Emergence of unsteadiness in the flows around archery bare-shaft arrow

Abstract

Numerical simulation was performed for the flows past an archery bare-shaft arrow at small attack angles. The Reynolds number Re based on the shaft diameter was varied between 1.0 x 10⁴ and 2.0 x 10⁴, and the attack angle was varied from 0 degrees to 1.4 degrees. Computations were carried out for bare-shaft arrows with two different kinds of arrow point, i.e. streamlined point and bulge point. The behavior of the boundary layer along the arrow shaft was extensively studied by means of post process visualization. According to the excerpt extracted from the results of parametric study, it was confirmed that the boundary layer flow maintains steady state for a part of the parameter plane studied. Furthermore, it was remarked that, for the arrow with bulge point at high Re, unsteady motion was triggered by separation bubble in the vicinity of arrow point, while at low Re, unsteady motion was initiated by the emergence of low-speed wave-like structure near the arrow tail on the back side of the shaft.