Michael Kornhaas

Influence of Time Step Size and Convergence Criteria on Large Eddy Simulations with Implicit Time Discretization

Subject of this work is the influence of numerical parameters on quality and efficiency of Large Eddy Simulations. Variations of the time step size and the convergence criterion are considered. The influence of these parameters on mean values and computational time are presented and discussed. The computations were carried out for the well known test case “Periodic flow over a 2D hill”.

High-Performance Computing Techniques for Coupled Fluid, Structure and Acoustics Simulations

A framework for fully coupled numerical simulation of fluid flow, structural deformation, and acoustics is presented. The methodology involves an implicit partitioned approach for fluid-structure interaction, a viscous-acoustic splitting technique for flow acoustics, and corresponding coupling schemes. All components are designed for the use on parallel high-performance computers. Special emphasis is given to the use of geometric multi-grid techniques in order to increase the efficiency of the numerical simulations. Results for several test cases illustrate the capabilities of the approaches considered.

Investigation of the Flow around a Cylinder Plate Configuration with Respect to Aerodynamic Noise Generation Mechanisms

In this work we present a Large Eddy Simulation of an aero-acoustic test case consisting of a plate located in the turbulent wake of a circular cylinder. This configuration is very attractive for the validation of low Mach number aero-acoustic codes and coupling techniques, since a high sound pressure level is present at a very low Mach number and also because its simple geometry. Further it seems to be an interesting test case for future works if besides aero-acoustics also fluid induced vibrations are of interest.

High-Order Methods for Large-Eddy Simulation in Complex Geometries

Developing high-order methods for large-eddy simulation (LES) is of interest to avoid mixing between subgrid scale modeling contributions and approximation errors of the numerical method. Two different approaches are investigated. The first one focuses on the so-called Spectral Vanishing Viscosity LES (SVV-LES) approach, which allows to extend the well known capabilities of spectral methods from laminar to turbulent flows, while the second one rather investigates the possibility of extending a second order finite volume code to higher order approximations. For the SVV-LES approach, a volume penalization like technique is used to address complex geometries.