相关论文: Bubbles as tracers of heat input to cooling flows
Using idealized 1-D Eulerian hydrodynamic simulations, we contrast the behavior of isolated supernovae with the superbubbles driven by multiple, collocated supernovae. Continuous energy injection via successive supernovae going off within…
Conduction may play an important role in reducing cooling flows in galaxy clusters. We analyse a sample of sixteen objects using Chandra data and find that a balance between conduction and cooling can exist in the hotter clusters (T > 5…
We investigate the effect of mass-loading from embedded clouds on the evolution of wind-blown bubbles. We use 1D hydrodynamical calculations and assume that the clouds are numerous enough that they can be treated in the continuous limit,…
Cold atomic gases offer the prospect of simulating the physics of the very early universe in the laboratory. In the condensate phase, the gas is described by a field theory with key features of high energy particle theory. This paper…
Our interest goes to the power injected in a heated granular gas and to the possibility to interpret it in terms of entropy flow. We numerically determine the distribution of the injected power by means of Monte-Carlo simulations. Then, we…
It is now widely accepted that heating processes play a fundamental role in galaxy clusters, struggling in an intricate but fascinating `dance' with its antagonist, radiative cooling. Last generation observations, especially X-ray, are…
We review the general properties of the intracluster medium (ICM) in clusters that host a cooling flow, and in particular the effects on the ICM of the injection of hot plasma by a powerful active galactic nucleus (AGN). It is observed…
3D-Particle Tracking (3D-PTV) and Phase Sensitive Constant Temperature Anemometry in pseudo-turbulence--i.e., flow solely driven by rising bubbles-- were performed to investigate bubble clustering and to obtain the mean bubble rise…
We examine the energy distribution in a three-dimensional model granular system contained in an open cylinder under the influence of gravity. Energy is supplied to the system by a vibrating base. We introduce spatially resolved, partial…
Buoyant bubbles of relativistic plasma in cluster cores plausibly play a key role in conveying the energy from a supermassive black hole to the intracluster medium (ICM) - the process known as radio-mode AGN feedback. Energy conservation…
The discrepancy between expected and observed cooling rates of X-ray emitting gas has led to the {\it cooling flow problem} at the cores of clusters of galaxies. A variety of models have been proposed to model the observed X-ray spectra and…
Active galactic nuclei are clearly heating gas in `cooling flows'. The effectiveness and spatial distribution of the heating are controversial. We use three-dimensional simulations on adaptive grids to study the impact on a cooling flow of…
The bubbles involved in sonochemistry and other applications of cavitation oscillate inertially. A correct estimation of the wave attenuation in such bubbly media requires a realistic estimation of the power dissipated by the oscillation of…
Bubbles driven by energy and mass injection from small scales are ubiquitous in astrophysical fluid systems and essential to feedback across multiple scales. In particular, O stars in young clusters produce high velocity winds that create…
Over the past several years, numerous examples of X-ray cavities coincident with radio sources have been observed in so-called "cool core" clusters of galaxies. Motivated by these observations, we explore the evolution and the effect of…
Heat transfer to a granular flow is comprised of two resistances in series: near the wall and within the bulk particle bed, neither of which is well understood due to the lack of experimental probes to separate their respective…
Preferential concentration of inertial particles by turbulence is a well recognized phenomenon. This study investigates how this phenomenon impacts the mean heat transfer between the fluid phase and the particle phase. Using direct…
Results of direct numerical simulations and laboratory experiments have been used in order to show that the buoyancy driven bubbly flows at high gas volume fraction are mixed by deterministic chaos with typical exponential spectrum of the…
Many recent works on the observed galaxy clusters in the X-rays highlight broadly two classes of exclusive energy carriers - sound waves and turbulence. In order to understand this dichotomy, we design an idealized three-dimensional…
We investigate by direct numerical simulations the flow that rising bubbles cause in an originally quiescent fluid. We employ the Eulerian-Lagrangian method with two-way coupling and periodic boundary conditions. In order to be able to…