Any simulation consists of four main steps:

Creation of a 3D CAD-model of the geometry which comes into contact with the fluid

• Based on this CAD-model the computational domain is discretized by a computational mesh. Depending on the software code employed and the application, the mesh is build up from hexahedra, tetrahedra or polyhedron elements, or of a combination of such elements. Special care is needed near the walls in order to correctly resolve the boundary layer. A good quality computational mesh is a prerequisite for reliable simulation results.
• Before running the simulation the boundary conditions as well as the fluid properties have to be defined. Turbulence is taken into account by a turbulence model, while for multiphase flows the behavior and interaction of the various phases has to be determined by appropriate physical models. For turbomachinery applications the transfer of the fluid information from the rotating to the stationary frame of reference has to be specified by selecting an interface model.
  Since CFD setups of complex geometries or complete machines may require computational meshes consisting of several millions of elements, and quite often the nature of the flow is transient, the solver has to be run in parallel on several processors.
• Once the simulation is converged, the vast amount of data generated has to be processed and analyzed. Depending on the project the information extracted may consist of 2D and 3D views of the flow field, transient animations (i.e. movies), calculation of characteristic numbers (e.g. efficiency, losses, heat transfer, power etc.) and analysis of critical flow phenomena, like vortex structures.
  Such a postprocessing can be automated and reused if a design has to be evaluated at different operating conditions or geometry has to be optimized.

Hardware

The Advanced Fluid Technology group runs its own high performance computing (HPC) Linux cluster. Computing power consists of 116 processors, 238 cores, respectively and 500GB of RAM. For the problem setup and postprocessing, each CFD engineer uses a two-processor graphic workstation.

A queuing system manages the workload of the HPC cluster and assures optimum use of the computation resources. A dedicated backup and archive system fulfills the needs of the quality assurance requirements.