On waves of particulate phase pressure in granular materials

The speed of propagation U of an infinitesimal one‐dimensional disturbance of particulate phase pressure in dry granular flow is analyzed. We regard the propagation of such a discontinuity as the analog of the speed of sound in the classical continuum theory. Indeed, we show that, on the basis of the pseudo‐thermodynamic theory of granular flow which we have recently presented, U is the square root of the inverse iso‐pseudo‐entropic compressibility of the particulate phase. Direct calculation of the value of U is discussed.