Based on the wave diffraction theory in the two-layer fluid

and with the use of eigenfunction method

the wave potentials of ocean surface wave and internal wave diffraction in two-layer fluid caused by arc-shaped bottom-mounted breakwater are derived

and accordingly the wave forces and moments on breakwater are analytically calculated. The result shows that in two-layer fluid

the maximum dimensionless wave loads caused respectively by surface wave and internal wave may have the same order of magnitude. The relative variation of incident wave angle

two layer fluid density ratio

sea water condition and breakwater structure geometry condition may have some influence on diffracted wave effects

and there are some differences between the variation of surface wave effect and that of internal wave effect Because of interference from internal wave

the diffracted effects of surface wave in two fluid are different from that of surface wave in uniform ocean.