In 1911 Theodore von Kármán first noticed the unusual alternating stream of vortices that result from fluid flowing past a cylinder. This phenomenon, now known as a von Kármán vortex street, only occurs for fluids with particular characteristics. The most important attribute, is the Reynolds number, which is the ratio of inertial forces to viscous forces in the fluid. It turns out that vortices...

Spatially periodic rows of point vortices in a 2-dimensional ideal fluid have long attracted the attention of fluid dynamicists, one of the earliest and the most popular instances being Kármán’s vortex street [6], [15, photos 94–98]. The general problem is as follows: analyse the motion of an infinite configuration consisting of vortices z1, . . . , zN ∈ C with vorticities Γ1, . . . ,ΓN ∈ R tog...

Three-dimensional flows over impulsively translated low-aspect-ratio flat plates are investigated for Reynolds numbers of 300 and 500, with a focus on the unsteady vortex dynamics at post-stall angles of attack. Numerical simulations, validated by an oil tow-tank experiment, are performed to study the influence of aspect ratio, angle of attack and planform geometry on the wake vortices and the ...

In this study, the aerodynamic sound generated from the inclined circular cylinder was investigated experimentally and numerically. The generated sound and a coherent length of velocity fluctuation along the cylinder axis were measured by a low-noise wind tunnel with endplates. The sound and the flow in wake were also simulated by Large Eddy Simulation and Lighthill-Curle’s equation. We got the...

The influence of the finiteness of the source domain on the application of Curle’s analogy for the computation of flow-generated sound is investigated in the present work. Two aspects are studied: the spurious source of sound induced by CFD boundary conditions in incompressible simulations and the error due to the truncation of the integration source domain. Two validation cases are investigate...

Animal fliers frequently move through a variety of perturbed flows during their daily aerial routines. However, the extent to which these perturbations influence flight control and energetic expenditure is essentially unknown. Here, we evaluate the kinematic and metabolic consequences of flight within variably sized vortex shedding flows using five Anna's hummingbirds feeding from an artificial...