Wake structure and kinematics in two insectivorous bats
Abstract
We compare kinematics and wake structure over a range of flight speeds (4.0–8.2 m s−1) for two bats that pursue insect prey aerially,Tadarida brasiliensisandMyotis velifer. Body mass and wingspan are similar in these species, butM. veliferhas broader wings and lower wing loading. By using high-speed videography and particle image velocimetry of steady flight in a wind tunnel, we show that three-dimensional kinematics and wake structure are similar in the two species at the higher speeds studied, but differ at lower speeds. At lower speeds, the two species show significant differences in mean angle of attack, body–wingtip distance and sweep angle. The distinct body vortex seen at low speed inT. brasiliensisand other bats studied to date is considerably weaker or absent inM. velifer. We suggest that this could be influenced by morphology: (i) the narrower thorax in this species probably reduces the body-induced discontinuity in circulation between the two wings and (ii) the wing loading is lower, hence the lift coefficient required for weight support is lower. As a result, inM. velifer,there may be a decreased disruption in the lift generation between the body and the wing, and the strength of the characteristic root vortex is greatly diminished, both suggesting increased flight efficiency.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 26, 2016
- Source ID
- 10.1098/rstb.2015.0385
Entities
People
- Kenneth S. Breuer
- Nickolay I. Hristov
- Sharon Swartz
- Tatjana Y Hubel
Organizations
- Air Force Office of Scientific Research
- Brown University
- National Science Foundation
- Royal Veterinary College, University of London