  Through triglobal resolvent analysis, we reveal the effects of wing tip and
sweep angle on laminar separated wakes over swept wings. For the present study,
we consider wings with semi-aspect ratios from $1$ to $4$, sweep angles from
$0^\circ$ to $45^\circ$, and angles of attack of $20^\circ$ and $30^\circ$ at a
chord-based Reynolds number of $400$ and a Mach number of $0.1$. Using direct
numerical simulations, we observe that unswept wings develop vortex shedding
near the wing root with a quasi-steady tip vortex. For swept wings, vortex
shedding is seen near the wing tip for low sweep angles, while the wakes are
steady for wings with high sweep angles. To gain further insights into the
mechanisms of flow unsteadiness, triglobal resolvent analysis is used to
identify the optimal spatial input-output mode pairs and the associated gains
over a range of frequencies. The three-dimensional forcing and response modes
reveal that harmonic fluctuations are directed towards the root for unswept
wings and towards the wing tip for swept wings. The overlapping region of the
forcing-response mode pairs uncovers triglobal resolvent wavemakers associated
with self-sustained unsteady wakes of swept wings. Furthermore, we show that
for low aspect ratio wings optimal perturbations develop globally over the
entire wingspan. The present study uncovers physical insights on the effects of
tip and sweep on the growth of optimal harmonic perturbations and the wake
dynamics of separated flows over swept wings.
