Combined Planar Measurements of Flow Velocity and Mass Concentration in Shallow Turbulent Flow Part 1: Development of a Planar Concentration Analysis (PCA) System

For the experimental investigation of the transfer of mass concentrations in shallow turbulent flows an time/cost efficient and easy-to-use measuring technique will be presented. The Planar Concentration Analysis (PCA) technique allows to evaluate the depth-averaged concentra- tion of a soluble conservative tracer, namely food coloring. Since PCA is based on video image analysis, the spatial and temporal resolution is high, depending on the optical components and on the digitalisation and storage capacity. Details will be given to the algorithm for the conversion of light intensity to concentration , which also accounts for the non-linear relation. This extension significantly increases the measurement range for mass concentrations. Finally the PCA system will be applied to the spreading of a tracer plume for a continuous point- source in a shallow turbulent laterally unbounded flow.