Acoustic streaming in a solid-liquid mixture and microbubbles-liquid mixture caused by ultrasonic wave irradiation

本项目的目的是澄清固体颗粒，微气泡，声流的情况下，照射超声波到固液两相混合物或微气泡-液体混合物与圆板超声换能器的基本现象。数值分析需要这些信息。结果表明：尼龙颗粒和自来水混合物中的声流类似于液体中的声流，称为Eckart流（声流）。另一方面，微泡和水的混合物中的微泡和声流的行为被超声频率极大地改变。这是由圆板超声换能器的方向性来解释的。微气泡受到声辐射力的影响，并不总是跟随液体流动。因此，必须分别分析液体和微泡。

The purpose of the present project is to clarify fundamental phenomena of solid particles, microbubbles, and acoustic streaming in the case of irradiating ultrasonic waves onto solid-liquid two-phase mixtures or microbubbles-liquid mixtures with a circular plate-ultrasonic transducer. The information is needed for numerical analyses. The following results were obtained : Acoustic streaming in a mixture of nylon particles and tap water resembles that in liquid streaming, so called Eckart flow (acoustic streaming). On the other hand, the behavior of microbubbles and acoustic streaming in a mixture of microbubbles and water were greatly changed by the ultrasonic frequency. This was explained by the directionality of a circular plate-ultrasonic transducer. Microbubbles were affected by the acoustic radiation force and did not always follow the liquid flow. Hence, one must analyze liquids and microbubbles separately.