The measurements of the separated vortex field and forces for drag plate show that the nose up pitching moment is produced due to the large induced downwash angle from the separated vortices of drag plate at the tail.

The computed results show that if the ratio between blade local thickness and clearance highness is too large or too small, the separation vortex will generate difficultly, and under the condition of rotating hub the separation vortex in tip region will gene.

Finite Volume method was used to solve the three dimensional Navier Stokes equations of ideal gas,and combine flux conservative patched method and B L turbulence model correction to study this problem,capturing fluid field informations such as separation vortex,shock wave,expansion wave.

Comparisons of a) the location of the vortex core, b) strength of separated vortex, c) pressure distribution on the surface, d) forces and moments, e) turbulence viscosity ratio with experimental results indicat that all three k-ε models can simulate the separa.

In order to consider the effect of separated vortex on lateral hydrodynamic forces acting on a yawing ship,this paper gives a new free surface condition which includes the effect of vortex and puts forward a new concept of “vortex factor”.

This paper puts forward a new free surface condition taking account for the “effect factor of vortex” in order to study the effects of the separated vortex on maneuvering hydrodynamic forces.