Aerodynamic Flows

Aerodynamics, a part of fluid dynamics, describes the laws of the flow of air or other gases, furthermore the emerging or varying forces on solid surfaces due to the effect of the gas flow. Everything that moves in the atmosphere gets in interaction with air. That is like driving a car, aerodynamics plays an important role in our daily life beginning with the simplest things up to the complicated technological devices. Maybe the most important impact of this science is in the planning of flying objects – eg.: airplanes, rockets – and the determination of the emerging forces and moments on these structures. These effects are also important at non flying objects which are moving on the ground especially at higher speed. This is why aerodynamics play also an important role in car industry with the goal to achieve a profitable air resistance (or drag coefficient) combined with lower fuel consumption. Due to extreme weather conditions, strong winds, aerodynamics has to be seriously taken into account in architecture, at planning of high buildings or bridges. In smaller scales the understanding of the air or gas flow becomes also important in pipings or ventilation systems, distributors, heat exchangers, etc…

Using Computational Fluid Dynamics (CFD) the fluid can be investigated in small details in time and space and the weak spots of the system (if any) can be detected. However the numerical efforts to calculate a complex flow can easily rise to a critical level. For these reasons various models are available to deal with such demands. Especially at high velocities and/or where turbulent effects occur, the numerical effort can be reduced by applying turbulence models. It is very important to find a reasonable compromise between the numerical effort and the level of turbulent modeling. Well known turbulence models are the k – ε or the k – ω models. In case of the LES turbulence models the large eddies in the fluid will be resolved to get a more detailed result. If even the small eddies on Kolmogorov scale would be resolved during the calculation, the simulation is called Direct Numerical Simulation (DNS), where even the finest effects of the fluid flow can be recognized. The drawback of the DNS is the very high computational effort.

Our research group is trained in the field of aerodynamics and experienced at choosing or/and implementing the suitable numerical solver for a specific flow investigation.