32 research outputs found
Experimental two dimensional cellular flames
International audienceThe propagation of very unstable cellular flames (also called self-turbulent flames) is studied experimentally in a Hele-Shaw cell. This quasi-two dimensional configuration allows for quantitative image analysis. The dynamics of the premixed flame is controlled in these conditions by the creation or merging of the cusps that appear on the front
Differential diffusion effects on buoyancy-driven instabilities of acid-base fronts: The case of a color indicator
Buoyancy-driven hydrodynamic instabilities of acid-base fronts are studied both experimentally and theoretically in the case where an aqueous solution of a strong acid is put above a denser aqueous solution of a color indicator in the gravity field. The neutralization reaction between the acid and the color indicator as well as their differential diffusion modifies the initially stable density profile in the system and can trigger convective motions both above and below the initial contact line. The type of patterns observed as well as their wavelength and the speed of the reaction front are shown to depend on the value of the initial concentrations of the acid and of the color indicator and on their ratio. A reaction-diffusion model based on charge balances and ion pair mobility explains how the instability scenarios change when the concentration of the reactants are varied.Fil: Kuster, S.. Universidad de Buenos Aires. Facultad de IngenierĂa. Departamento de FĂsica. Grupo de Medios Porosos; ArgentinaFil: Riolfo, L. A.. Universidad de Buenos Aires. Facultad de IngenierĂa. Departamento de FĂsica. Grupo de Medios Porosos; ArgentinaFil: Zalts, Anita. Universidad Nacional de General Sarmiento; ArgentinaFil: El Hasi, C.. Universidad Nacional de General Sarmiento; ArgentinaFil: Almarcha, C.. UniversitĂ© Libre de Bruxelles; BĂ©lgicaFil: Trevelyan, P.M.J.. UniversitĂ© Libre de Bruxelles; BĂ©lgicaFil: De Wit, A.. UniversitĂ© Libre de Bruxelles; BĂ©lgicaFil: D'onofrio, Alejandro Gustavo. Universidad de Buenos Aires. Facultad de IngenierĂa. Departamento de FĂsica. Grupo de Medios Porosos; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentin
Chemical abundances of Seyfert 2 AGNs, I: comparing oxygen abundances from distinct methods using SDSS
We compare the oxygen abundance (O/H) of the narrow-line regions (NLRs) of Seyfert 2 AGNs obtained through strong-line methods and from direct measurements of the electron temperature (Te-method). The aim of this study is to explore the effects of the use of distinct methods on the range of metallicity and on the mass-metallicity relation of active galactic nuclei (AGNs) at low redshifts (z<~0.4). We used the Sloan Digital Sky Survey (SDSS) and NASA/IPACExtragalactic Database (NED) to selected optical (3000Fil: Dors, Oli L.. Universidade Do Vale Do Paraiba; BrasilFil: de Freitas Rosa, Morsyleide. Universidade Do Vale Do Paraiba; BrasilFil: Amores, E. B.. Universidade Estadual de Feira de Santana; BrasilFil: Almarcha PĂ©rez, Martha AyelĂ©n. Instituto de AstrofĂsica de AndalucĂa - Csic; EspañaFil: Cardaci, Monica Viviana. Instituto de AstrofĂsica de la Plata (conicet- Universidad Nacional de la Plata); Argentina. Universidad Nacional de La Plata; ArgentinaFil: Hägele, Guillermo Federico. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de AstrofĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas. Instituto de AstrofĂsica La Plata; ArgentinaFil: Armah, M.. Universidade Do Vale Do Paraiba; BrasilFil: Krabbe, A. C.. Universidade Do Vale Do Paraiba; BrasilFil: Ruiz FaĂşndez, Giovanni Patricio. Laboratorio Nacional de Astrofisica, Itajuba; Brasi
Nonlinear dynamics of premixed flames: from deterministic stages to stochastic influence
International audienceAbstrac