Seminar - Steve Cochard - New trends in Particle Image Velocimetry PIV
Wednesday 25 August 2010, 4.30 pm - 5.30 pm
Civil Engineering Lecture Theatre 1
Dr Steve Cochard
School of Civil Engineering
University of Sydney
Abstract:
This talk will focus on the fundamentals of PIV before exploring the latest trends in 3D-PIV.
PIV
PIV is a non-penetrative technique of extracting the two components of the velocity from a desired planar flow region [1]. A laser pulse lights a plane section of the flow and highlights particle tracers while a camera records their position. A second laser pulse illuminates, a short time later (~100 ms), the same section of the flow. Two components of the velocity fields can be retrieved from the position difference of the particles in the plan of the laser sheet. To measure the three components of the velocity, two cameras take images of the laser sheet from different angles. The two images combined together give the three components of the velocity [2], [3].
[1] David, L. & Gicquel, P. (2006). “Evolutions de la technique PIV à travers quelques conférences internationales de 2000 à aujourd'hui”, Proc. Congrès Francophone de Techniques Laser, CFTL 2006, Toulouse, 19 - 22 septembre 2006.
[2] Felli, M., Pereira, F., Calcagno, G., & Felice, F. D. (2002). “Application of Stereo-PIV: Propeller Wake Analysis in a Large Circulating Water Channel.”. Proc. 11th Int. Symp. on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal
[3] Prasad, A. K. (2000). “Stereoscopic particle image velocimetry.” Experiments in Fluids 29, 103–116.
Speaker Details
Since graduating, Steve has been involved on both numerical and experimental projects. He particularly enjoys developing new measurement techniques.
Steve has just joined the Fluid and Environmental Group at the School of Civil Engineering after holding a Postdoc position in the Complex Fluids Laboratory at the University of British Columbia. His research has focused on the design, the development and the validation of a PIV system to provide an accurate measurement of the velocity field inside transient free-surface flow of viscoplastic materials.
His Ph.D. thesis entitled `Measurements of Time-Dependent free-surface Viscoplastic flows Down Steep Slopes' was completed under the supervision of Pr. C. Ancey at the Environmental Hydraulic Laboratory at EPFL. A novel fringe projection system was developed to provide accurate instantaneous whole-field 3D shape measurements of the free-surface profile and the spreading rate of non-Newtonian fluids at high repetition rate.
Before joining the Environmental Hydraulic Laboratory Steve had been working for more than four years in industry as an aero-thermodynamics engineer. There he had been associated with multidisciplinary projects with state-of-the art technology and competences. At first he joined for one year the Research and Technology Department of SNCF (Société Nationale des Chemins de Fer, French National Railway Company) in Paris, France as an internship for my master thesis and then as a consultant on the implementation of solutions to problems related to the complex and hazardous side-wind effect of the new TGV line Paris-Marseille. Some of the key duties were the implementation of a network of weather stations, the development of new algorithms to post-treat wind data and to detect and predict in real time the apparition of dangerous wind conditions that are used to adapt the kinematics of trains to avoid accidents. Later, he joined the Tunnel Ventilation Group at Electrowatt Infra AG in Zürich as a Project Engineer, where he was a project leader for the development and improvement of ventilation systems on several existing tunnels or tunnel projects in particular in case of accidents leading to hazardous situations for people caught inside the tunnels. He was in charge of the development of numerical tools to simulate smoke, toxic gases and temperature propagation in case of fire in any underground facility with different ventilation configurations and he additionally supervised all the wind-tunnel tests realized for the new Bangkok metro line.