The CFD-tool FLOWer solves the compressible Reynolds-averaged Navier-Stokes equations on block structured grids. It is optimized for the simulation of exterior flows in the subsonic, transonic and supersonic flow regime. FLOWer is developed by the German Aerospace Center DLR with contributions from several German universities. The code is intensively used by the German aerospace industry.

FLOWer is based upon a finite volume discretization. Several central and upwind schemes are available. Turbulence can be modeled with algebraic, one or two equation models or Reynolds stress models. The time integration can be performed with explicit or implicit methods. The time integration of the flow equations is performed with an explicit multi-stage scheme and multi grid acceleration whereas the turbulence equations are solved with an implicit DDADI-method. For time accurate simulations an implicit dual time stepping method is available.

FLOWer can handle meshes with hanging nodes, grid overlap (Chimera) and moving/deforming meshes. For shape optimization, an inverse design option and an adjoint method is available. The flow solver is parallelized based on MPI and is optimized for vector computers.

Example of high performance computing with FLOWer

The prediction of the flow field around a helicopter is challenging for any CFD method. Various flow phenomena including boundary layers, flow separations, vortices and widely disparate velocities must be considered. The capabilities of FLOWer are demonstrated by a simulation of the unsteady flow around a BO105 helicopter wind tunnel model including the model support strut. The computational mesh was created by using the overlapping grid approach. This method accounts for the moving blades and allows simplification of the mesh generation. The total grid system consists of 11.7 million grid cells. The computation of the unsteady flow took four weeks using eight processors of the NEC SX6 vector computer. The results presented in the figures show the pressure distribution on the body surface and the vortices in the flow field.


Dr. Martin Galle
NEC High Performance Computing Europe
European HPC Technology Center,
Phone: ++49-711-78055-19

Thorsten Schwarz
German Aerospace Center,
Phone: ++49-531-295-2887