scholarly journals Fabry-Perot Observations and Hydrodynamical Simulations of the Barred Spiral NGC 4123

1996 ◽  
Vol 157 ◽  
pp. 489-491 ◽  
Author(s):  
Benjamin J. Weiner ◽  
J. A. Sellwood ◽  
T. B. Williams
Keyword(s):  
Velocity Field ◽  
Gas Flow ◽  
Semimajor Axis ◽  
Lagrange Point ◽  
Model Potentials ◽  
Fabry Perot ◽  
Correct Alignment ◽  
Pattern Speed ◽  
Leading Edges ◽  
Hydrodynamical Simulations

AbstractWe present Fabry-Perot observations of the velocity field of gas in the barred spiral NGC 4123, and 2-D hydrodynamical simulations of the gas flow in model potentials derived from I-band photometry. The simulated gas flow is quite sensitive to the details of the potential, which enables us to constrain parameters such as the M/LI of the bar and the bar pattern speed. The observations confirm that the dust lanes along the leading edges of the bar are the locations of shocks. Requiring models to produce shocks with the correct alignment constrains the Lagrange point L1 (corotation) to be at a radius 1.1 – 1.4 times the semimajor axis of the bar, i.e. the bar is a fast rotator.

scholarly journals Photometry and Kinematics of the Ringed Barred Galaxy NGC 3081

1996 ◽  
Vol 157 ◽  
pp. 244-246
Author(s):  
Guy B. Purcell ◽  
R. Buta
Keyword(s):  
Velocity Field ◽  
Preliminary Analysis ◽  
Fabry Perot ◽  
The Galaxy ◽  
Pattern Speed

AbstractWe present a preliminary analysis of B- and I-band CCD images and Rutgers imaging Fabry–Perot Hα interferometry of the galaxy NGC 3081. We find that the outer R1 and inner ring are both intrinsically oval. We derive a bar pattern speed from the velocity field.

Simulation of mechanically stirred two-phase liquid-gas flow

1986 ◽  
Vol 51 (5) ◽  
pp. 1001-1015 ◽  
Author(s):  
Ivan Fořt ◽  
Vladimír Rogalewicz ◽  
Miroslav Richter
Keyword(s):  
Spatial Distribution ◽  
Velocity Field ◽  
Gas Flow ◽  
Liquid Velocity ◽  
Model Parameters ◽  
Two Phase ◽  
Mean Velocity ◽  
Rushton Turbine ◽  
Low Viscosity ◽  
Volumetric Gas Flow Rate

The study describes simulation of the motion of bubbles in gas, dispersed by a mechanical impeller in a turbulent low-viscosity liquid flow. The model employs the Monte Carlo method and it is based both on the knowledge of the mean velocity field of mixed liquid (mean motion) and of the spatial distribution of turbulence intensity ( fluctuating motion) in the investigated system - a cylindrical tank with radial baffles at the wall and with a standard (Rushton) turbine impeller in the vessel axis. Motion of the liquid is then superimposed with that of the bubbles in a still environment (ascending motion). The computation of the simulation includes determination of the spatial distribution of the gas holds-up (volumetric concentrations) in the agitated charge as well as of the total gas hold-up system depending on the impeller size and its frequency of revolutions, on the volumetric gas flow rate and the physical properties of gas and liquid. As model parameters, both liquid velocity field and normal gas bubbles distribution characteristics are considered, assuming that the bubbles in the system do not coalesce.

scholarly journals Halo cluster shapes: insights from simulated galaxies and ICL with prospects for weak lensing applications

2021 ◽  
Vol 508 (1) ◽  
pp. 1280-1295
Author(s):  
Elizabeth J Gonzalez ◽  
Cinthia Ragone-Figueroa ◽  
Carlos J Donzelli ◽  
Martín Makler ◽  
Diego García Lambas ◽  
...  
Keyword(s):  
Observational Studies ◽  
Semimajor Axis ◽  
Galaxy Cluster ◽  
Weak Lensing ◽  
Cluster Galaxy ◽  
Surface Mass ◽  
Cluster Shape ◽  
The Galaxy ◽  
Hydrodynamical Simulations ◽  
Intracluster Light

ABSTRACT We present a detailed study of the shapes and alignments of different galaxy cluster components using hydrodynamical simulations. We compute shape parameters from the dark matter (DM) distribution, the galaxy members and the intracluster light (ICL). We assess how well the DM cluster shape can be constrained by means of the identified galaxy member positions and the ICL. Further, we address the dilution factor introduced when estimating the cluster elongation using weak-lensing stacking techniques, which arises due to the misalignment between the total surface mass distribution and the distribution of luminous tracers. The dilution is computed considering the alignment between the DM and the brightest cluster galaxy, the galaxy members and the ICL. Our study shows that distributions of galaxy members and ICL are less spherical than the DM component, although both are well aligned with the semimajor axis of the latter. We find that the distribution of galaxy members hosted in more concentrated subhaloes is more elongated than the distribution of the DM. Moreover, these galaxies are better aligned with the DM component compared to the distribution of galaxies hosted in less concentrated subhaloes. We conclude that the positions of galaxy members can be used as suitable tracers to estimate the cluster surface density orientation, even when a low number of members is considered. Our results provide useful information for interpreting the constraints on the shapes of galaxy clusters in observational studies.

scholarly journals The Velocity Field of S308. The Ring Nebula Around the WN5 Star HD 50896

1982 ◽  
Vol 99 ◽  
pp. 305-309
Author(s):  
Paris Pişmiş ◽  
Alfonso Quintero
Keyword(s):  
Velocity Field ◽  
Radial Velocities ◽  
Expansion Velocity ◽  
Ring Nebula ◽  
Fabry Perot

Radial velocities are determined by Fabry-Pérot interferometry at 131 points of the ring nebula S308. The velocities have yielded a kinematic distance of 1.5 kpc for the object, and an expansion velocity of 45–60 km s−1. The ring nebula has a diameter of 13 pc and the age is estimated to be about 1.5 to 2×105 years.

scholarly journals Investigation of flow kinematics in the structured multibed catalytic cartridge

2019 ◽  
Vol 196 ◽  
pp. 00058
Author(s):  
Diana Ezendeeva ◽  
Sergei Kakaulin ◽  
Maxim Gordienko ◽  
Ivan Kabardin
Keyword(s):  
Volatile Organic Compounds ◽  
Velocity Field ◽  
Velocity Profile ◽  
Organic Compounds ◽  
Energy Efficient ◽  
Gas Flow ◽  
Laser Doppler Anemometry ◽  
Volatile Organic ◽  
Harmful Substances ◽  
Flow Distributor

The reduction of harmful substances emission into the atmosphere is very important to create compact, energy-efficient catalytic units for afterburning volatile organic compounds. A key component of such units is the catalyst cartridge. The efficiency of its operation is provided by the supply of a gas flow with a uniform velocity field. To solve the problem, the gas flow distributor and an aerodynamic stand for its testing were created. A set of air-flow blades was used to align the velocity profile before the catalyst cartridge. Also flow kinematics inside the cartridge was investigated via laser Doppler anemometry method.

scholarly journals Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 1365

1996 ◽  
Vol 157 ◽  
pp. 413-415
Author(s):  
P. A. B. Lindblad ◽  
P. O. Lindblad ◽  
E. Athanassoula
Keyword(s):  
Gravitational Field ◽  
Gas Dynamics ◽  
Rotation Curve ◽  
Barred Galaxies ◽  
Mosaic Image ◽  
Dynamical Parameters ◽  
Pattern Speed ◽  
Barred Spiral Galaxy ◽  
Hydrodynamical Simulations ◽  
Ngc 1365

Several authors have explored the field of gas dynamics in barred systems. One of the aims of these investigations was to compare the model gaseous response, due to some assumed underlying stellar gravitational field, with observed gas density distribution and kinematics of barred galaxies. The gas is known to respond in a highly non-linear way, and therefore should give clues to dynamical parameters like the mass distribution, positions and existence of principal resonances and thereby the pattern speed.High resolution HI data now exist for NGC 1365 (Jörsäter & van Moorsel 1995), and the kinematical HI data have been combined with optical long slit measurements to obtain the velocity field (Lindblad et al. 1995) used for extracting the rotation curve, representing the axisymmetric forces in NGC 1365, and for comparisons with models. A mosaic image of NGC 1365 in the J-band was used to compute the perturbing potential used in the models.

scholarly journals The Structure and Velocity Field of A78

1989 ◽  
Vol 131 ◽  
pp. 185-185
Author(s):  
P. Pismis ◽  
M. A. Moreno
Keyword(s):  
Velocity Field ◽  
Planetary Nebula ◽  
Image Intensifier ◽  
Radial Velocities ◽  
Central Hole ◽  
Expansion Velocity ◽  
San Pedro ◽  
Systemic Velocity ◽  
Fabry Perot ◽  
The Face

We present a velocity field of the planetary nebula A78 based on three Fabry Pérot Hα (10A) interferograms taken with a focal reducer attached to the 2.1 m reflector of the Observatorio Astronómico Nacional at San Pedro Mártir, Mexico. We have used a single-stage Varo image intensifier and two different étalons with interorder separations of 283 km s−1 (2 interf.) and 100 km s−1 (1 interf.). The scale of the original photographs is 49 arcsec mm−1. Our data have yielded radial velocities in the Hα line at 110 points on the face of A78; the velocity field is far from being smooth. The rings are wide around the central hole, and a few show definite splittings; from these splittings we have estimated an overall expansion velocity of 27 km s−1. The average systemic velocity is found to be around −3 km s−1.

scholarly journals 6.5. Hydrodynamical simulations as probes for the structure of the galactic center

1998 ◽  
Vol 184 ◽  
pp. 271-272
Author(s):  
K. Wada ◽  
T. Minezaki ◽  
K. Sakamoto ◽  
H. Fukuda
Keyword(s):  
Numerical Modeling ◽  
Numerical Simulations ◽  
Mass Distribution ◽  
Galactic Center ◽  
Dynamical Behavior ◽  
Interstellar Gas ◽  
Interstellar Gas In Galaxies ◽  
Dynamical Parameters ◽  
Pattern Speed ◽  
Hydrodynamical Simulations

Numerical modeling of the interstellar gas in galaxies is an effective approach to infer galactic gravitational structure. This is because the dynamical behavior of gas is very sensitive to the background gravitational potential. Since the dynamical resonances depend closely on the mass distribution and the pattern speed of the non-axisymmetric component, it is possible to determine these dynamical parameters by comparison of numerical simulations and gas observations.

Pebble accretion onto planets in turbulent discs

2018 ◽  
Vol 14 (S345) ◽  
pp. 237-238
Author(s):  
Wilhelm Kley ◽  
Giovanni Picogna ◽  
Moritz H. R. Stoll
Keyword(s):  
Gas Flow ◽  
Mass Range ◽  
Shear Instability ◽  
Accretion Discs ◽  
Vertical Shear ◽  
Turbulent Motion ◽  
Hydrodynamic Drag ◽  
Embedded Particles ◽  
Hydrodynamical Simulations

AbstractPlanets form in protoplanetary accretion discs around young protostars. These discs are driven by internal turbulence and the gas flow is not laminar but has stochastic components. For weakly ionised discs the turbulence can be generated purely hydrodynamically through the vertical shear instability (VSI). Embedded particles (dust/pebbles) experience a hydrodynamic drag and drift inward radially and are stirred up vertically by the turbulent motion of the disc. We study the accretion of particles onto a forming planet embedded in a VSI turbulent protoplanetary disc through a series of 3D hydrodynamical simulations for locally isothermal discs with embedded planets in the mass range from 5 to 100 Earth masses (M2295).

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