The Hα velocity fields of a sample of six luminous blue compact galaxies (BCGs) and two companions have been obtained by observations with a scanning Fabry-Perot interferometer. The Fabry-Perot images, velocity fields and rotations curves have been presented in a previous paper (Paper I). In general, the velocity fields are irregular and often contain secondary dynamical components, but display...

Aims. We present a new formal solution of the Lagrangian equation of radiative transfer that is useful in solving the equation of radiative transfer in the presence of arbitrary velocity fields. Methods. Normally a term due to the inclusion of the wavelength derivative in the Lagrangian equation of radiative transfer is associated with a generalised opacity. In non-monotonic velocity fields, th...

In this paper we test the results of a recent analytical study by Lazarian and Pogosyan, on the statistics of emissivity in velocity channel maps, in the case of realistic density and velocity fields obtained from numerical simulations of MHD turbulence in the interstellar medium (ISM). To compensate for the lack of well-developed inertial ranges in the simulations due to the limited resolution...

The velocity and other fields of steady two-dimensional surface gravity waves in irrotational motion are investigated numerically. Only symmetric waves with one crest per wavelength are considered, i.e. Stokes waves of finite amplitude, but not the highest waves, nor subharmonic and superharmonic bifurcations of Stokes waves. The numerical results are analysed, and several conjectures are made ...

Semi-geostrophic dynamics of jets are studied using a potential vorticity front in an equivalent barotropic model. Meandering processes of the front are examined in the thin-jet limit on a β-plane by a curvilinear coordinate system. For calculated along-front velocity fields, asymmetrical profiles are caused by meandering. This asymmetry of the velocity profile is enhanced as the Rossby number ...

A PIV algorithm is presented for estimating time-averaged or phase-averaged velocity fields. The algorithm can be applied to situations where signal strength is not sufficient for standard cross correlation techniques, such as a low number of particle images in an interrogation spot, or poor image quality. The algorithm can also be used to increase the spatial resolution of measurements by allo...

In this paper we study homogenization of nonlinear hyperbolic equations. The weak limit of the solutions is investigated by approximating the flux functions with piecewise linear functions. We study mostly Riemann problems for layered velocity fields as well as for the heterogeneous divergence free velocity fields.

Observations of six luminous blue compact galaxies (BCGs) and two star forming companion galaxies were carried out with the CIGALE scanning Fabry-Perot interferometer attached to the ESO 3.6m telescope on La Silla. The observations were made in the Hα emission line which is prominent in BCGs. A velocity sampling of 5 km/s and a pixel size of 0.9 arcseconds were used. In this paper we present th...

A one dimensional non-linear magnetohydrodynamic (MHD) system has been introduced to test a sequential optimal interpolation assimilation technique that uses a Monte-Carlo method to calculate the forecast error covariance. An ensemble of 100 model runs with perturbed initial conditions are used to construct the covariance, and the assimilation algorithm is tested using Observation Simulation Ex...

The concept of flow field velocimetry based on scalar imaging measurements @Phys. Fluids A 4, 2191 ~1992!# is here formulated in terms of an integral minimization implementation, where the velocity field u~x,t! is found by minimizing weighted residuals of the conserved scalar transport equation, along with the continuity condition and a smoothness condition. We apply this technique to direct nu...