Model reduction for transport phenomena
- © PK
Model reduction tries to describe large and numerical complex systems by much smaller ones, to save simulation time in design or control processes. Unfortunately, model reduction fails for transport dominated systems, like propagating flames, moving shocks or traveling acoustic waves. The goal of our research is to structurally extend the available standard methods for these kind of systems.
Acoustics / Liner
- © LS
One main research subject of the Institute of Fluid Mechanics and Engineering Acoustics deals with Helmholtz Resonators in a Turbulent Boundary Layer.
For industrial use, hollow chambers in a turbulent flow are
frequently surveyed. Often in expansive experimental runs, various
configurations are tested in order to fulfill design objectives.
Large-scale sound reinforcement for speech and
music is nowadays typically realised with line array systems. Their
drive has to be optimised with respect to several degrees of freedom,
e.g.arrangement, geometry, construction of the boxes and different
boundary constraints, e.g. geometry of the auditory, areas that have
to be avoided, available acoustic power. It is an ill-posed inverse
- © CW/ML
The analysis of complex fluid mechanical phenomena
is based on experimental and numerical analysis. Both approaches
provide suitable data, but no complete and exactly matching picture of
a flow, which is to be examined. Experimental data are usually
incomplete, because not every state variable is accessible by
measurements and numerical solutions are often affected by ...
Fluid-structure interaction (insect flight)
- © TE
team combines the unique perspectives of high-performance computing
and experimental biology to address the challenging question of how
flying insects cope with turbulent perturbations in the surrounding
air flow. This pluridisciplinary project assembles physics, numerical
modeling and simulation with experimental biology.
- © SBL
The aim of the project is the depth investigation
of the processes of pulsating-detonative combustion. Essential for the
technical application of pulsating combustion is a fast and reliable
transition from deflagration to more efficient detonation (DDT). In
the experiment, a reliable DDT was found for a special geometry,
consisting of a chamber with a convergent-divergent nozzle. The
numerical simulation finds the DDT at the narrowest cross section as a
complex interaction of different phenomena, in particular flame
acceleration and shock focusing, which in turn is consistent with the
measured pressure data. The underlying phenomena are strongly
dependent on the speed of sound, heat release and characteristics of
the flame as well as the boundary and start conditions, thus on the
mixture properties and the operating conditions.
High speed flows with ion transport
- © PKrah
Gas flows transporting charged particles occur in
different fields. Our focus are vacuum devices, where molecules are
ionized to manipulate and analyze these. An important application is
the mass spectrometry, which, in all its variations and extensions, is
one of the work horses in chemical and biochemical research.
In such devices, particles, like complex biochemical molecules, are typically ionized under atmospheric conditions and transferred to low pressure conditions, whereby the gas is removed and intact ions of theses molecules in vacuum are obtained. This is the prerequisite for many accurate and detailed investigation methods. Ionization under atmospheric conditions, as in electrosprays, allows ionization of molecules which would be destroyed by other, more direct methods.
The vacuum transfer inevitably yields high speed flows over high pressure range, i.e. high speed sonic and supersonic flows. These take place in complex geometries dictated by the need to create special, appropriate electric fields to guide the ions, i.e. ion optics.