We examine the propagation of two-dimensional relativistic jets through the stellar progenitor in the collapsar model for gamma-ray bursts (GRBs). Each jet is parameterized by a radius where it is introduced, and by its initial Lorentz factor, opening angle, power, and internal energy. In agreement with previous studies, we find that relativistic jets are collimated by their passage through the...

In supersonic-combustion ramjets (scramjets), fuel is injected, which should mix rapidly with the supersonic crossflow to minimize length of scramjet. Tandem dual-jet injection has shown improved mixing performance over single-jet injection. However, experiments on tandem have not addressed jet shear layer, in occurs, yet. The present study investigates as well bow shocks front jets, a continuo...

We present polarimetric 5 GHz to 43 GHz VLBI observations of the BL Lacertae object PKS 0735+178, spanning March 1996 to May 2000. Comparison with previous and later observations suggests that the overall kinematic and structural properties of the jet are greatly influenced by its activity. Time intervals of enhanced activity, as reported before 1993 and after 2000 by other studies, are followe...

In regard to the problem of aircraft noise mitigation, the present study focuses on the refraction effects to be possibly induced by anechoic facility jet flows on the measured acoustic signatures, during typical airframe noise experiments. To this end, Computational AeroAcoustics (CAA) calculations based on the solving of the Perturbed Euler Equations (PEE) are conducted, enabling the estimati...

Adjunctive local anesthetic techniques and their armamentaria, such as intraosseous injection, computer-controlled delivery systems, periodontal ligament injection and needleless jet injection, have been proposed to hold particular advantages over conventional means of achieving local anesthesia. This article describes the use of each technique and proprietary armamentarium and reviews the lite...

Two-phase flow instability in microchannel flow boiling exhibits pressure fluctuations with different frequencies and amplitudes. One possible way to suppress the dynamic instability is to introduce synthetic jet near the inlet of the channel. An important feature of synthetic jet is that it allows momentum transfer into the microchannel flow without net mass injection into it. The strength and...

The polarization curve of GRB 020813 is discussed and compared to different models for the structure, evolution and magnetisation properties of the jet and the interstellar medium onto which the fireball impacts. GRB 020813 is best suited for this kind of analysis for the smoothness of its afterglow light curve, ensuring the applicability of current models. The polarization dataset allows us to...

A synthetic jet is formed as a consequence of a periodic – say sinusoidal – expulsion and extraction of fluid through an orifice, so that the time-averaged flow rate through the orifice is zero. Despite the zero mean mass flux, the sequence of injection followed by suction results in net momentum and vorticity being released into the fluid body in which the jet is generated. This is, essentiall...