Characterization of acoustic cavitation in liquid-solid systems

Acoustic cavitation is the growth and collapse of microbubbles under the influence of a sound field crossing a liquid. The high local temperatures (up to 10^4 K) and pressures (hundreds of atmospheres), combined with rapid cooling (above 1010 Ks-1), provide a unique environment to promote mechanical and chemical processes. For this reason ultrasound has recently found application in several industrial sectors including industrial cleaning, emulsification, material synthesis, and fermentation.
The cavitation bubbles can be characterized by the dynamics of their oscillations, the maximum temperatures and pressures reached when they collapse, as well as by the numbers of radicals generated. The present project focuses on the quantification of the mechanical and chemical effects in liquid-solid systems, where bubbles grow around small solid inclusions. Liquids will include water and different organic solvents while solids will include powders of different granulometry, with application in heterogeneous catalytic reactions.

Though fundamental, this research project has the potential to contribute significantly and rapidly to the advancement of knowledge in several technical areas such as: material synthesis, electrochemistry, environmental remediation, industrial cleaning, food technology, therapy (medical imaging), and drug delivery.
Fundamental understanding of the physical and chemical processes involved will be acquired through small-scale tests in controlled conditions. From these results, a model that correlates the physico-chemical properties of different cavitating systems with the collapse pressure, the volume of cavitation, the radius of the imploding bubbles and the cavitational yield will be developed.
At Polytechnique Montréal, the academic supervision team will include Prof. Etienne Robert (Mechanical Engineering Dept. – fluid mechanics, modeling) and Prof. Daria C. Boffito (Chemical Engineering; - sonochemistry, process intensification, and catalysis).

Description of position
One PhD position is available, with starting date in winter/spring 2018. Other graduate positions may become available in 2018. The research activities planned are:
1. Experimental characterisation of the cavitating systems using advanced diagnostic means: sonoluminescence, sonochemiluminescence, calorimetry, iodimetry, high- speed imaging and shockwave detection. This position requires aptitudes for laboratory work and a strong background in fluid mechanics, chemistry or physics.
2. Modeling of the acoustic cavitation characteristics of liquid-solid systems. Programing and simulation experience is a strong asset for this position.

Qualifications
The required background for these positions is a Master of Science (MSc or equivalent). Candidates with diplomas in mechanical, physical, chemical or material engineering will be preferred. Excellent communication skills in technical English (both oral and written) are essential. The selection process will be made on the basis of academic merit, language skills and publication record. The applicants must be strongly motivated for graduate studies and be able to work independently towards the objectives of the project.