Head-on Collision Between Two Envelope Solitary Waves in a Granular Medium

We investigated the head-on collision between two envelope solitary waves. Head-on collisions between two envelope solitary waves are first discussed in one-dimension (1D) granular chains. The interesting result is that no phase shift or phase delay detected after the head-on collision between two envelope solitary waves. The maximum amplitude during the head-on collision between two envelope solitary waves is also found to be less than the sum of the amplitudes of the two envelope solitary waves, but is larger than the amplitude of the either of the envelope solitary waves.