A Steering Environment for Online Parallel Visualization of Legacy Parallel Simulations

International audienceIn the context of scientific computing, the computational steering consists in the coupling of numerical simulations with 3D visualization systems through the network. This allows scientists to monitor online the intermediate results of their computations in a more interactive way than the batch mode, and allows them to modify the simulation parameters on-the-fly. While most of existing computational steering environments support parallel simulations, they are often limited to sequential visualization systems. This may lead to an important bottleneck and increased rendering time. To achieve the required performance for online visualization, we have designed the EPSN framework, a computational steering environment that enables to interconnect legacy parallel simulations with parallel visualization systems. For this, we have introduced a redistribution algorithm for unstructured data, that is well adapted to the context of M × N computational steering. Then, we focus on the design of our parallel viewer and present some experimental results obtained with a particle-based simulation in astrophysics

An optimized finite-element library: Akantu

Akantu means a little element in Kinyarwanda, a Bantu language. From now on it is also an opensource object-oriented library which has the ambition to be generic and efficient

Specification of a micro-transgranular fracture parameter

The micro-transgranular fracture calibration with a help of an efficient parallel numerical tool is demonstrated in this poster

Conception et mise en oeuvre d'une plate-forme de pilotage de simltions numériques parallèles et distribuées

Le domaine de la simulation numérique évolue vers des simulations de phénomènes physiques toujours plus complexes. Cela se traduit typiquement par le couplage de plusieurs codes de simulation, où chaque code va gérer une physique (simulations multi-physiques) ou une échelle particulière (simulations multi-échelles). Dans ce cadre, l'analyse des résultats des simulations est un point clé, que ce soit en phase de développement pour valider les codes ou détecter des erreurs, ou en phase de production pour confronter les résultats à la réalité expérimentale. Dans tous les cas, le pilotage de simulations peut aider durant ce processus d'analyse des résultats. L'objectif de cette thèse est de concevoir et de réaliser une plate-forme logicielle permettant de piloter de telles simulations. Plus précisément, il s'agit à partir d'un client de pilotage distant d'accéder ou de modifier les données de la simulation de manière cohérente, afin par exemple de visualiser "en-ligne" les résultats intermédiaires. Pour ce faire, nous avons proposé un modèle de pilotage permettant de représenter des simulations couplées et d'interagir avec elles efficacement et de manière cohérente. Ces travaux ont été validés sur une simulation multi-échelles en physique des matériaux.The numerical simulations evolve more and more to simulations of complex physical phenomena through multi-scale or multi-physics codes. For these kind of simulations data analysis is a main issue for many reasons, as detecting bugs during the development phase or to understand the dynamic of the physical phenomena simulated during the production phase. The computational steering is a technique well suited to do all this kind of data analysis. The goal of this thesis is to design and develop a computational steering framework that take into account the complexity of coupled simulations. So, through a computational steering client we want to interact coherently with data generated in coupled simulations. This afford for example to visualize on-line the intermediate results of simulations. In order to make this possible we will introduce an abstract model that enables to represent coupled simulations and to know when we can interact coherently with them. These works have been validated on a legacy multi-scale simulation of material physics

Implementation of a parallel finite-element library: test case on a non-local continuum damage model

This paper presents an efficient method to implement a damage law within an explicit time-integration scheme, in an open-source object-oriented finite-element framework. The hybrid object/vector design of the framework and implementation choices are detailed in the special case of non-local continuum damage constitutive laws. The computationally demanding aspect of such constitutive laws requires efficient algorithms, capable of using High Performance Computing (HPC) clusters. The performance of our approach is demonstrated on a numerically and physically challenging 3D dynamic brittle-fragmentation test case. An almost perfect scalability is achieved on parallel computations. The global dynamics and energy terms are in good agreement with classical cohesive models’ predictions

Toward a Computational Steering Environment for Legacy Coupled Simulations

In this paper, we present an abstract model to steer legacy coupled simulations that follow the Multiple-SPMD paradigm or the client/server paradigm. This model extends our previous work for the steering of classical SPMD simulations. It describes the application in terms of execution flow, complex distributed data objects and user interactions. Thanks to this abstraction, we define a coordination algorithm that allows us to efficiently interact with the simulation and to overcome the time-coherence problem raised by coupled simulations. 1