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

Abstract

Flowexcitationinasolid-liquidmixedregionsurroundedbyasolidlayerisnoteasybecauseofdifficultyofdirectexertionofforceonthe liquidandlargeapparentviscosity.Ultrasoundisexpectedasaflowexcitationtoolinthesolid-liquidmixedregionbecauseitcantransmit 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,theywerechosenasthesolidparticlesinthesolid-liquidmixedregionwhilewaterwaschosenastheliquid.Thesuperficialvelocity 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.