The working group introduces itself

The main focus of the chair is the investigation of turbulent flows. For this purpose, canonical flows (e.g. free jet, mixing layers, channel and pipe flows, isotropic and homogeneous turbulence) as well as realistic configurations from industry were investigated.

We are particularly interested in compressibility effects in sub- and supersonic flows, altered energy transfer and heat transfer. In this context, intrinsic compressibility effects (fluctuations in dilatation due to pressure fluctuations) or so-called "variable property effects" (the effects of large differences in density or temperature or due to different species in mixing processes) are specifically investigated.

At the same time, we are trying to find out how turbulent and laminar flows can be specifically influenced. For this purpose, the adjoint Navier-Stokes equations were solved to minimize cost functions, e.g. to reduce noise or friction drag. Other possibilities were also used, including the targeted generation of wall oscillations to reduce the resistance of wall-bound flows.

The chair has decades of experience in performing direct numerical simulations (DNS), large eddy simulation (LES) or statistical modeling (RANS). Many pioneering DNS have been performed or, for example, filter-based LES models have been developed, as well as automated methods for physically based grid generation for RANS models motivated by dissipation elements.

In recent years, much expertise has been built up in the field of Lattice-Boltzmann Simulation (LBM). New methods (Semi-Lagrangian LBM (SLLBM) have been developed for incompressible and compressible flows, which can avoid the coupling of time and space steps(NATRIUM). In addition, an LBM solver based on PyTorch was written(LETTUCE), which enables, for example, automatic differentiation or the use of machine learning methods. As a result, LBM methods with neural collision operators or optimized non-reflective boundary conditions were developed.

The chair has recently acquired an aeroacoustic wind tunnel

of Göttingen design with an open measuring section (details here). The chair uses this to conduct research in the field of aeroacoustics of turbulent flows, flanked by numerical simulations.