Simulation of Complex Turbulent Flows -- Drag Reduction for Internal Flows by Dimpled Surfaces --

Computational Fluid Dynamics

Universität Erlangen-Nürnberg
Lehrstuhl für Strömungsmechanik

Simulation of Complex Turbulent Flows-- Drag Reduction for Internal Flows by Dimpled Surfaces --M. Breuer, LSTM ErlangenDrag reduction for wall-bounded turbulent flows is of majorimportance for many technical applications because it leads to enormous savings in energy consumption. For example, millions of liters of kerosene could be saved if the drag of commercial aircrafts is reduced by only 1%. But also for internal flows the significance of drag reduction techniques is huge. Besides riblets for external flowsand polymers for internal flows (e.g. in pipelines) a new idea called dimple technique was recently introduced. Dimples are macroscopic surface structures which were designed to reduce the drag of wall-bounded flows. First experimental tests with dimples were successful leading to drag reductions of up to 20 %. However, until today the mode of action of dimpled surfaces is not understood atall. Detailed simulations with modern computational techniques such as DNS and LES are planned to bring light into the secret of dimples and their physical mechanism of drag reduction. For that purpose, the highly optimized Navier-Stokes solver LESOCC is applied and DNS aswell as LES predictions of wall-bounded flows with dimpled surfaces will be carried out and analyzed in detail. Complementary experimental studies at LSTM Erlangen complete the entire investigation.