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Thomas Earl

Thomas Earl photo

BE (Structures)(Hons)
Postgraduate Research Student



School of Civil Engineering
Wind Waves and Water Centre
Phone: +61 2 9351 2116
Fax: +61 2 9351 3343
Email:

Research project - Measurement of Complex 3 Dimensional Turbulent Flows with Tomographic PIV

Supervisor: Dr Steve Cochard
Associate Supervisor: Prof John Patterson

Complex 3-dimensional turbulent flows such as those found behind a wind turbine significantly influences the efficiency of electricity generation. If we can accurately resolve the 3-component 3-dimensional (3C-3D) spatial velocity it will be possible to create a turbulent boundary model enabling us to further understand the helical turbulent model and its effect on downstream turbines.

Tomographic PIV is a state of the art 3D measuring technique. The flow to be measured is seeded with micron-sized particles that follow the fluid motion and a laser is optically modified to illuminate a volume of interest in two discrete time steps. This allows four cameras to capture the particle locations from the laser light that they diffract.

Tomographic particle image Velocimetry

Elsinga et al. (2006). Tomographic particle image Velocimetry. Experiments in Fluids 41: p 933-947

Tomography describes the reconstruction of the particle locations that are stored as grey scale image projections captured by the four different cameras. Each particle is identified, and using a line-of-sight algorithm (MART) a particle’s position can be retrieved. Other algorithms that increase data yield (MTE) and that reduce computational time and memory storage (MLOS-SMART, MFG) exist that can be implemented.

Once the particles’ 3D positions are known, there are several steps to resolve the velocity vectors. Two salient methods being the 3D cross-correlation and the relaxation method that retrieve a particle’s movement between time-steps. Dividing the displacement by the time between laser pulses gives us a volumetric velocity field with the ability to greatly increase our understanding of complex flows.

The goals of our research are to develop and make improvements to the algorithms of Tomographic PIV and to measure complex 3D flows. Improvements will save processing time and increase data yield whilst the measurements will be able to further our understanding of their complex structures. To test the performance of the algorithm, it will be applied to lifelike synthetic flows; this verification will give confidence to its analysis on subsequent experimental data.

Learning & Teaching

  • CIVL3612 Fluid Mechanics II
  • CIVL3613 Coastal Engineering
  • CIVL2511 Instrumentation and Measurement