Abstract: KCS standard ship model was studied as the object of this paper. The numerical calculation by using Reynolds Averaged Navier-Stokes method is mainly for the variation of the constraint model’s nominal wake field in a short regular wave encounter period, and its features are analyzed. The calculation results show that time history of axial nominal wake fraction is the same as the periodic variation of the incident wave. The variation of the wave wake fraction in a single wave period is relatively small, however, the impact of wave cannot be ignored. The main cause of wave wake fraction in negative value is the wave drift in the direction of the wave direction, which approximately equals to the total average flow. When the wave crest and wave trough is located at the propeller disk, axial nominal wake field change is always the most obvious, and the degree of change significantly affected by the wave steepness, and the decreases of wave length has a certain influence on the below of the propeller disk.

Key words: nominal wake field, short wave, wake fraction, wave wake field, Stokes drift current, numerical calculation