POPINDA - Portable Parallelization of Industrial Aerodynamic Applications
by Anton Schüller
The use of computer simulations in the specification and design of
modern aircraft have a decisive impact on the competition in the aerospace
industrial market. Increasing demands for cost efficiency, speed, safety,
comfort, noise reduction and environmental protection necessitate simulations
with increasing complexity in the aerospace industry. Optimized codes running
on high performance computers, ie parallel computers, must be used to meet
those requirements.
In the cooperation project POPINDA (Portable Parallelization of Industrial
Aerodynamic Applications), the innovative step into parallel computing
has been completed: over a period of more than three years, the partners
Daimler-Benz Aerospace Airbus GmbH, Bremen, Daimler-Benz Aerospace AG,
Munich, Deutsche Forschungsanstalt für Luft- und Raumfahrt, Braunschweig,
and GMD Sankt Augustin were involved in the collaborative development of
the parallel programs FLOWer and NSFLEX-P for the computation of flow fields
around aircraft. Additional partners were IBM Heidelberg and ORCOM GmbH,
Freiburg. Both programs in POPINDA achieved a high standard in the area
of Computational Fluid Dynamics (CFD) worldwide.
The parallelization strategy of FLOWer and NSFLEX-P, solving the Reynolds
averaged Navier-Stokes equations, is based on grid partitioning and the
message passing programming model. For message passing, both programs use
the portable high level communications library CLIC (Communications Library
for Industrial Codes), also developed in POPINDA. CLIC performs and optimizes
all data exchange between the allocated processors, guaranteeing a high
degree of efficiency and flexibility. Since the CLIC library supports the
portable communication interfaces PARMACS and MPI (and since the CLIC library
was also developed for sequential platforms), both programs can be run
on any parallel and sequential platform.
During POPINDA, the parallelized production codes were tested in industry.
They proved to be independent of the hardware and significantly faster
than the old industrial production codes. Moreover, a careful validation
showed the high quality of the results leading to an increased confidence
in computational flow calculations. POPINDA made an important contribution
towards an improved efficiency and competitiveness of the German aerospace
industry.
Using the POPINDA parallel programs, it is currently possible to calculate
the flow field over a wing-body-configuration with extremely high resolution
on a grid consisting of over 6.5 million grid points. Such a calculation
corresponds to the solution of a non-linear system of equations with more
than 33 million unknowns. Remarkably, the results are available in less
than three hours.
On top of that, new algorithms were developed for further reduction
of the computation time of a flow calculation. Especially the adaptive
methods must be mentioned here, in which the number of grid points and
thus the size of the system of equations to solve is fitted to the concrete
problem in an intelligent way. The accuracy of numerical calculated flow
data principally increases with increased grid resolution, ie with an increased
number of grid points. However, the grid resolution of the total grid must
not be necessarily constant. In large, but a priori unknown parts of the
flow field a lower grid resolution is sufficient to reach a prescribed
accuracy than in others.
Both POPINDA codes FLOWer and NSFLEX-P lay the foundation for current
as well as future research and development projects in the area of numerical
flow simulation. FLOWer, for example, is one of the foci of the MEGAFLOW
national CFD project, aiming at the goal of achieving the simulation of
a complete aircraft at cruise and take off/landing conditions with a reliable,
efficient and quality controlled program system.
With the POPINDA programs, the way towards future challenging CFD problems
has been prepared. Among other algorithmic developments, some issues are
highlighted here:
- the development of flexible grid and data structures - the numerical
simulation of unsteady flows around aircraft - the optimization of aircraft
components with respect to interference effects and
- the coupled solution of structure mechanical and aerodynamic problems,
a very important issue in the process of wing design.
More information on Popinda at http://www.gmd.de/SCAI/num/popinda/popinda.html
Please contact:
Anton Schüller - GMD
Tel: + 49 2241 14 2572
E-mail: anton.schueller@gmd.de
