  We perform unsteady three-dimensional direct numerical simulations to study
the aerodynamic characteristics of finite-aspect-ratio swept wings with a NACA
0015 cross-section at a chord-based Reynolds number of 400. The effects of the
sweep angle ($\Lambda=0^{\circ}-45^{\circ}$) on the aerodynamic force
coefficients are examined for finite-aspect-ratio wings ($sAR=0.5$, 1, and 2)
over a wide range of angles of attack ($\alpha=0^{\circ}-30^{\circ}$). The
unsteady laminar separated flows exhibit complex aerodynamic characteristics
with respect to these parameters. The introduction of sweep enhances lift for
wings with low aspect ratios of $sAR=0.5$ and 1, due to the lift generated by
the vortical structures near the midspan. For these cases, the dependence of
drag coefficients on the sweep angle is less noticeable, particularly at lower
angles of attack. The lift-to-drag ratios for low-aspect-ratio wings increase
with the sweep angle. However, such favorable effects of sweep angle on the
lift coefficients and lift-to-drag ratios are not observed for wings with
higher aspect ratios, where the midspan effects are relatively weaker over the
wing span. The results herein provide a laminar aerodynamic characterization of
the low-aspect-ratio wings and complement the unsteady low-Reynolds-number
aerodynamic database with highlight on the effect of sweep.
