Acoustic slow waves and the consolidation transition

摘要: We have investigated the ultrasonic properties of unconsolidated (loose) glass beads and lightly fused (consolidated) when pore space is saturated with water. At a frequency 500 kHz we observed single compressional wave in former whose speed 1.79 km/s two distinct waves speeds 2.81 0.96 latter. The Biot theory shown to give an accurate description this phenomenon. also analyze acoustics low temperature He ii packed powder superleaks; either fast for systems or slow highly consolidated (fused) frame may be considered 4th sound mode. In all such systems, acoustic can very simply understood by considering velocities propagation as continuous functions elastic moduli solid skeletal frames.