DITF - MF - Comunicaciones en Congresos y otros eventos
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Publication Impact induced motion of boulders and their effect on ejecta emplacement on rubble-pile targets(Europlanet Society, 2022) Ormö, Jens; Raducan, Sabina D.; Luther, Robert; Jutzi, Martin; Herreros Cid, María Isabel; Collins, Gareth; Wünnemann, Kai; Mauri, Valentin; European Commission; Agencia Estatal de Investigación (España)Asteroids smaller than about 50 km in diameter are the result of the break-up of a larger parent body. They are often considered to be rubble-pile objects, aggregates held together only by self-gravity or small cohesive forces, and have highly heterogeneous surfaces. Recently, the artificial impact experiment (SCI) of JAXA's Hayabusa2 mission on the surface of asteroid Ryugu created a relatively large crater (~14 m diameter) despite the presence of large boulders close to the impact location...Publication Modeling the origin of Río Tinto(Europlanet Society, 2022) Herreros Cid, María Isabel; Escudero, Cristina; Gómez-Ortiz, David; Rodríguez, Nuria; Martínez, Aitor; Suarez-Gordo, Alejandro; Fernández-Remolar, David; Gómez, Felipe; Amils, Ricardo; Ministerio de Ciencia e Innovación (España)Publication Effects of target heterogeneity on impact cratering processes in the light of the Hera mission: combined experimental and numerical approach(Copernicus Publications, 2020-09-21) Ormö, Jens; Raducan, Sabina D.; Luther, Robert; Herreros Cid, María Isabel; Collins, Gareth S.; Losiak, Ania; Wünnemann, Kai; Ministerio de Ciencia e Innovación (España)The Double Asteroid Redirection Test (DART) plans to impact the smaller component of the 65803 Didymos asteroid system [1], Dimorphos, and alter the binary orbit period of the system [2]. The experiment aims to demonstrate the controlled deflection capabilities of a near-Earth asteroid. ESA’s Hera mission [1,2] will arrive at Dimorphos four years after the DART impact and provides a detailed characterization of the impact. For a successful analysis it is important to know the influence of various parameters known to affect the cratering. Here we present some preliminary results as well as planned experiments at the Experimental Projectile Impact Chamber (EPIC) at Centro de Astrobiología CSIC-INTA, Spain, carried out in concert with observations of natural craters and numerical simulations for mutual verification of the methods and a first analysis of the effects of factors such as heterogeneities in a granular (i.e. ‘rubble-pile’) target.Publication A method to assess event magnitude and target water depth for marine-target impacts. Part 2: The physics behind the observations(Copernicus Publications, 2020-09-21) Herreros Cid, María Isabel; Örmo, Jens; Ministerio de Ciencia e Innovación (España)We present a mathematical model for the study of the aquatic settling process of resurge sediments after a marine-target impact with cratering of the seafloor. Fragments from the solid target are mixed with the seawater. After an initial turbulent phase the suspended solid particles begin to settle. Previous studies of resurge sediments in drill cores from several craters indicate a relationship between the sedimentology, the target water depth, and the magnitude of the event [1]. Here we investigate the physics behind the relationship.Publication Modeling of fluvial episodic events at a channel in Nepenthes Mensae region of Mars(Copernicus Publications, 2022-09-18) Molina, Antonio; De Pablo, Miguel Angel; Herreros Cid, María Isabel; Pertuz Dominguez, Alejandro; Roldan Casaelles, Guillermo; Martinez, Andrea; Ministerio de Ciencia e Innovación (España)Publication An experimental and numerical study of flames in narrow channels with electric fields(Institute of Physics Publishing, 2014-11-18) Murphy, Daniel C.; Sánchez-Sanz, Mario; Fernández Pello, CarlosThe advancement of microscale combustion has been limited by quenching effects as flames cease to be much smaller than combustors. The long studied sensitivity of flames to electrical effects may provide means to overcome this issue. Here we experimentally and numerically investigate the potential of electric field effects to enhance combustion. The results demonstrate that, under specific conditions, externally electric fields will sustain combustion in structures smaller than the quenching distance. The analysis proposes a reduced mechanism to model this result and provides a study of the governing parameters. We find good qualitative agreement between the model and experiments. Specifically, the model is found to successfully capture the capacity to increase and decrease flame speed according to electric field magnitude and direction. Further, in both experiments and computations the sensitivity to electrical enhancement increases for more energetic mixtures. We do find that the model underpredicts the maximum achievable speed enhancement observed, suggesting that additional phenomena should be included to expand the range of conditions that can be studied.Publication Flammability conditions for ultra-lean hydrogen premixed combustion based on flame-ball analyses(Elsevier, 2012-01) Fernández Tarrazo, Eduardo Antonio; Sánchez Pérez, Antonio Luis; Williams, Forman A.; Liñán Martínez, AmableIt has been reasoned that the structures of strongly cellular flames in very lean mixtures approach an array of flame balls, each burning as if it were isolated, thereby indicating a connection between the critical conditions required for existence of steady flame balls and those necessary for occurrence of self-sustained premixed combustion. This is the starting assumption of the present study, in which structures of near-limit steady sphericosymmetrical flame balls are investigated with the objective of providing analytic expressions for critical combustion conditions in ultra-lean hydrogen-oxygen mixtures diluted with N2 and water vapor. If attention were restricted to planar premixed flames, then the lean-limit mole fraction of H2 would be found to be roughly ten percent, more than twice the observed flammability limits, thereby emphasizing the relevance of the flame-ball phenomena. Numerical integrations using detailed models for chemistry and radiation show that a onestep chemical-kinetic reduced mechanism based on steady-state assumptions for all chemical intermediates, together with a simple, optically thin approximation for water-vapor radiation, can be used to compute near-limit fuel-lean flame balls with excellent accuracy. The previously developed one-step reaction rate includes a crossover temperature that determines in the first approximation a chemical-kinetic lean limit below which combustion cannot occur, with critical conditions achieved when the diffusion-controlled radiation-free peak temperature, computed with account taken of hydrogen Soret diffusion, is equal to the crossover temperature. First-order corrections are found by activation-energy asymptotics in a solution that involves a near-field radiation-free zone surrounding a spherical flame sheet, together with a far-field radiation-conduction balance for the temperature profile. Different scalings are found depending on whether or not the surrounding atmosphere contains water vapor, leading to different analytic expressions for the critical conditions for flame-ball existence, which give results in very good agreement with those obtained by detailed numerical computations. The one-step chemistry employed in the present work, which involves a non-Arrhenius rate having a cutoff at the crossover temperature, applies with excellent accuracy to the description of lean premixed hydrogen-air combustion, i.e, for f(0:5 at atmospheric pressure, and could be used for instance in the numerical simulation of the propagation of curved or cellularflames in ultra-lean reactive atmospheres, of interest for safety analyses related to the storage, transport, and handling of hydrogen.