Analysis of wobbling drop video data

(supervisor: Dave Langstaff)

Nature of project: software, data analysis

Available to full-time physicists or joint students.

Project description and methodology

The properties of high temperature liquids may be determined by means of a levitating furnace. In the furnace a small sample is levitated upon a gas jet and heated to high temperature using 2 high power lasers. The temperature of the drop is determined by means of an optical pyrometer. The drop may be stimulated into oscillations (wobbling) by means of an acoustic transducer mounted in the gas feed. The oscillations of the drop are recorded by means of a high speed video camera equipped with a suitable lens. The properties of liquid droplets in free space were studied by Lord Rayleigh in the 19th Century [1].

By measuring the resonant frequency and damping of the oscillations it is possible to determine both the surface tension and the viscosity of the sample.

This project is concerned with analysing the video data of oscillating drops and using appropriate data processing to determine the resonant frequency and damping of the sample. Video analysis will be carried out using any suitable programming language programming or package, such as ImageJ/FIJI, Labview or Python with an appropriate image processing library.

A successful project will develop beyond the above in one/some of the following directions:
From the resonant frequency and damping of the samples as shown in the video recordings, determine the surface tension and viscosity of the sample.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

Additional scope or challenge if taken as a Year-4 project: A 4th year project based on this analysis will be expected to go into more detail and draw conclusions from a number of video files taken at different temperatures.

Initial literature for students:

  1. L. Rayleigh, On the Capillary Phenomena of Jets, Proceedings of the Royal Society of London, 29 (1879) 71-97.
  2. I. Egry, H. Giffard, S. Schneider, The oscillating drop technique revisited, Meas. Sci. Technol., 16 (2005) 426-431.
  3. D.P. Langstaff, M. Gunn, G.N. Greaves, A. Marsing, F. Kargl, Aerodynamic levitator furnace for measuring thermophysical properties of refractory liquids, Rev. Sci. Instrum., 84 (2013) -.
  4. M. Sonka, V. Hlavac, R. Boyle, Image Processing, Analysis, and Machine Vision, Thomson-Engineering 2007.

Novelty, degree of difficulty and amount of assistance required

The project will duplicate analysis that has been carried out within the materials group. The student will need to learn image processing techniques to extract measurements of the sample and then apply filtering and curve fitting to these in order to determine the resonant frequency and damping and hence the surface tension and viscosity of the sample.

Project milestones and deliverables (including timescale)

milestoneto be completed by
Familiarisation with image processing toolkit.end of October
Outline code for video analysisChristmas
Drop size measurements from video dataend of February
Analysis of size measurementsEaster