High Spatial Resolution Measurement of Turbulent Channel Flow Using 2C-2D PIV and 3C-3D Digital Holographic PIV

Experimental measurements of turbulent channel flow have historically lagged behind direct numerical simulations (DNS). However, they remain essential for verifying simulations that involve surface treatments, such as micro-texturing of the channel walls. This presentation reports on high-resolution measurements of turbulent channel flow using 2-component – 2-dimensional (2C-2D) particle image velocimetry (PIV) and 3-component – 3-dimensional (3C-3D) Digital Holographic PIV (DHPIV).

The measurements were conducted in a water channel with a test section 20 mm high and 700 mm wide, yielding an aspect ratio of 35, which ensures that the mean flow at the channel centerline is nominally two-dimensional. The frictional Reynolds number (Re_τ) is 1400. Using a pair of 100 MP sensors, the spatial resolution of the 2C-2D PIV is less than the viscous length scale. For the 3C-3D DHPIV, the presented methodology applied a three-dimensional volume deconvolution to mitigate the depth-of-focus and virtual image issues, and a predictive inverse reconstruction approach was used to improve the dynamic range of particle reconstruction.