An improved finite difference scheme is applied to simulate wave propagation in the vicinity of a slot normal to the surface of an elastic half space. It provides visualization of the scattered wave pattern at a sequence of time steps, and also the components of displacement as functions of time at a series of observation points.

After being hit by a normally incident plane P pulse, the slot oscillates with two main cycles and two shear-compressional pairs of diffracted waves, and also Rayleigh pulses, are scattered from it. The resulting wavefronts are parallel to the vertical surfaces of the slot and curve in semicircular arcs around the bottom of the slot.

Experimental tests of the theory were performed, using 0.5-6 MHz ultrasonic pulses on duralumin cylinders with surface-breaking slots ranging from 0.5-2 mm in width and from 2-6 mm in depth. The numerical results were confirmed by these experiments.