Effect of Initial Disturbance on The Detonation Front Structure of a Narrow Duct

The effect of an initial disturbance on the detonation front structure in a narrow duct is studied by three-dimensional numerical simulation. The numerical method used includes a high resolution fifth-order weighted essentially non-oscillatory scheme for spatial discretization, coupled with a third order total variation diminishing Runge-Kutta time stepping method. Two types of disturbances are used for the initial perturbation. One is a random disturbance which is imposed on the whole area of the detonation front, and the other is a symmetrical disturbance imposed within a band along the diagonal direction on the front. The results show that the two types of disturbances lead to different processes. For the random disturbance, the detonation front evolves into a stable spinning detonation. For the symmetrical diagonal disturbance, the detonation front displays a diagonal pattern at an early stage, but this pattern is unstable. It breaks down after a short while and it finally evolves into a spinning detonation. The spinning detonation structure ultimately formed due to the two types of disturbances is the same. This means that spinning detonation is the most stable mode for the simulated narrow duct. Therefore, in a narrow duct, triggering a spinning detonation can be an effective way to produce a stable detonation as well as to speed up the deflagration to detonation transition process.Comment: 30 pages and 11 figure

Interaction of a spark-generated bubble with a rubber beam: Numerical and experimental study

In this paper, the physical behaviors of the interaction between a spark-generated bubble and a rubber beam are studied. Both numerical and experimental approaches are employed to investigate the bubble collapse near the rubber beam (which acts as a flexible boundary) and the corresponding large deformation of the beam. Good agreement between the numerical simulations and experimental observations is achieved. The analysis reveals that the ratio of the bubble-beam distance to the maximum bubble radius influences the bubble evolution (from expansion to collapse) and the beam deformation. The stiffness of the beam plays an important role in the elastic beam response to bubble expansion and collapse. The effect of the vapor pressure on both bubble collapses and beam deflections is also examined. The results from this paper may provide physical insight into the complex physics of the bubble-rubber interaction. The understanding is possibly applicable in biomedicine for drug delivery to tissue, which is a soft material. It is also probably useful in the marine industry where ultrasonic bubbles are generated for the defouling of ship surfaces, which has been coated with an elastic material. There is also potential interest in underwater explosions near elastic structures

A collapsing bubble-induced microinjector: An experimental study

10.1007/s00348-008-0568-3Experiments in Fluids463419-434EXFL

Finite element analysis of second order wave radiation by a group of cylinders in the time domain

10.1016/S1001-6058(11)60373-XJournal of Hydrodynamics253348-361JOUH

Energy gradient method for turbulent transition with consideration of effect of disturbance frequency

10.1016/S1001-6058(09)60163-3Journal of Hydrodynamics225 SUPPL. 123-28JOUH

Cerebral embolism following N-butyl-2-cyanoacrylate injection for esophageal postbanding ulcer bleed: a case report

Systemic embolization is a rare but serious complication of variceal injection with cyanoacrylate. We report a case of cerebral embolism a few hours after an injection of Histoacryl into a bleeding esophageal post-banding ulcer. Echocardiogram revealed patent foramen ovale