Researches on Nonlinearity of Acoustic Parameters in Biomaterial Extraction with Ultrasound

Sonication is one of effective and economical techniques for biomaterial processing in a lot of fields. Chinese traditional medicine extraction assisted with power ultrasound is one of the innovative techniques nowadays in point of fact. An important need is that the ultrasonic intensity must be strong and symmetrical in all over the acoustic field within the large-scale ultrasonic kettles for engineering practice. However the nonlinearity of the acoustic characteristics makes the distribution of ultrasonic energy in the ultrasonic processor asymmetrical in 4 dimensions D (x, y, z, t). So, the nonlinearity of the spatial and temporal vicissitude of acoustic characters in the bulky ultrasonic kettle must be realized and dealt with seriously. In the paper, the topics involve: (1) To analyse some description methods of nonlinearity; (2) To research on some nonlinear rules about the acoustic parameters of ultrasonic propagation in the mixture of biomaterials and mediums; (3) To make experiments on nonlinearity of acoustic cavitation and sonication yield in fluids. There are 3 aspects introduced in the paper: (1) Besides the rules of wave propagation, some nonlinear relations of momentum for the motion of fluids are discussed, and the second order acoustic nonlinearity parameter B/A of fluids is introduced too; (2) A new free from paraxial approximation and computationally efficient numerical algorithm capable of predicting 4D acoustic fields in lossy and nonlinear media from arbitrary shaped sources is described. (3) The nonlinearity of the spatial distribution of cavitation activity generated within an ultrasonic processing vessel is studied. Based on the researches above, an applied biomaterial extraction vessel has been set up for Chinese traditional medicine extraction manufacture. It was proved that the researches in the paper are rational, effective and useful for biomaterial extraction with ultrasound.