Effect of curvature and angle of attack on the hydrodynamic performance of a tapered harbor seal whisker

Harbor seals rely on their whiskers, which have a unique surface morphology, to track prey. However, previous studies have primarily focused on the whisker's undulatory features, while the effects of taper and curvature on the hydrodynamic performance remain largely unexplored. This paper establishes a parameterized surface function for the harbor seal whisker, incorporating its undulation, taper, and curvature characteristics. High-fidelity CFD (computational fluid dynamics) simulations are conducted to systematically investigate effects of curvature, including a straight reference model and four tapered configurations with increasing curvature (A1–A4) across six angles of attack (AoAs) ranging from 0° to 75°, on the hydrodynamic performance of harbor seal whiskers. Results show that curved and tapered whiskers reduce mean drag and lift across all angles of attack, with drag lowered by approximately 30%–40% and unsteady force fluctuations suppressed by up to an order of magnitude at zero incidence. Unlike the straight model, they maintain weak, broadband spectra with only small peaks at moderate AoA, and vorticity visualizations reveal disrupted spanwise coherence and fragmented wakes, most pronounced for the highest-curvature model. These findings highlight how key morphological features of seal whiskers, including undulation, taper, and curvature, work together to suppress force oscillations and enhance hydrodynamic sensing across a range of AoAs, offering valuable guidance for the bio-inspired design of flow sensors in aquatic applications.