LIF measurement of turbulent horizontal dense jets in stagnant ambient

This study investigates the behavior of turbulent horizontal dense jets (THDJs) under varying bottom confinement scenarios using laser-induced fluorescence (LIF) techniques. The experiments aim to extend the current understanding of both mean and turbulent characteristics of these jets as they propagate streamwise up to 75 nozzle diameters ($75D$) from the nozzle exit. The selected scenarios avoid typical wall jet and Coanda effects, focusing instead on medium and low bottom confinements. A comprehensive study on the concentration fluctuation field was carried out along and across the trajectories for multiple sections. Proper orthogonal decomposition (POD) analysis reveals that buoyancy-induced instabilities in the lower layer impede the formation of helical or axisymmetric structures. It turns out that contribution of turbulence in the most confined case ($H/D=3$) was more than the rest of the scenarios.