Numerical Investigation of Fluid Flow Past a Hydrofoil in Free Surface Condition

Hydrofoil is an important structure for high speed craft. In construction of hydrofoil, we use NACA series. To optimize the hydrofoil efficiency, we have to determine the hydrofoil position from free surface of the flow. Position of hydrofoil from free surface affects the hydrofoil structure significantly. So, when we optimize hydrofoil efficiency by reducing drag, the stress of the hydrofoil changes, therefore we obtain a close relationship between drag of the craft and position of hydrofoil. In case of hydrofoil an interesting case occurs when the foil moves in close proximity of the air water interphase i.e. free surface case. In this case the forces (lift and drag) show nonlinearity with Froude number. Moreover, the sustainability of the moving hydrofoil is also affected by the change of depth.This paper is concerned how the dynamic condition affects the structure of moving hydrofoil due to free surface case.