Heat generation by ultrasound in a relaxing medium

Abstract

At any point P in a continuous sound field the time-averaged rate of heat generation by relaxational absorption per unit volume is given by ap02/.rho.c. Here p0 is the pressure amplitude at P while a is the absorption coefficient arising from relaxation when the coefficient of shear viscosity .eta. is zero; .rho. and c are, respectively, the density and velocity of sound in the medium. The result, a familiar one for plane traveling waves, is shown here to apply generally when .eta. = 0.