Related papers: Numerical modeling of the wind flow over a transve…
We study the hydrodynamical behavior occurring in the turbulent interaction zone of a fast moving red supergiant star, where the circumstellar and interstellar material collide. In this wind-interstellar medium collision, the familiar bow…
We study the evolution of turbulence in the solar wind by solving numerically the full 3D magneto-hydrodynamic (MHD) equations embedded in a radial mean wind. The corresponding equations (expanding box model or EBM) have been considered…
Fluctuations in the flow velocity and magnetic fields are ubiquitous in the Solar System. These fluctuations are turbulent, in the sense that they are disordered and span a broad range of scales in both space and time. The study of solar…
We perform numerical simulations to investigate the stellar wind from interacting binary stars. Our aim is to find analytical formulae describing the outflow structure. In each binary system the more massive star is in the asymptotic giant…
This paper looks into various aspects brought to light by numerical work on the generalized interacting winds model for planetary nebulae. First, a detailed comparison between radiative and non-radiative models is made, showing that one's…
Wind shear measured by Doppler tracking of the Huygens probe is evaluated, and found to be within the range anticipated by pre-flight assessments (namely less than two times the Brunt-Vaisala frequency). The strongest large-scale shear…
Turbulence plays an important role in shaping the interstellar medium, and strongly influences star formation. We aim to identify the physical processes capable of sustaining HI turbulence in the solar neighborhood. We compare recent HI…
We present one-dimensional, time-dependent models of the clumps generated by the line-deshadowing instability. In order to follow the clumps out to distances of more than 1000 stellar radii, we use an efficient moving-box technique. We show…
We investigate the bulldozing motion of a granular sandpile driven forwards by a vertical plate. The problem is set up in the laboratory by emplacing the pile on a table rotating underneath a stationary plate; the continual circulation of…
The effects of turbulence on the mixing of gases and dust in the outer Solar nebula are examined using 3-D MHD calculations in the shearing-box approximation with vertical stratification. The turbulence is driven by the magneto-rotational…
The orbital evolution of a dust particle captured in a mean motion resonance with a planet in circular orbit under the action of the Poynting-Robertson effect, radial stellar wind and an interstellar gas flow of is investigated. The secular…
We analyse the flow curves of a two-dimensional assembly of granular particles which are interacting via frictional contact forces. For packing fractions slightly below jamming, the fluid undergoes a large scale instability, implying a…
The solar wind speed at 1 AU shows variations in latitude and in time which reflect the evolution of the global background magnetic field during the activity cycle. It is commonly accepted that the terminal wind speed in a magnetic…
We study line driven stellar winds using time-dependent radiation hydrodynamics where the continuum radiation couples to the gas via either a scattering or absorption opacity and there is an additional radiation force due to spectral lines…
The distances to individual wind-driven bubbles such as Planetary Nebulae (PNe) can be determined using expansion parallaxes: the angular expansion velocity in the sky is compared to the radial velocity of gas measured spectroscopically.…
The vectoral wind structure of daytime atmospheric boundary layer (ABL) turbulence is strongly dependent on the balance between shear-driven turbulence production of horizontal fluctuations (driven by winds at the mesoscale), and…
The dependence of the barchan dune dynamics on the size of the grains involved is investigated experimentally. Downsized barchan dune slices are observed in a narrow water flow tube. The relaxation time from an initial symmetric triangular…
It is widely accepted that both ripples and dunes form in rivers by primary linear instability, the wavelength of the former scaling on the grain size, that of the latter being controled by the water depth. We revisit here this problem,…
We have experimentally investigated 2-dimensional dense bubble flows underneath inclined planes. Velocity profiles and velocity fluctuations have been measured. A broad second-order phase transition between two dynamical regimes is observed…
We investigate the propagation of high-speed solar wind streams from their origin near the Sun to 1 AU using three-dimensional magnetohydrodynamic simulations. By tracking both global stream structure and individual plasma parcels, we…