Effect of Applied Low-Frequency Sound on Promotion of Mixing and Mixing Mechanism in a Rectangular Pipe Liquid Flow

Abstract

Lower-frequency sound was applied to a liquid flow in a rectangular pipe and the effects of the sound on the promotion of mixing and the mixing mechanism were investigated experimentally. It was found that the micro scale based on concentration fluctuations and the intensity of concentration fluctuations of the tracer became smaller and the mixedness increased when the sound was applied. The same usefulness of applied sound for the promotion of liquid mixing in a circular pipe was confirmed and the possibility of developing an in-line liquid mixer using sound was shown. It was confirmed that the micro scale based on concentration fluctuations, intensity of concentration fluctuations and mixedness were closely connected with one another and that mixing progressed as these indices kept their mutual relations. Additionally, it was found that the change of mixedness with time could be estimated by using the energy spectrum distribution of velocity fluctuations, and that the initial rate of mixing was in proportion to the volume of the space micro scale eddy based on velocity fluctuations.