Particle Image Velocimetry

Particle Image Velocimetry (PIV) is widely acknowledged as the leading flow measurement technique in experimental fluid mechanics. Its working principle is based on the indirect evaluation of the flow velocity by measuring the displacement of small particles inserted into the flow and carried by the fluid. These tracer particles are illuminated by a light source, typically a laser, and their position is recorded by digital cameras.

The introduction of digital PIV in the early 1990s has greatly contributed to enhance the understanding of turbulent and complex flows. Recent advances of the technique include the possibility of measuring the flow field in three-dimensional volumes, which can be efficiently achieved in particular by tracking the position of individual tracer particles in successive time instants (Lagrangian Particle Tracking, LPT). The availability of the velocity and acceleration of fluid elements in a three-dimensional domain also enables the determination of flow pressure and aerodynamic loads (using e.g. data assimilation methods), which is highly relevant for the design of new aerodynamic systems.

Example of large-scale PIV measurement around a full-scale cyclist model (Jux et al., 2018)

Instantaneous 3D LPT result of an impinging jet, showing dense trajectories of tracer particles (left), vortical structures from regularized interpolation (middle) and a slice of the 3D pressure field (right) (Huhn et. al. 2018).

The SIG 32 “Particle Image Velocimetry” focuses on the developments and applications of particle-image based flow measurement techniques intended in broad sense, including both the conventional cross-correlation based approach (PIV) and Lagrangian Particle Tracking. The SIG 32 aims at bringing together researchers and users of PIV and LPT to:

1. Promote the use of PIV and LPT for both fundamental research and industrial applications
2. Widen the range of applicability of the technique while reducing the complexity of the experimental setup (lower user’s expertise required)
3. Define standard approaches and best practices for PIV and LPT data acquisition and processing.

The activities of the SIG 32 will involve workshops on specific aspects of PIV and LPT as well as a wide range of applications. Additionally, challenges will be organized where the participants will compete to define the best approaches for image evaluation and data processing. Examples of the workshops topics include:

PIV Movies