IDEMAS: Industrial demonstration of accurate and efficient multidimensional upwind and multigrid algorithms for aerodynamic simulation on unstructured grids

• Forschungsstelle: EU FRP
• Projektnummer: 97.0427
• Projekttitel Englisch: IDEMAS: Industrial demonstration of accurate and efficient multidimensional upwind and multigrid algorithms for aerodynamic simulation on unstructured grids

Schlüsselwörter (Englisch)

Accurate multidimensional upwind; multigrid; adaptive meshing;
aerodynamic simulation; unstructured grids

Alternative Projektnummern (Englisch)

EU project number: BE 97-4162

Forschungsprogramme (Englisch)

EU-programme: 4. Frame Research Programme - 2.1 Industrial and materials technologies

Kurzbeschreibung (Englisch)

See abstract

Partner und Internationale Organisationen (Englisch)

EPFL-DGM / DMA; Von Karmen Institut (B); INRIA (F), Dassault
Aviation (F), Daimler-Benz Aerospace (DASA) (D); Alenia
Aerospazio (I)

Abstract (Englisch)

The contribution of the Mechanics Department DGM of EPFL within the BRITE-EURAM IDEMAS project consists of the
research and development of parallel mesh adaptation modules and their integration within the common solver designated by
the project co-ordinator: the THOR solver. In the present phase, tetrahedra grids are considered and the flow modelling is
restricted to the inviscid case (Euler equations) as the Navier-Stokes option under the responsibility of the co-ordinator is
not yet functional.

The starting point of the present work was former research undertaken within the institute. However, most of the original
concepts required considerable modifications and improvements to extend their application to three-dimensional meshes,
with also the constraints induced by the decision of the BRITE-EURAM consortium to use overlapping partitioning and the
portable standard MPI paradigm for parallelisation. This induced considerable work on the modification of the algorithms,
with the development of new concepts and a large effort on the robustness of these methods. Particular care was taken on
grid optimisation allowing to build an adaptive module which can be applied to any industrial problem, even if the original
grid quality is poor. Whereas grid adaptation can provide highly accurate solution meshes, the goal is not only to solve
accurately the Fluid equations, but also to maintain this accuracy on as coarse and as regular mesh as possible. Such mesh
optimisation techniques use structural changes of the mesh as well as deformation and node displacement algorithms. The
original method of mesh adaptation with local refinement and derefinement lead to modifications of the of the cell edge
definitions with node deletion/adjunction which corresponds to edge splitting. Optimisation criteria were also defined in the
segment topology. In order to maintain the strong features of this method in the present work, the differences of data structure
between the underlining algorithms needed to be translated into the common code of the IDeMAS project: THOR. The
THOR data structure does not provide initially a description of the edges. Several structural changes to the data structure of
THOR have hence been introduced for our mesh adaptation capacities. The methods developed here are all local so that their
influence is limite within a so-called shell which is a sub-mesh isolated around the node or segment in consideration. These
concepts are reported in the Technical Reports annexed

The parallelisation of the adaptive modules using MPI paradigm requires the internal use of a parallel partitioner package,
PARMETIS The communication library adopted originally by the VKI within the THOR package was based on the linear
solver package Aztec. In order to maintain the adaptive mesh modules as independent and as modular as possible, all
communication is transcribed using standard MPI functionals instead. This work is still underway at present.

Datenbankreferenzen (Englisch)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 97.0427