Lombard Olivier, Viard Nicolas, Leroy Valentin, Barrière Christophe
Laboratoire MSC, Université Paris-Diderot, CNRS (UMR 7057), Paris, France.
Institut Langevin, Université Paris-Diderot, ESPCI, CNRS (UMR 7587), Paris, France.
Eur Phys J E Soft Matter. 2018 Feb 8;41(2):18. doi: 10.1140/epje/i2018-11624-9.
This experimental study deals with the propagation of an ultrasonic shock wave in a random heterogeneous medium, constituted of identical 75μm radius bubbles, trapped in a yield-stress fluid. The fundamental frequency of the incident wave (in the MHz range) was much larger than the resonance frequency of bubbles (38kHz). A well-expanded coda, resulting from the multiple scattering of the incident shock wave through the heterogeneous medium, was experimentally measured in transmission. Despite the significant amplitude of the shock wave (90kPa), no sign of nonlinear response of the bubbles was detected. Both the coherent and incoherent fields were successfully described by linear theories. Using a shock wave presents the advantage of characterizing the medium over a large frequency range (1.5-15MHz).
本实验研究了超声冲击波在由半径为75μm的相同气泡构成的随机非均匀介质中的传播情况，这些气泡被困在一种屈服应力流体中。入射波的基频（在兆赫兹范围内）远大于气泡的共振频率（38kHz）。通过透射实验测量了由入射冲击波在非均匀介质中多次散射产生的扩展良好的尾波。尽管冲击波的幅度很大（90kPa），但未检测到气泡非线性响应的迹象。线性理论成功地描述了相干场和非相干场。使用冲击波具有在大频率范围（1.5 - 15MHz）内表征介质的优点。
