Liquid Motion in a Solid-liquid Mixed Region under Imposition of Ultrasound

Abstract

Flow excitation in a solid-liquid mixed region surrounded by a solid layer is not easy because of difficulty of direct exertion of force on the liquid and large apparent viscosity. Ultrasound is expected as a flow excitation tool in the solid-liquid mixed region because it can transmit force from the outside of the surrounding solid layer. Thus, investigation on the liquid motion under the ultrasound imposition on the solid-liquid mixed region has been done in this study. Because of the large difference of acoustic impedance between an alumina and a polyacetal, they were chosen as the solid particles in the solid-liquid mixed region while water was chosen as the liquid. The superficial velocity in the solid-liquid mixed region increased as its length became shorter under the condition that the voltage on the ultrasound vibrator was constant. Apparent porosity under the imposition of the ultrasound was larger than the real porosity evaluated without the ultrasound when the water-alumina system was used, and the former increased as the solid-liquid mixed region length became shorter. On the other hand, the apparent porosity under the ultrasound imposition was only slightly larger than the real porosity without the ultrasound imposition in the case of the water-polyacetal system. The difference between these systems might be caused by the acoustic impedance difference between the alumina and the polyacetal.