ERCIM News No.39 - October 1999

## Working Group Fluid Mechanics

by Ullrich Becker-Lemgau

The ERCIM-Working Group on Fluid Mechanics was established in 1998. So far five ERCIM institutes participate in the working group:

• CWI, Computational Fluid Dynamics Group

• FORTH, Institute of Applied and Computational Mathematics

• GMD, Institute for Algorithms and Scientific Computing

• INRIA, research team M3M - Multi-Models and Numerical Methods

• SZTAKI

Two main research areas in the context of Computational Fluid Dynamics (CDF) were chosen to build the focus of the working group:

• Multidisciplinary Applications (coupling) and

• Shallow water equations (numeric, solver, applications).

As a first action a workshop will be proposed for the ERCIM 10th Anniversary Event, held in Amsterdam.

Relevance of the Topic

Fluid mechanics has always belonged to the dominating application disciplines in high performance computing. Many fluid mechanics problems of high economic importance cannot be solved experimentally at all or only at a considerable amount of cost and time. The only suitable way of solving these problems is by computation. This has been recognized long ago by the fluid mechanics community. Correspondingly, this application field has always had a strong influence on the progress in developing numerical algorithms and new computer architectures.

Significant progress in this field has been achieved worldwide during the past years. Parallel application codes and innovative algorithmic approaches have been developed, which offer the possibility to further reduce the computing times for such computations. Due to this progress the numerical simulation of multidisciplinary problems has become possible.

Objectives of the Working Group

Extremely high demands on designing accurate prototypes for example in the fields of medical research, aircraft construction, shipbuilding and automotive industries require multidisciplinary simulations. For instance heart valves, airfoils or power plants are exposed to powerful loads in their daily use due to the interactions between fluid and structure. This class of coupled applications opens a new dimension in scientific computing and engineering.

Many complex physical phenomena can be regarded as coupled problems. These are posed as a combination of at least two problems described by systems of partial differential equations. The computation of each single system is usually performed on different, connected domains, possibly with grids of different structures. Therefore, such phenomena are mainly simulated separately using different highly specialized codes.

After dramatic progress both in parallel software and parallel hardware technology, coupled simulations are close at hand. One approach is to solve the governing equations within one code. However, a drawback of this approach is that a completely new code has to be written. The time needed to develop such a code from scratch will be very large since the years of experience in all involved disciplines are not directly reused. Therefore the possibility of running loosely coupled problems using a coupling interface is a practical solution.

Such a coupling interface is already available: the Mesh based Parallel Code Coupling Interface MpCCI, which was developed by GMD-Institute for Algorithms and Scientific Computing during the last three years. MpCCI enables a loose coupling between existing and validated parallel simulation codes based on the Message Passing Interface (MPI) standard.

One of the main objectives of this working group will be research in the area of multidisciplinary applications. Possible topics will be numerics, algorithms, interpolation or industrial applications. MpCCI can be used as a tool or framework for joint projects with the ERCIM partners.

Links:

Fluid Mechanics Working Group: http://www.gmd.de/SCAI/scicomp/ERCIM/fluid-dynamics/

Please contact:

Barbara.Steckel - GMD

Tel. +49 2241 14 2768

E-mail: barbara.steckel@gmd.de

return to the ERCIM News 39 contents page