Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: daixieit

Advanced Ultrasonics ENG5316

Coursework Project Descriptions

Project 1: Bubble modelling 

Cavitation bubbles are challenging to investigate experimentally. As such, the scientific literature is rather dominated by simulations of bubble dynamics, via a number of models, with various adaptations to account for a wide range of conditions (including ultrasonic driving, hydrodynamic environments and stabilising shells – in the case of contrast agent microbubble).

The most established model is based on the Rayleigh-Plesset (R-P) equation. This is a non-linear ordinary differential equation relating bubble dynamics to liquid properties and pressure terms.  

Students taking this project will solve the R-P equation (in Matlab, or equivalent). Options for investigation include parametric analysis (of the influence of viscosity, for example), non-linear bubble response, or comparison to experimental observations (undertaken in the Cavitation Research Laboratory).

Learning outcomes:

· Bubble theory & simulations

· Parametric analysis

· Non-linear bubble dynamics

· Coding experience

· Cavitation and applications

Further reading:

The Acoustic Bubble, T. G. Leighton (Academic London, 1994)

Lauterborn & Kurz, Physics of bubble oscillations, Rep. Prog. Phys., 73 106501, 2010

Project 2: Measuring non-linear cavitation emission

Measurement of a linear ultrasonic signal is relatively trivial. Detection is undertaken with an appropriate hydrophone, at the relevant position relative to the source. Application of a calibration coefficient – at a single value of frequency – to the voltage output from the hydrophone, retrieves the pressure measurements.

Non-linear waveforms such as acoustic cavitation noise, however, will have content across multiple frequency values. Assessment of the non-linear content is critical for many applications, with tissue absorption being highly frequency dependent, for example.

Cavitation emission data from an ultrasonic horn {1], and contrast agent microbubbles driven by focused ultrasound [2] (along with broadband needle hydrophone calibration data), will be available on the Moodle. Your project will be to process and analyse one (or more) of these datasets. The first step will be to generate a spectrum of the emissions, to evaluate non-linear components. Subsequent options include characterisation of the cavitation activity, including in reference to applications research from the literature, and assessment of detector-effects relevant to the experiment.

Learning outcomes:  

· Non-linear cavitation emissions

· Assessing frequency content

· Hydrophone calibration and uncertainties

· Hydrophone deconvolution

· Appropriate reporting of nonlinear measurements

Relevant papers:

[1] L. Yusuf, M. Symes & P. Prentice 2021. Characterising the cavitation activity generated by an ultrasonic horn at varying tip-vibration amplitudes. Ultrasonics Sonochemistry, 70 105273.

[2] J. H. Song, A. Moldovan & P. Prentice 2019. Non-linear acoustic emissions from therapeutically driven contrast agent microbubbles. Ultrasound in Medicine & Biology 45(8), pp 2188-2204.