  Computational Steering, the combination of a simulation back-end with a
visualisation front-end, offers great possibilities to exploit and optimise
scenarios in engineering applications. Due to its interactivity, it requires
fast grid generation, simulation, and visualisation and, therefore, mostly has
to rely on coarse and inaccurate simulations typically performed on rather
small interactive computing facilities and not on much more powerful
high-performance computing architectures operated in batch-mode. This paper
presents a steering environment that intends to bring these two worlds - the
interactive and the classical HPC world - together in an integrated way. The
environment consists of efficient fluid dynamics simulation codes and a
steering and visualisation framework providing a user interface, communication
methods for distributed steering, and parallel visualisation tools. The gap
between steering and HPC is bridged by a hierarchical approach that performs
fast interactive simulations for many scenario variants increasing the accuracy
via hierarchical refinements in dependence of the time the user wants to wait.
Finally, the user can trigger large simulations for selected setups on an HPC
architecture exploiting the pre-computations already done on the interactive
system.
