New Collaborative Working Environments for Multiphysics Coupled Problems

International audienceBecause large scale multiphysics problems are expected to be orders of magnitude larger than current single discipline applications, like weather forcasting, environmental disaster prevention and emergency management, new computing technologies are required. Among these technologies are wide area grids and distributed computing, using cluster and grid-based environments. It is clear that large supercomputers, PC-clusters and wide area grids are currently used for demanding e-science applications, e.g., nuclear and environmental simulation. It is not so clear however what approaches are currently the best for developing multiphysics applications. We advocate in this paper the use of combined Web and grid-based techniques that are combined for a seamless uptake by the users, i.e., the applications designers, and users running multidisciplinary codes and business software, e.g., decision support tools. This paves the way for New Collaborative Working Environments

Distributed Workflows for Multi-physics Applications in Aeronautics

International audienceThe industry requires innovative technologies to support the numeric design and simulation of manufactured products in order to reduce time to market delays and improve the performance of the products and the efficiency of the industries in the global competitive market. Innovation also requires advanced tools to support the design of new products. For example, remote teams are working collaboratively on the preliminary design of future aircraft that will be “safer, quieter, cleaner”, and environmentally friendly by 2020. The automotive industry has similar concerns. The telecom industries (e.g., mobile phones design) and nuclear power plant design face large-scale multi-physics simulation and optimization challenges. This paper suggests that distributed workflows running on computational grids are adequate to support their application needs

Distributed Optimization using Virtual and Real Game Strategies for Aerodynamic Design

This report approaches the question of multi-disciplinary optimization for optimum shape design in Aerodynamics using game theory. The employed optimizer is based on control theory, which produces very robust optimization algorithms particularly well suited for problems of constrained optimizations. We perform an airfoil drag reduction under the constraint of constant , and a lift maximization under the constraint of constant C_d . Here, we introduce a scalar adjoint variable to satisfy these constraint- s. Comparing with the unconstrained case, these constraints can be easily implemented by introducing an additional scalar algebraic adjoint equation. Furthermore, the above methodological ingredients are combined with a formulation derived from Game Theory to treat multi-point airfoil optimization- . Airfoil shapes are optimized according to various aerodynamic criteria (under conflict). Each `player' in a symmetric Nash game optimizes one's own criterion using information provided by the others. The Nash equilibrium then corresponds to the solution of a multi-point optimization. Subsonic/Trans- onic flows around lifting airfoils are analyzed by Eulerian computations. Several kinds of airfoil splittings and aerodynamic design cases are considered illustrating virtual and real game strategies. Successful design results confirm the validity and efficency of the present design method in a parallel computing environment

Controllability Methods for the Calculation of Time-Periodic Solutions. Application to Scattering.

Projet M3NWe discuss in this article the application of controllability techniques to the calculation of the time-periodic solutions of evolution equations. The basic principles of the computational methods are presented in a fairly general context where we discuss the time discretization aspect. We apply then this general methodology to the solution of scattering problems for harmonic planar waves by two and three dimensional purely reflecting non-convex obstacles. Numerical results obtained by the above method and comparisons with the results obtained by more classical methods show the superiority of the former ones. In annexe A, we give some details on the Radar Cross Section computation

3D Harmonic Maxwell Solutions on Vector and Parallel Computers using Controllability and Finite Element Methods

Projet M3NWe consider the scattering problem for 3-D electromagnetic harmonic waves. The time-domain Maxwell's equations are solved and Exact Controllability methods improve the convergence of the solutions to the time-periodic ones for nonconvex obstacles. A least-squares formulation solved by a preconditioned conjugate gradient is introduced. The discretization is achieved in time by a centered finite difference scheme and in space by Lagrange finite elements. Numerical results for 3-D nonconvex scatterers illustrate the efficiency of the method on vector and parallel computers

Acceleration de la convergence dans le calcul des ecoulements de fluides visqueux

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Current progress on the numerical simulation of detached flows around airplanes

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