Dispersive partial differential equations are generally defined on an unbounded domain. When constructing a numerical scheme, it is therefore mandatory to extract a bounded computation domain and set boundary conditions. The derivation of suitable boundary conditions is therefore of paramount importance to obtain a solution that is the restriction of the existing solution on the initial unbounded domain. In this presentation, we will examine the different ways of obtaining so-called transparent boundary conditions and explain how to approximate them to obtain converging numerical schemes.