Phase difference and interference between reflected cylindrical wave and head wave at a liquid/solid interface

The reflected field of pulsed cylindrical waves from a liquid-solid interfa ce is studied by the numerical method and the experimental method. The refl ected field is calculated and shown in gray pictures. The calculated incide nt angles theta (n) (n = 1, 2, 3,...) of a series of minimums (or nulls) on the reflected wavefront are presented. The measured angle of the minimum f rom Schlieren photograph is consistent with that by calculation. The appear ance of minimums is explained by the interference between the reflected wav e and the head wave, and by the radiated dissipation of the head wave. The leading phase angle of the head wave to the reflected wave is proved to be about 3 pi /4 by the numerical calculation.