Snohomish River (Wash.) -- Streamflow -- Measurement, Snohomish River (Wash.) -- Turbulence, Snohomish River (Wash.) -- Remote sensing
Thermal infrared (IR) based particle image velocimetry (PIV) is used to measure the evolution of velocity, turbulent kinetic energy (TKE), and the TKE dissipation rate at the water surface in the tidally influenced Snohomish River. Patterns of temperature variability in the IR imagery arise from disruption of the cool skin layer and are used to estimate the 2D velocity field. Comparisons of IR based PIV mean velocity made against a collocated acoustic velocimeter demonstrate high correlation (r2 > 0.9). Over a tidal period, surface TKE computed from the IR velocity varies from 10-4 J·kg-1 to 3x10-3 J·kg-1, with an average difference from the in situ measurements of 8%. IR-derived TKE dissipation rates vary from approximately 3x10-6 W·kg-1 to 2x10-4 W·kg-1 at peak ebb, agreeing on average to within 7% of the in situ velocimeter results. Infrared-based PIV provides detailed measurements of previously inaccessible surface flow and turbulence statistics.
Chickadel, C. Chris; Talke, Stefan A.; Horner-Devine, Alexander R.; and Jessup, Andrew T., "Infrared-Based Measurements of Velocity, Turbulent Kinetic Energy, and Dissipation at the Water Surface in a Tidal River" (2011). Civil and Environmental Engineering Faculty Publications and Presentations. 83.