Numerical calculation of subsonic jets in crossflow with reduced numerical diffusion

A series of calculations are reported for two, subsonic jet in crossflow geometries. The parametric variation examined are the lateral spacing of a row of jets. The first series of calculations corresponds to a widely space jet geometry, S/D = 4, and the second series corresponds to closely spaced jets, S/D = 2. The calculations are done with alternate differencing schemes to illustrate the impact of numerical diffusion. The calculated jet trajectories agreed well with experimental data in the widely spaced jet geometry, but not in the closely spaced geometry

Graded Jet Geometry

Jet manifolds and vector bundles allow one to employ tools of differential geometry to study differential equations, for example those arising as equations of motions in physics. They are necessary for a geometrical formulation of Lagrangian mechanics and the calculus of variations. It is thus only natural to require their generalization in geometry of $\mathbb{Z}$-graded manifolds and vector bundles. Our aim is to construct the $k$-th order jet bundle $\mathfrak{J}^{k}_{\mathcal{E}}$ of an arbitrary $\mathbb{Z}$-graded vector bundle $\mathcal{E}$ over an arbitrary $\mathbb{Z}$-graded manifold $\mathcal{M}$. We do so by directly constructing its sheaf of sections, which allows one to quickly prove all its usual properties. It turns out that it is convenient to start with the construction of the graded vector bundle of $k$-th order (linear) differential operators $\mathfrak{D}^{k}_{\mathcal{E}}$ on $\mathcal{E}$. In the process, we discuss (principal) symbol maps and a subclass of differential operators whose symbols correspond to completely symmetric $k$-vector fields, thus finding a graded version of Atiyah Lie algebroid. Necessary rudiments of geometry of $\mathbb{Z}$-graded vector bundles over $\mathbb{Z}$-graded manifolds are recalled

Direct measurement of the jet geometry in Seyfert galaxies

We demonstrate that, by combining optical, radio and X-ray observations of a Seyfert, it is possible to provide a direct measurement of the angle $\beta$ between the direction of the radio jet and the normal to the plane of the spiral host galaxy. To do so, we make the assumptions that the inner radio jet is perpendicular to the X-ray observed inner accretion disk, and that the observed jet (or the stronger component, if the jet is two-sided) is physically closer to Earth than the plane of the galaxy. We draw attention to the possibility of measurement producing a result which is not self-consistent, in which case for that galaxy, one of the assumptions must fail.Comment: 11 pages, 1 figure, accepted for publication in The Astrophysical Journal Letter

The JetCurry Code. I. Reconstructing Three-Dimensional Jet Geometry from Two-Dimensional images

We present a reconstruction of jet geometry models using numerical methods based on a Markov ChainMonte Carlo (MCMC) and limited memory Broyden-Fletcher-Goldfarb-Shanno (BFGS) optimized algorithm. Our aim is to model the three-dimensional geometry of an AGN jet using observations, which are inherently two-dimensional. Many AGN jets display complex hotspots and bends over the kiloparsec scales. The structure of these bends in the jets frame may be quite different than what we see in the sky frame, transformed by our particular viewing geometry. The knowledge of the intrinsic structure will be helpful in understanding the appearance of the magnetic field and hence emission and particle acceleration processes over the length of the jet. We present the method used, as well as a case study based on a region of the M87 jet.Comment: Submitted to ApJ on Feb 01, 201

Gamma-Ray Bursts: Jets and Energetics

The relativistic outflows from gamma-ray bursts are now thought to be narrowly collimated into jets. After correcting for this jet geometry there is a remarkable constancy of both the energy radiated by the burst and the kinetic energy carried by the outflow. Gamma-ray bursts are still the most luminous explosions in the Universe, but they release energies that are comparable to supernovae. The diversity of cosmic explosions appears to be governed by the fraction of energy that is coupled to ultra-relativistic ejecta.Comment: Paper presented at "The Restless High-Energy Universe", May 5-8 2003 Royal Tropical Institute, Amsterda

Primjena IC termografije za određivanje geometrije istrujnog mlaza u KGHV sustavima

A properly designed room air diffusion scheme ensures that when conditioned air is supplied into a room, it causes no discomfort to the occupants. To confirm the design characteristic of an air diffusion arrangement a measurement of different parameters of air movement pattern like jet geometry, air temperature and velocity or humidity must be done. IR thermography can be successfully applied for quick determination of the air jet geometry, not only for new and existing systems, but also in the design phase of air inlets and outlets. The paper presents the possibilities for the determination of jet geometry, radius and spread by means of IR thermography.Ispravno projektiran sustav za distribuciju zraka u prostoriji osigurava stanje ugode osobama koji u njoj borave. Da bi se potvrdili parametri koji karakteriziraju tu distribuciju, potrebno je izvršiti određena mjerenja poput geometrije mlaza, temperature, brzine i vlažnosti zraka koji se ubacuje u prostor. IC termografija se može uspješno primijeniti ne samo za brzo određivanje mlaza kod novih i postojećih sustava već i kod konstruiranja usisnih i odsisnih elemenata. Radom su prikazane mogućnosti određivanja geometrije mlaza kao što su domet i širina upotrebom IC termografije

Primjena IC termografije za određivanje geometrije istrujnog mlaza u KGHV sustavima

A properly designed room air diffusion scheme ensures that when conditioned air is supplied into a room, it causes no discomfort to the occupants. To confirm the design characteristic of an air diffusion arrangement a measurement of different parameters of air movement pattern like jet geometry, air temperature and velocity or humidity must be done. IR thermography can be successfully applied for quick determination of the air jet geometry, not only for new and existing systems, but also in the design phase of air inlets and outlets. The paper presents the possibilities for the determination of jet geometry, radius and spread by means of IR thermography.Ispravno projektiran sustav za distribuciju zraka u prostoriji osigurava stanje ugode osobama koji u njoj borave. Da bi se potvrdili parametri koji karakteriziraju tu distribuciju, potrebno je izvršiti određena mjerenja poput geometrije mlaza, temperature, brzine i vlažnosti zraka koji se ubacuje u prostor. IC termografija se može uspješno primijeniti ne samo za brzo određivanje mlaza kod novih i postojećih sustava već i kod konstruiranja usisnih i odsisnih elemenata. Radom su prikazane mogućnosti određivanja geometrije mlaza kao što su domet i širina upotrebom IC termografije