We report on the experimental observation of vortex cluster shedding from a moving obstacle in an oblate atomic Bose-Einstein condensate. At low obstacle velocities v above a critical value, vortex clusters consisting of two like-sign vortices are generated to form a regular configuration like a von Kármán street, and as v is increased, the shedding pattern becomes irregular with many different...

The present study dealt with the wall static pressure of a rectangular curved duct with angle of turn 90° at all four faces with various locations. The normalized wall static pressure distributions at the top, bottom, inside and outside surfaces of the C-duct are drawn in the form of contours at three different air velocities, Uav = 20m/s, 40m/s and 60m/s respectively. These iso-bar contours in...

We study experimentally the vortex streets produced by a flapping foil in a hydrodynamic tunnel, using two-dimensional particle image velocimetry. An analysis in terms of a flapping frequency-amplitude phase space allows the identification of (i) the transition from the well-known Bénard-von Kármán (BvK) wake to the reverse BvK vortex street that characterizes propulsive wakes, and (ii) the sym...

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 ...

The ability to detect water flow using the hair cells of the lateral line system is a unique feature found in anamniotic aquatic vertebrates. Fishes use their lateral line to locate prey, escape from predators and form cohesive schooling patterns. Despite the prevalence of complex flows in nature, almost nothing is known about the function of the lateral line and its relationship to other senso...

Motivation. Understanding vector fields is integral to many scientific applications ranging from combustion to global oceanic eddy simulations. Critical points of a vector field (zeros of the field) are essential features of the data, and play an important role in describing and interpreting the flow behavior. However, vector field analysis based on critical points suffers a major drawback: the...