MuBeta Laboratory Student Profile


photo-steve photo-steve2

Stephen Dubsky

PhD student
MuBeta Laboratory

Address: DBE, Monash University Clayton
Phone: +61 (0)3 990 51927
Fax: +61 (0)3 990 59724
Email: Email Steve



Qualifications: B.E. (Mech.) Monash 2006, B.T. (Aero.) Monash 2006

PhD topic: Development of correlation based 3-D PIV techniques

Details:
Particle image velocimetry (PIV) is an established measurement technique used to measure velocity fields in fluid flows. In its traditional form, PIV allows for two-component velocity measurements within a plane. A particle seeded fluid is illuminated with a thin laser sheet of visible light, and particle displacement between pairs of images taken at a known time separation is determined using statistical cross correlation techniques. Particle velocity is then calculated by division of the displacement with the image separation time. The requirement of optical access limits the application of this technique in real biological flows, such as those associated with cardiovascular disease. Also, the three dimensional nature of the flow in many biological and engineering applications make these flows difficult to characterise using current PIV analysis techniques.

The recent combination of synchrotron X-ray imaging with PIV offers the potential of three dimensional measurement of flows within opaque objects, such as in the body. Currently, X-ray PIV techniques are limited to two component velocity measurements. The current research involves developing a three component, three dimensional X-ray PIV technique. This technique is based on deconvolution of the cross correlation functions to yield the velocity probability density function of the measurement volume. The three dimensional velocity field can then be reconstructed using this information.

A similar technique is also being developed for three dimensional measurement using visible light illumination. By combining the information provided by the limited depth of focus of the optical imaging system and velocity probability density functions calculated using the cross correlation analysis, the velocity field within a three dimensional volume may be determined. Currently this technique is limited to two components of velocity, however by using multiple camera views the technique can be extended to measure three velocity components.

The three dimensional velocity measurement techniques being developed will provide invaluable tools for research into complex biological and engineering flows. The future application of these techniques in a clinical setting will represent a significant advancement in technology for the diagnosis and treatment of cardiovascular disease.

Paper(s) currently in progress:

  1. Dubsky, S., Fouras, A., Irvine, S.C., Siu, K.K.W. & Hourigan, K. "Three dimensional three component X-ray particle image velocimetry using multiple projections" In preparation for submission to Applied Physics Letters.

Publications:

  1. Andreas Fouras, Beth J. Allison, Marcus J. Kitchen, Stephen Dubsky, Jayne Nguyen, Kerry Hourigan, Karen K.W. Siu, Kentaro Uesugi, Naoto Yagi, Rob A. Lewis, Megan J.Wallace, Stuart B. Hooper (2009) Regional Lung Function measured using X-ray Velocimetry. Submitted.
  2. Kitchen, M.J., Habib, A., Fouras, A., Dubsky, S., Lewis, R.A., Wallace, M.J. & Hooper, S.B. (2009) A new design for high stability pressure-controlled ventilation for small animal lung imaging. Submitted to Journal of Instrumentation.
  3. Irvine, S.C., Paganin, D.M., Jamison, R.A., Dubsky, S. & Fouras, A. (2009) Vector tomographic X-ray phase contrast velocimetry utilizing dynamic blood speckle. Submitted to Optics Express.
  4. Dubsky, S., Jamison, R.A., Irvine, S.C., Siu, K.K.W., Hourigan, K. & Fouras, A. (2009) Computed tomographic X-ray velocimetry. Submitted to Applied Physics Letters.
  5. Fouras, A., Kitchen, M.J., Dubsky, S., Lewis, R.A., Hooper, S. & Hourigan, K. (2009) "The past, present and future of X-ray technology for in vivo imaging of function and form", invited submission to Journal of Applied Physics, 105, 102009: 1–14. Also published in Virtual Journal of Biological Physics Research.
    doi: 10.1063/1.3115643
  6. Irvine, S.C., Paganin, D.M., Dubsky, S., Lewis, R.A. & Fouras, A. (2008) Phase retrieval for improved 3-D velocimetric analysis of X-ray blood flow speckle patterns, Applied Physics Letters, 93, 153901: 1–3.
    doi: 10.1063/1.3001592

Conferences/Seminars:

  1. PDF Download Chua, C.S., Sheard, G.J., Dubsky, S., Higgins, S., Jamison, R.A., Fouras, A. & Hourigan, K. (2009) Particle image velocimetry of non-axisymmetric stenosis models, in Proc. 8th International Symposium on Particle Image Velocimetry — PIV09, Melbourne, Australia, 25–28 August 2009.
  2. PDF Download Fouras, A., Dubsky, S., Nguyen, J., Hourigan, K., Kitchen, M.J., Allison, B.J., Wallace, M.J., Siew, M.L., Siu, K.K.W., Lewis, R.A., Uesugi, K., Yagi, N. & Hooper, S.B. (2009) In-vivo Synchrotron PIV for the measurement of airway motion, in Proc. 8th International Symposium on Particle Image Velocimetry — PIV09, Melbourne, Australia, 25–28 August 2009.
  3. PDF Download Irvine, S.C., Paganin, D.M., Dubsky, S., Lewis, R.A. & Fouras, A. (2009) Phase retrieval for improved multi-dimensional velocimetric analysis of X-ray blood flow speckle patterns, in Proc. 8th International Symposium on Particle Image Velocimetry — PIV09, Melbourne, Australia, 25–28 August 2009.
  4. PDF Download Jamison, R.A., Fouras, A., Dubsky, S., Irvine, S.C., Siu, K.K.W., & Hourigan, K. (2009) Synchrotron X-ray PIV of blood flow in an optically opaque bifurcation model, in Proc. 8th International Symposium on Particle Image Velocimetry — PIV09, Melbourne, Australia, 25–28 August 2009.
  5. Dubsky, S., Fouras, A., Irvine, S.C., Siu, K.K.W. & Hourigan, K., (2008) Three component, three-dimensional X-ray particle image velocimetry using multiple projections, 14th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal, 7-10 July 2008.
  6. PDF Download Fouras, A., Lo Jacono, D., Nguyen, C.V., Dubsky, S. & Hourigan, K., (2008) Volumetric correlation PIV: A new technique for 3D velocity vector field measurement, 14th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal, 7-10 July 2008.

Teaching experience:

  • Tutor: ENG1040 Engineering Dynamics, Monash University Clayton (S1 2009; S2 2009)
  • Tutor: MAE2402 Thermodynamics and Heat Transfer, Monash University Clayton (S2 2008)

Affiliations:

  • Fluids Laboratory for Aeronautical and Industrial Research (FLAIR), Monash University