Transport d'un scalaire passif dans une turbulence magnétohydrodynamique

Notre étude est consacrée à la simulation numérique d'une turbulence homogène évoluant sans gradient de vitesse moyenne soumise à l'action d'un champ magnétique statique. Cette simulation montre que la force de Laplace a deux effets,un effet dissipatif et un effet structural.Dans la deuxième partie,nous avons simuler numériquement une turbulence hydrodynamique cisaillée.En présence d'un cisaillement fort,le flux turbulent est pratiquement concentré dans la direction de l'écoulement moyen.Lorsque la turbulence est sujette à un champ magnétique extérieur,deux régimes sont distingués

Thermal conduction effects on the accretion-ejection mechanism. Outflow process investigation

Astrophysical jets emanating from different systems are one of the most spectacular and enigmatic phenomena pervading the Universe. These jets are typically bipolar and span hundreds of thousands of light years, some even longer than the diameter of our Milky Way. The study of the disc-jet systems is motivated by the observed correlation between ejection and accretion signatures and is still under debate. It was shown in our previous work the crucial role of thermal conduction in the dynamics of a thin viscous resistive accretion disc orbiting a central object and was provided an unprecedented wealth of discussion that has advanced our understanding of the inflow process. In this work, we expand our exploration by addressing the most outstanding basic questions concerning the launching, acceleration, and collimation processes of the jet in presence of thermal conduction. We also tackle in depth-analysis the effects of this physical ingredient on the time evolution of temperature and on mass fluxes such as inflow and outflow rates. We performed a series of 2.5-dimensional non-relativistic time-dependent numerical calculations of a disc-jet system using the PLUTO code. Our results revealed compelling evidence that thermal conduction contributes to launching a faster and more collimated jet. The mass extracted from the disc via the outflow channel is also affected by the presence of thermal conduction in the sense that the ejection efficiency is significantly improved

Extra‐gonadal mature teratoma: A case report of retroperitoneal location with a literature review

Abstract Extra‐gonadal mature teratoma is a benign tumor occurring rarely in adults. The retroperitoneal localization constitutes less than 4%. Treatment consists of surgical resection. Histological examination is essential for definitive diagnosis. We reported an unusual case of mature retroperitoneal teratoma discovered in a young man with abdominal pain