We study the spherical collapse of non-top-hat matter fluctuations in presence dark energy with arbitrary sound speed. The model is described by a system partial differential equations solved using pseudo-spectral method collocation points. This can reproduce known analytical solutions linear regime an accuracy better than $10^{-6}\%$ and $10^{-2}\%$ for virialization threshold given usual mode...

Material deformation and pitting from cavitation bubble collapse is investigated using fluid and material dynamics and their interaction. In the fluid, a novel hybrid approach, which links a boundary element method and a compressible finite difference method, is used to capture non-spherical bubble dynamics and resulting liquid pressures efficiently and accurately. The bubble dynamics is intima...

In this paper we present a mathematical model for estimate the collapse time of a gas bubble in a vane of a oil gerotor pump. This amount of time cannot be greater of the total time spent by the pump for filling and then emptying out a vane in a single revolution, otherwise there is a loss of lubrication between internal and external gears. We assume that oil is incompressible and viscous, the ...

The collapse and fragmentation of initially filamentary, magnetic molecular clouds is calculated in three dimensions with a gravitational, radiative hydrodynamics code. The code includes magnetic field effects in an approximate manner: magnetic pressure, tension, braking, and ambipolar diffusion are all modelled. The parameters varied are the ratio of the ambipolar diffusion time to the free fa...

In this work gravitational collapse of a spherical cloud, consists of both dark matter and dark energy in the form of modified Chaplygin gas is studied. It is found that dark energy alone in the form of modified Chaplygin gas forms black hole. Also when both components of the fluid are present then the collapse favors the formation of black hole in cases the dark energy dominates over dark matt...

A thermodynamical description for the quasi-static collapse of radiating, self-gravitating spherical shells of matter in anti-de Sitter space-time is obtained. It is shown that the specific heat at constant area and other thermodynamical quantities may diverge before a black hole has eventually formed. This suggests the possibility of a phase transition occurring along the collapse process. The...

We generalize the spherical collapse model for the formation of bound objects to apply in a Universe with cosmological constant and quintessence. We calculate the critical condition for collapse of an overdense region and give exact values of the characteristic densities and redshifts of its evolution. We apply the results to calculate the mass function of bound objects. Comparison with the dat...