Impact of trailing edge shape on the wake and propulsive performance of pitching panels

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

“…This is consistent with the experimental measurement on a flat plate at Re = 6000 and 10,000, which showed that a convex fin with a smaller AR is relatively more efficient. 10 By contrast, when studying the propulsion mechanism of lamprey and jellyfish, Gemmell revealed that animals could pull themselves through the water by suction, and this suction-based propulsion is more efficient than the pushing-based mechanism. 37 In the study of Gemmell et al, the propulsive mechanism of lampreys and jellyfish is altered by spinal transect, which maintains the geometry but changes the kinematics.…”

“…9 Van Buren used the digital particle velocimetry (DPIV) technique to quantify the flow field and found that as the trailing edge shape changed from convex to concave, the efficiency as well as the thrust decreased significantly. 10 Feilich et al used a mechanically-actuated flapping foil model to study how the shape and caudal peduncle depth affect different aspects of swimming performance. They found that there was no single optimal foil exhibiting the highest performance in all metrics.…”

Effects of Geometric Porosity in the Trailing Edge of a Flexible Pitching Plate

“…The propulsive performance of pitching plates are also affected by the trailing edge geometry. η and C t increase as the trailing edge transitions from a concave chevron cut, square cut, and convex chevron cut respectively [8]. The wake compression is enhanced in the convex cuts, as the fluid in the trailling wake separates into four smaller jets moving away from the centreline, which increase the momentum in the wake [8].…”

“…This numerical investigation seeks to quantify the effects of porosity on pitching flexible plates, by continuing the work of Van Buren et al [8]. The individual pore controls the magnitude and location of communication between the upper and lower pressure regions, with the pore diameter set at 0.07C, and the location shifted in 0.05C increments between 0.725C and 0.925C, where C is the chord of the plate (Figure 1).…”

“…η and C t increase as the trailing edge transitions from a concave chevron cut, square cut, and convex chevron cut respectively [8]. The wake compression is enhanced in the convex cuts, as the fluid in the trailling wake separates into four smaller jets moving away from the centreline, which increase the momentum in the wake [8]. While there has not previously been investigations into porous pitching plates, principles can be drawn from porous aerofoils.…”