This paper presents an experimental study of the effect of trailing edge serrations on airfoil instability noise. Detailed aeroacoustic measurements are presented of the noise radiated by an NACA-0012 airfoil with trailing edge serrations in a low to moderate speed flow under acoustical free field conditions. The existence of a separated boundary layer near the trailing edge of the airfoil at a...

We use direct numerical simulations to study control of jets in crossflow by axial pulsing. Our main idea is that pulsing generates vortex rings; the effect of pulsing on jets in crossflow can therefore be explained by studying the behavior of vortex rings in crossflow. A method is proposed that allows optimal values of pulsation frequency, modulation and energy to be estimated a priori. This i...

When load is applied to fcc nanograins, leading partial dislocations nucleate at grain boundary steps and propagate into the grain, leaving stacking faults behind. The extent to which these faults expand before a trailing partial is emitted generally does not equal the equilibrium separation distance of the corresponding full dislocation. Here we use a density functional theory – phase field di...

Miniflaps at the trailing edges of airfoils (e.g., Gurney flaps or divergent trailing edges) change the Kutta condition and thus produce higher lift. Unfortunately, however, the drag is also increased due to the flow separation downstream of this particular type of trailing edge. Therefore, the trade-off between beneficial and detrimental effects is considered in this paper. Various aspects of ...

A central service of a constraint programming system is search. In almost all constraint programming systems search is based on trailing, which is well understood and known to be efficient. This paper compares trailing to copying. Copying offers more expressiveness as required by parallel and concurrent systems. However, little is known how trailing compares to copying as it comes to implementa...

This paper presents results of an empirical study on the flow and noise generated by the trailing edge of a flat plate encountering low turbulence fluid flow. Simultaneous measurements of flow and far-field noise data have been taken in an anechoic wind tunnel at the University of Adelaide. Velocity data about the trailing edge and in the wake have been measured using hot-wire anemometry. These...

Direct numerical simulation is used to study the mixing of a passive scalar by a vortex ring issuing from a nozzle into stationary fluid. The ‘formation number’ (Gharib et al. J. Fluid Mech. vol. 360, 1998, p. 121), is found to be 3.6. Simulations are performed for a range of stroke ratios (ratio of stroke length to nozzle exit diameter) encompassing the formation number, and the effect of stro...