The effects of boundary topography on convection in Earth′s core

We present the first investigation that explores the effects of an isolated topographic ridge on thermal convection in a planetary core-like geometry and using core-like fluid properties (i.e. using a liquid metal-like low Prandtl number fluid). The model′s mean azimuthal flow resonates with the ridge and results in the excitation of a stationary topographic Rossby wave. This wave generates recirculating regions that remain fixed to the mantle reference frame. Associated with these regions is a strong longitudinally dependent heat flow along the inner core boundary; this effect may control the location of melting and solidification on the inner core boundary. Theoretical considerations and the results of our simulations suggest that the wavenumber of the resonant wave, LR, scales as Ro−1/2, where Ro is the Rossby number. This scaling indicates that small-scale flow structures [wavenumber ] in the core can be excited by a topographic feature on the core-mantle boundary. The effects of strong magnetic diffusion in the core must then be invoked to generate a stationary magnetic signature that is comparable to the scale of observed geomagnetic structures [

Generating Counterexamples of Model-based Software Product Lines: An Exploratory Study

International audienceModel-based Software Product Line (MSPL) engineering ai- ms at deriving customized models corresponding to individ- ual products of a family. MSPL approaches usually promote the joint use of a variability model, a base model expressed in a specific formalism, and a realization layer that maps variation points to model elements. The design space of an MSPL is extremely complex to manage for the engineer, since the number of variants may be exponential and the derived product models have to be conformant to numerous well-formedness and business rules. In this paper, the objec- tive is to provide a way to generate MSPLs, called counterex- amples, that can produce invalid product models despite a valid configuration in the variability model. We provide a systematic and automated process, based on the Common Variability Language (CVL), to randomly search the space of MSPLs for a specific formalism. We validate the effective- ness of this process for three formalisms at different scales (up to 247 metaclasses and 684 rules). We also explore and discuss how counterexamples could guide practitioners when customizing derivation engines, when implementing check- ing rules that prevent early incorrect CVL models, or simply when specifying an MSPL

Managing variability in multi-views engineering : A live demo

International audienceThis paper presents a tool-suite to model variability of a Software Product Line with feature models in the context of multi-views engineering. This tool-suite proposes four modules: (i) to model variability of views using a feature diagram, (ii) to select features required for a specific product, (iii) to derive a product and (iv) to visualize variability information directly inside the base-model editor. This tool is developed and tested on the ANR Movida project which deals with multi-views engineering as part of Model-Driven Engineering

Generating Counterexamples of Model-based Software Product Lines: An Exploratory Study

International audienceModel-based Software Product Line (MSPL) engineering ai- ms at deriving customized models corresponding to individ- ual products of a family. MSPL approaches usually promote the joint use of a variability model, a base model expressed in a specific formalism, and a realization layer that maps variation points to model elements. The design space of an MSPL is extremely complex to manage for the engineer, since the number of variants may be exponential and the derived product models have to be conformant to numerous well-formedness and business rules. In this paper, the objec- tive is to provide a way to generate MSPLs, called counterex- amples, that can produce invalid product models despite a valid configuration in the variability model. We provide a systematic and automated process, based on the Common Variability Language (CVL), to randomly search the space of MSPLs for a specific formalism. We validate the effective- ness of this process for three formalisms at different scales (up to 247 metaclasses and 684 rules). We also explore and discuss how counterexamples could guide practitioners when customizing derivation engines, when implementing check- ing rules that prevent early incorrect CVL models, or simply when specifying an MSPL

Effects of bottom topography on the spin-up in a cylinder

Motivated by better understanding the long-standing issue of the role of topography on the transport of angular momentum in rapidly rotating fluids, we conducted spin-up experiments in a straight cylinder with a regular pavement of rectangular blocks at the bottom. We perform particle image velocimetry measurements to monitor the decay of the initial differential motion generated by the sudden increase of the container rotation rate. We observe that the re-synchronization time, the so-called spin-up time, is shorter in the presence of topography with a minimum at a particular length scale of the topography pattern. We show evidence of energy transport by inertial waves as well as non-linear mechanisms leading to a scaling of the spin-up time significantly different from the classical E−1/2 in the absence of topography.ISSN:1070-6631ISSN:1089-7666ISSN:0031-917

Latitudinal libration driven flows in triaxial ellipsoids

ISSN:0022-1120ISSN:1469-764

Corrigendum: Latitudinal libration driven flows in triaxial ellipsoids [J. fluid mech. 771, 193-228 (2015)]

ISSN:0022-1120ISSN:1469-764

Le nouveau défi de la coordination des langages de modélisation. Gestion de l'hétérogénéité des modèles dans le développement et l'exécution de systèmes logiciels complexes

National audienceL'ingénierie dirigée par les modèles (IDM) vise à réduire la complexité accidentelle des développements de systèmes logiciels complexes. L'IDM vise à résoudre ce problème par l'utilisation de techniques de modélisation qui prennent en charge la séparation des préoccupations et la génération automatique des artefacts du système à partir de modèles (e.g., cas de tests, code d'implantation, scripts de déploiement et de configuration). Un modèle décrit un aspect du système et est généralement créé ou dérivé pour un objectif particulier. Les modèles des différents aspects du système sont toutefois rarement manipulés indépendamment les uns des autres. Les ingénieurs systèmes sont donc confrontés à la tâche difficile de relier et synchroniser des informations issues de différents modèles. Les environnements modernes de conception et d'implantation de langages de modélisation offrent un bon support pour le développement d'un langage de modélisation, mais offrent peu ou pas de support pour permettre une utilisation coordonnée de plusieurs langages de modélisation. Supporter l'utilisation conjointe de plusieurs langages de modélisation pour la définition d'un système correspond au défi que nous qualifions de coordination des langages de modélisation, c'est-à-dire l'utilisation de plusieurs langages de modélisation pour soutenir le développement coordonné des aspects hétérogènes d'un système. Dans cet article, nous faisons tout d'abord un bilan sur l'adoption de l'IDM et le constat de la multiplication des langages de modélisation dans les processus de développement industriels. Nous exposons ensuite le nouveau défi que constitue la coordination des langages de modélisation, et présentons les pistes de solutions actuellement explorées par les partenaires de l'initiative GEMOC

Ecoulements induits par les librations forcées dans les couches liquides des planètes

Orbital dynamics that lead to forced longitudinal libration of celestial bodies also result in an elliptically deformed equatorial core-mantle boundary. In the present study, we investigate the effect of the topographic coupling on the flow in the liquid layers of a librating planet through a coupled numerical-experimental approach. We report the first evidence of libration-driven elliptical instability in a non-axisymmetric container. It is shown that intermittent turbulence, characteristic of such instabilities, is associated with an enhanced zonal flow