Projects | Christophe Picard

HAMM

Thu, 16 Jul 2026 07:14:32 +0200

This research project aims at the development, analysis and software implementation of mathematical models for multiscale applications on hybrid architectures. Large scale multiscale applications are indeed within reach with the emerging computing infrastructures, but they require accurate and robust multiscale numerical methods that take into account these new architectures. This is very challenging as current software were not designed for these methods and architectures. As a matter of fact, scientists and engineers need to manage (i) the complexity of the underlying multiscale models, usually expressed in terms of a partial differential equation (PDE) system completed with algebraic closure laws, (ii) the complexity of numerical methods used to solve the PDE systems, and finally (iii) the complexity of the low level computer science services required to have efficient software on modern hybrid hardware (e.g. multicore CPU/GPU). Robust and effective multiscale methods as well as advanced programming techniques need to be combined to fully benefit from massively hybrid parallel architectures.

Even though this project revolves around applied mathematics and multiscale numerical methods, it is truly multidisciplinary and critically requires the expertise of specialists of the applications, computer scientists and computer designers. That’s why we create a strong consortium : (i) CEA and IFP leading the large scale multiscale application specifications, (ii) UJF leading the multiscale numerical methods development and efficient implementation on hybrid architectures and finally (iii) BULL leading the benchmarking activities and ultimately the sizing of future super computing infrastructure according to nowadays constraints such as energy costs savings.

I-Worms

Thu, 16 Jul 2026 07:14:32 +0200

One of the most difficult tasks of operating a seismic net- work is the verification of data quality. In particular, the accuracy the relative travel time measurements between seismic stations are crucial for tomographic experiments and event localization. With the recent development of larger and denser temporary networks in geophysics and seismology, array processing techniques imply the use of frequency-dependent phase matching algorithms for which a perfect array synchronization is also mandatory. Clock synchronization among the instruments constituting an array is, however, difficult without a direct communication between them. On land, data logger clocks can be ensured by frequent synchronization with GPS satellites acting as a highly accurate, external reference clock and time errors result mainly from changes to the electronic equip- ment at particular stations. Recent works also suggest that apparent clock jumps are caused by missing samples that correspond to cases when the data logger fail to write a short chunk of samples to disk. Marine seismology also relies on temporary deployments of stand- alone seismic ocean bottom seismometers (OBS). For typical OBS deployments, the problem is even worse because the clocks are only synchronized to GPS time before and after deployments, which can last up to several years. In between, the recorder clocks may drift and float at unknown rates. If the clock drifts are large or not linear and cannot be corrected for, array seismological methods cannot be applicable.

LUG2

Thu, 16 Jul 2026 07:14:32 +0200

The FUI project LUG2, labeled by Minalogic, proposes to develop a new generation of acoustic arrays to accurately identify, localize and quantify noise sources in a complex environment, using user-friendly, optimized and low-cost systems. These systems can be used in many industrial applications including transportation, mechanics, defense and energy. To achieve this objective, the project brings together three SMEs and three laboratories within the Auvergne Rhône Alpes Region.

Following the kick-off of the project in February 2017, the first results of LUG2 began to come thanks to the work carried out jointly by the Vibrations and Acoustics Laboratory of INSA Lyon and MicrodB.

Using a statistical approach and using a Markov-Monte-Carlo Chain (MCMC) method, it is now possible to obtain a confidence interval associated with each acoustic source power estimate.

Simvort

Thu, 16 Jul 2026 07:14:32 +0200

Naturally occurring flows, such as human upper airways, are highly influenced by complex geometries with varying wall properties. Consequently, mathematical or physical studies require severe simplifications of the real life geometry in order to capture the underlying principles as well as to perform in-depth repeatable studies with a limited number of parameters. Despite the simplicity of the geometry, vortex generation due to shear layer roll up occurs both for confined jet flow, such as immediately downstream from the obstacle, and for free jet flow, such as downstream from the exit. From reported studies several scientific objectives can be formulated:

In the current proposal an in depth characterisation and modelling of airflow is aimed for the onset of flow instabilities, vortex roll up and coherent structures of:

free jet
jet-obstacle interaction

as function of Reynolds number, emitting geometry, flow disturbance and boundary conditions with particular attention to the transition regime.