Abstract

Turbulent flows behind bluff bodies are ubiquitous in engineering applications, with road vehicles being an example of significant environmental and economic relevance. Therefore a mathematically tractable description of them is desirable for their prediction and control. This talk will give insight into the global dynamics and symmetries of turbulent three-dimensional wakes generated by axisymmetric bluff-bodies and their low-order description at high Reynolds numbers. Analysis is based on experimental results from a wind-tunnel mounted axisymmetric bluff body at a diameter-based Reynolds number of ~200,000 – well into the turbulent regime. The modelling is also extended in the presence of external forcing, provided by a Zero-Net-Mass-Flux actuator (synthetic jet) located on the rear base of the bluff body. Finally, we will show how these models can be obtained directly from the governing Navier-Stokes equations through a weakly nonlinear analysis, providing a general framework for the description of systems with broken symmetries and turbulent dynamics.