A computational model of pinna tubercle aerodynamics in the fast-flying bat, Tadarida brasiliensis.

Abstract

Irregular leading edge (LE) surfaces can increase the aerodynamic efficiency of airfoils in some situations, although the exact mechanism is debated. The current study assessed the aerodynamic effect of LE tubercles present on the pinna of the fast-flying bat species, Tadarida brasiliensis. Using micro-computed tomography (μCT) to build the pinna geometry and finite volume computational fluid dynamics (CFD), air flow was modeled over a static naturally shaped 3D tubercled pinna and an edited smoothed 3D pinna at various angles of attack (AoA) to assess the aerodynamics of pinna LE tubercles. Model results supported the hypothesis, with the tubercled pinna exhibiting marginally reduced drag at the AoAs leading up to stall and increased lift in the AoAs post stall. This increase in aerodynamic efficiency was due to the generation of streamwise vortices shed off the LE tubercles. These data add to the growing body of literature on naturally occurring LE tubercles and their role in aerodynamic efficiency.