Particle Image Velocimetry (Velocimetry == measuring velocity in fluids) is an experimental technique for measuring the velocity field in a fluid flow. Neutrally-buoyant tracer particles (i.e., research-grade glitter) are seeded into the flow. Particles are illuminated using a laser with the beam expanded into a plane of light.
Images of the tracer particles are split into a grid of overlapping windows. Cross-correlation between corresponding windows at successive times determines their displacement, which in turn can be used to determine velocity.
Prof. Mendelson has also worked extensively on three-dimensional PIV techniques, which use multiple camera viewpoints and volume illumination to construct 3D particle fields.
Most experiments in the Flow Imaging Lab take place in our 75 gallon testing tank.
Flow measurements are also supported by the following resources:
Edgertronic SC1 high speed camera
Chronos 2.1 high speed camera
Flir Blackfly 3D camera array
5W and 3W 532 nm (green) continuous wave lasers
June 2025: "Fish Out of Water" The Academic Minute https://academicminute.org/leah-mendelson-harvey-mudd-college-fish-out-of-water/
October 2017: "Biomimicking the Archer Fish" ASME.org. https://www.asme.org/engineering-topics/articles/manufacturing-design/biomimicking-the-archer-fish
June 2017: "Fish Flight" MIT Technology Review. https://www.technologyreview.com/s/608007/fish-flight/
April 2017: "The archer fish may be paving the way for underwater vehicles" earth.com. https://www.earth.com/news/archer-fish-underwater-vehicles/
April 2017: "High-speed images capture archer fish's rocket-like launch" MIT News. http://news.mit.edu/2017/high-speed-images-capture-archer-fish-launch-0419