3-D (Three Dimensional) Particle Imagery Velocimetry (PIV)

Description:

To visualize the flow distributions the laboratory uses a non-invasive measurement technique called PIV.  This involves microscopically small, highly reflective particles are added to the flow to aid in analysis. Then a laser illuminates a thin layer of the flow so that only the particles in that light sheet reflect the laser's light. With 3-D PIV two cameras are pointed with different angles toward the light sheet. As in 2-D PIV, two succeeding images and an algorithm based on statistical probability are used to determine the speed and the direction of the moving particles for two dimensions for each camera. These both velocity information and some trigonometrically functions allows us to determine the velocity in 3-D space for the light sheet cross section.

Experimental Setup for 3-D PIV

We are using the 2-D PIV technique to visualize cross sections of a bridge deck, which is submerged by water to determine the effective flow depth.

Superimposed image: This illustrates where the water moves the fastest and in what direction.