|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
|
Fig. 12. Proposed 3D vortex structure around a swimming bluegill sunfish. Vortex
loops are shed off the caudal, dorsal and anal fins, shown in green, red and
blue, respectively. Vortex filaments and their directions are shown by solid
arrowheads. The direction of vortex rotation, derived by the right hand rule
from the filament direction, is shown with open arrowheads where there is
space. (A) 3D view, showing the proposed linkages between caudal fin tip
vortices and dorsal and anal fin vortices. Question marks are shown where the
connection between dorsal or anal fin vortices and the caudal fin wake is
unclear. The notch vortices in the far wake are shown by dotted lines,
indicating that the structure is hydrodynamically unstable and may not persist
in the form shown. A projection of the vortex structure in the horizontal
plane is shown below, with dotted lines indicating the correspondence between
the projection and four centers of rotation. Note that the projection is taken
from multiple horizontal planes. A midline tracing, in the correct phase, is
shown below the fish. (B) Side views of the vortex filaments shown in A as the
fish swims from left to right, showing how the dorsal and anal fin vortex
filaments could potentially join up to the caudal fin vortices. Notch vortices
in the far wake are again shown dotted to indicate their instability. (C)
Schematic of the progression of the outer dorsal fin vortex and its
interaction with the caudal fin, shown at three points in time from top to
bottom. The fish is holding station in flow moving from right to left. L, low
pressure zones that would be formed along the tail due to the proximity of the
outer dorsal fin vortex.
|
