READ ME File For 'Bubble dynamics in the absence of lipid crystallisation'

Dataset DOI: 10.5258/SOTON/D2111

ReadMe Author: Jack Youngs, University of Southampton ORCID ID: https://orcid.org/0000-0001-7096-4532

This dataset supports the thesis entitled: Understanding bubble dynamics within sonicated edible lipids to enhance their physicochemical properties.
AWARDED BY: Univeristy of Southampton
DATE OF AWARD: 2022

DESCRIPTION OF THE DATA
Over the past decade several studies have reported the use of high intensity ultrasound (HIU) to induce the crystallization of lipids. The effect that HIU has on lipid crystallization is usually attributed to the generation of cavities but acoustic cavitation has never been fully explored in lipids.  The dynamics of a particular cavitation cluster next to a piston like emitter in an oil, was investigated in this study.  The lipid systems, which are important in food processing, are studied with high-speed camera imaging, laser scattering and hydrophone pressure measurements.  A sequence of stable clusters were noted.  In addition, a bifurcated streamer was detected which exists within a sequence of clusters.  This is shown to originate from two clusters on the PLE tip oscillating with an 1800 phase relationship with respect to one another. Finally, the collapse phase of the cluster is shown to involve a rapid (<10 µs) two stage process. These results show that the dynamics of cluster formation and collapse is driven by HIU power levels and might have implications in lipid sonocrystallization.The processing of oils is vital to their ultimate use within the food industry. Control over the physical properties of such materials could be achieved through the application of high-intensity ultrasound (HIU). However the exact mechanism, centered upon acoustic cavitation, is currently unclear. The ring-up of a HIU source in an oil media is studied in the presence and absence of a pre-exsisting bubble population.  High-speed imaging and acoustic measurements within the system is demonstrated to be extremely useful in characterizing the dynamics present under non steady-state conditions.  The behaviour of the clusters generated in the first 1000 ms under these conditions is shown to be significantly different depending on the bubble population. A bifurcated streamer (BiS), originating from a unique bi-cluster event, is only observable in the presence of a bubble population during the ring-up process to higher cluster orders.  In addition, the lifetime of this BiS event is highly temperature dependent and is shown to be a good marker for the viscosity of the oil employed. This data set underpins the research and discussions detailed within the second results chapter (Chapter 4) of the thesis, given the same title for simplicity. Data collected using an oscilloscope or a high-speed camera.  Processed using VB2010 software utilizing NI Measurement studio or, where appropriate, manufacturer supplied software (Photron for example). The data was collected as described in the thesis.  Data is comma delimited as appropriate.

This dataset contains 5 folders (Data 1-4 and High-speed camera data). Each folder contains a sub-folder with the experimental data used for a specific figure reported in the thesis chapter where applicable.

Data 1:
Figure 3.3		Still images showing the gradual erosion of the PLE tip surface and the corresponding bubble behaviour. Example of hydrophone pressure measurements recorded as function of time during this erosion period.

Figure 3.5		Still images taken from high-speed video recorded during PLE tip operation (23 kHz, 32 Wrms) within sunflower oil sample. Used to construct the image grid to be visualised in a raster like fashion.

Figure 3.6		Example of raw hydrophone and light scattering data collected during HIU operation (23 kHz, 32 Wrms) to highlight the dual stage collapse of the cavitation cluster.

Figure 3.7 and 3.10	Origin project file (.opju) detailing the freqeuncy components within the hydrophone pressure data collected during HIU operation at different power levels (23 kHz, 8-32 Wrms). Each power is given by a unique cavitation cluster environment.

Figure 3.8		Examples of microphone and hydrophone data collected when HIU was operating at different power levels, each given by a unique cavitation cluster, recorded under steady state conditions (continuous).

Figure 3.10		.csv files detailing the hydrophone pressure data recorded during HIU operation (20 kHz) at different power levels (3-84 W), each given by a unique cavitation cluster environment (with periodicities f/2, f/3, BiS, f/4, f/5, f/6 and f/7 (where f=20 kHz)).

Figure 3.12		.csv file showing the velocity calculations for liquid flow (linked to the bubble streamer event) in the presence of HIU at different power levels (8-32 Wrms)

Data 2:
Figure 3.13		F1 file containing the hydrophone and light scattering data recorded during HIU operation in the absence of pre-existing bubble population which was processed via FFT analysis. This is combined with the high-speed video used to visualise the bubble behaviours as a function of time to correlate to different acoustic emissions.

Figure 3.14		F2 file containing the hydrophone and light scattering data recorded during HIU operation in the presence of pre-existing bubble population which was processed via FFT analysis. This is combined with the high-speed video used to visualise the bubble behaviours as a function of time to correlate to different acoustic emissions.

Figure 3.15		Examples of microphone and hydrophone data collected when HIU was initiated at different final power level settings, showing the transition between each intermediate cavitation cluster environment as a function of time, before the final cluster formed. Data acquisition was triggered by the step change in the hydrophone signal as the PLE tip was first initiated.

Figure 3.17		Still images taken from high-speed video recorded during PLE tip operation (23 kHz, 11 Wrms) within sunflower oil sample. Used to construct the image grid to be visualised in a raster like fashion. 

Figure 3.18		Still images taken on digital SLR camera as the PLE tip was rotated in 90 degree increments to visualise the reproducible location of the bifurcated streamer event on the PLE surface. 

Data 3: 
Figure 3.19, 3.21, 3.22		Raw data including the hydrophone pressure measurements (vs. time) as the PLE tip was repeatedly pulsed for short periods (1 second intervals) to determine the acoustic emission and behaviour of the BiS event during the PLE ring up process to higher power levels. Analysis of this data was conducted to obtain the average start and end time and the overall lifetime of the BiS event as a function of temperature. This was compared to the changes in the liquid viscosity over this temperature range.

Data 4:
Figure 3.23		Raw data detailing the hydrophone measurements recorded as a function of time to identify whether the presence of the BiS event was dependent upon the (delay) time that HIU was switched off before it was re-initiated. 

Figure 9.3 and 9.4	PLE tip displacement data for both of the ultrasonic sources (20 kHz and 23 kHz) at a range of HIU power levels, each given by a unique cavitation cluster event.

Figure 9.9		.csv file detailing the liquid viscosity data for a range of different edible oils recorded as a function of temperature.


The high-speed data folder includes sub-folders containing the .avi files used to generate Figure 3.17 (BiS thesis), Figure 9.6 (f3 thesis), Figure 9.7 (f4 thesis) and Figure 9.8 (f5 thesis). This is accompanied by examples of still images taken from each of the videos.


Date of data collection: 01/08/2017 to 01/10/2020

Information about geographic location of data collection: University of Southampton, U.K. and Utah State University, U.S.

Licence:
CC-BY

Related projects/Funders:
This project was supported by Agriculture and Food Research Initiative (AFRI) Grant No. 2017-67017-26476 from the USDA National Institute of Food and Agriculture, Improving Food Quality–A1361.

Related publications:
Title: Cavitation Clusters in Lipid Systems: The Generation of a Bifurcated Streamer and the Dual Collapse of a Bubble Cluster
DOI/Handle/URI: 10.1002/aocs.12283

Title: Cavitation clusters in lipid systems - Ring-up, bubble population, and bifurcated streamer lifetime
DOI/Handle/URI: 10.1016/j.ultsonch.2020.105168 


Date that the file was created: January, 2022