Second-order model of entrainment in planar turbulent jets at low Reynolds number

Turbulent jets and plumes are commonly encountered in natural and industrial environments, and have been the objects of seminal works on turbulent free shear flows. The dynamics of turbulent jets is most often described as a function of the so-called entrainment coefficient, α, which quantifies the entrainment of ambient fluid into the jets. This key parameter has been determined in numerous and extensive experimental, numerical, and theoretical studies of axisymmetric jets. However, data remain scarce on turbulent planar jets. Available studies have shown that at low distance from the source, α increases with the source Reynolds number, and that α increases with distance from the source for large source Reynolds number. But no link has been made between these two kinds of observation so far. To study the relative influence of source Reynolds number, Re0, and distance from source on entrainment in planar turbulent jets, we perform new experiments at low Re0 (between 59 and 424) with three different aspect...