Réponse au commentaire de Brahim Akdim et Ramón Julia sur la note Datation par la méthode U/Th d'un travertin quaternaire du Sud-Est marocain : implications paléoclimatiques pendant le Pléistocène moyen et supérieur [C. R. Geoscience 335 (2003) 469–478]     

Larbi Boudad  Lahcen Kabiri  Samer Farkh  Christophe Falguères  Louis Rousseau  Jacques Beauchamp  Élisabeth Nicot  Guillaume Cairanne 《Comptes Rendus Geoscience》2006,338(8):583

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Dynamical friction in an isentropic gas     

Fazeleh Khajenabi  Sami Dib 《Astrophysics and Space Science》2012,340(1):117-125

When a gravitating object moves across a given mass distribution, it creates an overdense wake behind it. Here, we performed an analytical study of the structure of the flow far from object when the flow is isentropic and the object moves subsonically within it. We show that the dynamical friction force is the main drag force on the object and by using a perturbation theory, we obtain the density, velocity and pressure of the perturbed flow far from the mass. We derive the expression of the dynamical friction force in an isentropic flow and show its dependence on the Mach number of the flow and on the adiabatic index. We find that the dynamical friction force becomes lower as the adiabatic index increases. We show analytically that the wakes are less dense in our isentropic case in comparison to the isothermal ones.  相似文献