COMPUTATION OF UNSTEADY FLOWFIELD OVER A HYDROFOIL, INCLUDING BOUNDARY-LAYER AND WAKE

A time-accurate, two-dimensional, semi-implicit pressure-based Navier- Stokes solver for incompressible flows is used to carry out the numeri cal simulation of the unsteady Bow over a hydrofoil, A low-Reynolds-nu mber form of the two-equation turbulence model is used to account for the turbulence effects. To improve the accuracy of the numerical schem e, a central differencing plus artificial dissipation scheme is implem ented to provide a precise control of the numerical dissipation, An in ner-loop iteration scheme is used at each time step to account for the nonlinear effects, The information on the upstream time-dependent flo w is specified from the experimental data. The results show that the c haracteristics of the unsteady boundary layers along the foil surfaces are predicted very well by the numerical method, including the amplit ude of the velocity fluctuation and the phase angle changes as well as Bow features near the surfaces. The instantaneous flowfield is presen ted at various locations along the hydrofoil surfaces and downstream o f the hydrofoil, Both the computational and experimental results are i nterpreted to improve physical understanding of the flow phenomena ins ide unsteady boundary layers.