Incident wave
= Incident wave
{title2=$\psi_i$}
= Incident field
{synonym}
The <incident wave> is the prescribed background solution that illuminates a scatterer. It solves the unperturbed <Helmholtz equation> in scalar time-harmonic models. The scattered contribution is defined by subtracting this field from the total field; reflected waves from a planar boundary are included unless a separate reference reflection is explicitly removed.