Scalar dispersion in a smooth wall turbulent boundary layer from a point source at the wall

We present an experimental investigation on the dispersion of a passive scalar, released from a point source at the wall in a turbulent boundary layer naturally developing in a water tunnel. Simultaneous measurements of concentration and velocity fields are carried out by combining two planar techniques: quantitative planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV) on a domain over a field of view of 3.5δ x 1.2δ (where δ is the boundary layer thickness), immediately downstream of the point source. These measurements provide physical insight into the scalar transport processes allowing for the assessment of the scalar fluxes u’c’ and v’c’, together with the momentum fluxes, which are critical parameters for dispersion models applied to weather modelling, pollution transport, and industrial mixing processes.