A granular instability driven by gravity is studied experimentally and numerically. The instability arises as grains fall in a closed Hele-Shaw cell where a layer of dense granular material is positioned above a layer of air. The initially flat front defined by the grains subsequently develops into a pattern of falling granular fingers separated by rising bubbles of air. A transient coarsening ...

We conduct three-dimensional axisymmetric hydrodynamical numerical simulations of bubble evolution in clusters of galaxies. We inflate bubbles using slow, massive jets with a wide opening angle, and follow their evolution as they rise through the intra-cluster medium (ICM). We find that these jet-inflated bubbles are quite stable, and can reach large distances in the cluster while still maintai...

Existing models invoking AGN activty to resolve the cooling flow conundrum in galaxy clusters focus exclusively on the role of the central galaxy. Such models require finetuning of highly uncertain microscopic transport properties to distribute the thermal thermal over the entire cluster cooling core. We propose that the ICM is instead heated by multiple, spatially distributed AGNs. The central...

This communication describes the results of bubble rise simulations using a lattice Boltzmann method and a front-tracking finite-difference method. The simulations, performed in a 2-D periodic box, consider two specific examples: a steadily rising bubble and a bubble rising in an oscillatory manner with accompanying shape change. We compare the shapes and rise velocities of the steadily rising ...

In the movement process of continuous bubbles, different liquid-flow state and initial temperature bubbles have important influence on bubble heat transfer. this study, flow transfer characteristics high in normal liquid are investigated. The rising studied by numerical simulation compared with experimental results for verification. show that shape, velocity affected position bubble. Because cl...

The numerical investigation of large bubbles rising under an inclined plane is presented. A numerical method for the simulation of fluid flows with complex free surfaces is presented, in which the liquid is assumed to be Newtonian, while gas bubbles are assumed to be compressible. A volume-of-fluid method is used to track the liquid domain. A time splitting algorithm allows to decouple the adve...