Direct numerical simulation of unsteady finite-span hydrofoil flow

The tip-vortex flow over a finite-span hydrofoil with laminar separation on the hydrofoil surface was numerically studied by computing the three-dimensional unsteady Navier-Stokes equations. The computations were direct numerical simulations of all resolvable structures without adding a turbulence model. The topological structure of unsteady separated flow and the influence of the unsteady laminar separated flow on the tip vortex for both swept and unswept hydrofoils were qualitatively investigated. The secondary flow induced by the swept planform played an important role in the unsteadiness of the tip vortex. The interaction between the tip vortex and the unsteady laminar separated flow became stronger as the sweep angle was increased.