When hydraulic machinery start to operate, the flow around the blades has to be transient, so that hydraulic losses have to come out within very specified regions transiently. To clarify such behavior of the losses, we take up a typical vortical flow around a highspeed hydrofoil and numerically simulate such transient behavior of the losses arisen around the foil, especially near the stagnation point, the backward separation region and the trailing edge. Even within the transient : range, the boundary layer develops on the entire foil surface and the starting vortex sheds off from the trailing edge, in the manner of pseudo-potential response. The losses limitedly appear around the above-mentioned regions, but the wake accompanying with Karman vortices scarcely appears.
