Photoacoustic shock generation in carbon suspensions

This letter discusses photoacoustic shock wave generation and the origin of nonlinear sound wave generation in carbon suspensions. The Burgers equatio n for an inviscid fluid is solved for an exponential acoustic wave. The sol ution shows an increasingly steep wave form that gradually coalesces into a shock front. Large dynamic range measurements of photoacoustic waves gener ated by a pulsed-laser beam in carbon suspensions show the pressure in the wave to depart significantly from the predictions of linear response theory . Acoustic sound speed and amplitude measurements indicate that weak shocks are produced from the photoacoustic sound generation process rather than f rom nonlinear propagational effects. (C) 1999 American Institute of Physics . [S0003-6951(99)02452-3].