Abstract: The singular behaviour in [he vicinity of intersection between the body and free surface is presented. It is shown that in the linear regime the singularity of velocity potential for transient problem is in d²/nd. The singular behaviour for harmonic problem is the same as the result for the transient problem. In particular, the singularity for the harmonic problem with infinite frequency is in d²/nd for velocity potential (d is the distance between field point and intersection).