Stokes equations. This approach analyses the effect of the unsteady state Lagrangian diffusion of viscous momentum on the smoothed phase…
We consider advection of a passive scalar theta(t,r) by an incompressible large-scale turbulent flow. In the framework of the Kraichnan model the whole PDF's (probability distribution functions) for the single-point statistics of theta and…
Acoustic perturbations in a parallel relativistic flow of an inviscid fluid are considered. The general expression for the frequency of the sound waves in a uniformly (with zero shear) moving medium is derived. It is shown that relativity…
Hydrodynamics predicts long-lived sound and shear waves. Thermal fluctuations in these waves can lead to the diffusion of momentum density, contributing to the shear viscosity and other transport coefficients. Within viscous hydrodynamics…
We consider axisymmetric viscous accretion flows where a fraction f of the viscously dissipated energy is advected with the accreting gas as stored entropy and a fraction 1-f is radiated. When f is small (i.e. very little advection), our…
Accretion flows onto underluminous black holes, such as Sagittarius A* at the center of our galaxy, are dilute (mildly collisional to highly collisionless), optically thin, and radiatively inefficient. Therefore, the accretion properties of…
We revisit the vertical structure of black hole accretion disks in spherical coordinates. By comparing the advective cooling with the viscous heating, we show that advection-dominated disks are geometrically thick, i.e., with the…
The optical conductivity along and perpendicular to the planes is calculated assuming strong k-dependence of the scattering rate and the c-axis hopping parameter. Closed analytical expressions for the optical conductivy along these…
The elliptic flow $v_2$ and the ratio of the shear viscosity over the entropy density, $\eta/s$, of gluon matter are calculated from the perturbative QCD (pQCD) based parton cascade Boltzmann approach of multiparton scatterings. For Au+Au…
The transport coefficients of strongly interacting matter are currently subject of intense theoretical and phenomenological studies due to their relevance for the characterization of the quark-gluon plasma produced in ultra relativistic…
An accretion flow around a black hole has a saddle type sonic point just outside the event horizon to guarantee that the flow enters the black hole supersonically. This feature exclusively present in strong gravity limit makes its marks in…