Generally, random waves are generated by a serpent-type wave maker for a representative offshore wave spectrum determined with spectral and directional functions. Moreover, its transformation in shallow water are reproduced on a bathymetry model installed in physical, however, its range is restricted with both an area of the wave basin and an applicable model scale considering the scale effect. Therefore, it may be much effective to expand the wave test area in virtual. To do this, the transformed random waves are generated with deformed and spatially distributed directional spectra estimated by using energy balance equation model in this paper.
Though the wave heights and periods generated by the newly installed generation method are little smaller than ones generated by the normal method due to revised target directional spectra, wave diffraction behind a virtual breakwater in offshore can be reproduced without any physical experimental model. Therefore, it is expected that the newly improved wave maker can expand the offshore boundary of test area in virtual, which is restricted due to the size of the physical basin. However, it is difficult to reproduce wave refraction on a virtual spherical shoal because the nonlinear effects in deformed directional spectra estimated by using energy balance equation model must be not considered.

Key Words: serpent-type wave maker, multi-directional wave, shallow water, wave transformation