The Lighthill acoustic analogy indicates that substantial noise reduction is possible in high-speed jets by reducing the radiation efficiency. This entails reducing the convective Mach number of the eddies whose footprint is sensed in the near pressure field. In dualstream jets, local reduction in convective Mach number is possible by inducing asymmetry in the plume that redistributes the most ...

Context. Previous molecular gas observations at arcsecond-scale resolution of the Seyfert 2 galaxy M51 suggest the presence of a dense circumnuclear rotating disk, which may be the reservoir for fueling the active nucleus and obscures it from direct view in the optical. However, our recent interferometric CO(3-2) observations show a hint of a velocity gradient perpendicular to the rotating disk...

Recently Hardcastle & Worrall (2000) analyzed 63 FRII radio galaxies imbedded in the X-ray radiating gas in galaxy clusters and concluded, that pressures inside its lobes seem to be a factor of a few lower than in the surrounding gas. One of explanations of the existing ‘blown up’ radio lobes is the existence of invisible internal pressure component due to energetic cosmic ray nuclei (protons)....

A Proper Orthogonal Decomposition (POD) is constructed for a Mach 0.9 turbulent jet using a well-validated direct numerical simulation database. Norms are defined based on near-field volume integrals of pressure, turbulence kinetic energy, streamwise velocity, and total enthalpy, two-dimensional integrals of streamswise velocity (to match experimental measurements), and far-field integrals of p...

many experimental studies have been conducted on development of the scour hole as a result of vertical jet impaction. research has shown that aeration of the nappe flow in the model is much weaker than that in the prototype. therefore, the influence of aeration on scour holes needs further study. experimental investigation of the effects of air entrainment and tail water depth on the scour hole...

This paper presents an original experimental and numerical investigation of acoustic streaming driven by an acoustic beam reflecting on a wall. The water experiment features a 2 MHz acoustic beam totally reflecting on one of the tank glass walls. The velocity field in the plane containing the incident and reflected beam axes is investigated using Particle Image Velocimetry (PIV). It exhibits an...

The kinematic and radiative power of molecular jets is expected to change as a protostar undergoes permanent or episodal changes in the rate at which it accretes. We study here the consequences of evolving jet power on the spatial and velocity structure, as well as the fluxes, of molecular emission from the bipolar outflow. We consider a jet of rapidly increasing density and a jet in which the ...

The overall properties of the Herbig–Haro objects such as centerline velocity, transversal profile of velocity, flow of mass, and flow of energy are explained adopting two models for the turbulent jet. The complex shapes of the Herbig–Haro objects, such as the arc in HH34, can be explained by introducing the combination of different kinematic effects such as velocity behavior along the main dir...

abstract in this study, the effect of suspended load transport on the characteristics of submerged hydraulic jump (shj) in a rectangular channel was investigated experimentally. sediment concentration and jet froude numbers in the range of 0.424%-16.15% and 1.93-4.96, respectively, were considered. tow grain size 0.15 and 0.03 mm were used in the experiments. characteristics of submerged hydrau...

Results of spectroscopy of unusual symbiotic variable star MWC560 are presented. The data have been obtained from autumn 1990 to spring 1993. High velocity absorption lines of H I, D1 D2 Na I, Fe II(42) and He I are permanently presented in the spectra, their radial velocity is −500 ÷ −2500 km/s and is changed with a time–scale of a few months. The high velocity absorption line profiles demonst...