“…Reviewing the available strategies for solving PDEs in unbounded domains, we find a variety of methods having various degrees of accuracy, flexibility and sophistication. However, most of the existing methods rely -either on an integral representation of the exact solution and the use of Boundary Elements (see, e.g., [15,22,23,32,[34][35][36]); -or on replacing the unbounded domain by a sufficiently large bounded domain enclosed by a Perfectly Matched Layer (PML) (see [5,6]), or on the boundary of which an artificial boundary condition is prescribed; -or on a polar expansion of the solution like in spectral methods (see, e.g., [12,24]) or in infinite elements methods (see, e.g., [7,11,16,18,19,28]). …”