Date of Award

5-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Mechanical Engineering

Committee Member

Dr. Hongseok Choi, Committee Chair

Committee Member

Dr. Joshua Summers

Committee Member

Dr. Rodrigo Martinez-Duarte

Abstract

Ultrasonic processing of liquids is used in many engineering fields, from sonochemistry to material processing. Acoustic cavitation and acoustic streaming are the two key phenomena responsible for the ultrasonic processing applications. Both of them are non-linear effects of ultrasonic wave propagation in liquids and are extremely hard to characterize either analytically or experimentally. This meant that there is limited knowledge about the interactions between the various parameters that affect the extent of the acoustic cavitation and streaming generated during the ultrasonic processing of liquids. In the current study, it was hypothesized that the geometric configuration of the ultrasonic processing equipment has an effect on the resultant acoustic pressure field, which in turn affects the acoustic cavitation and the acoustic streaming flow. Numerical modeling serves as a powerful tool to overcome the practical difficulties involved in experiments. Over the years, various finite element models have been developed to resolve the acoustic pressure field inside the ultrasonic processing cell. The majority of them have used a linear modeling of the Helmholtz equation with infinitely hard ultrasonic processing cell boundaries. In the current study, a non-linear numerical model was developed to resolve the acoustic pressure inside the ultrasonic processing cell. The viscous dissipation loss during the ultrasonic wave propagation is taken into account by replacing the general liquid material properties with complex material properties in the Helmholtz equation. The model developed was then validated with experimental results. An error analysis revealed that the simulation results show a mean error of about 33 %, with a maximum error of 78 % and a minimum error of 5 % in comparison with the experimental results. Following this, a method was introduced for the quantification of the acoustic cavitation zone size from the numerical modeling results of acoustic pressure field in the ultrasonic processing cell.

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