

Article
Direct numerical simulation of a plane turbulent walljet including scalar mixing
AbstractDirect numerical simulation is used to study a turbulent plane walljet including the mixing of a passive scalar. The Reynolds and Mach numbers at the inlet are Re=2000 and M=0.5, respectively, and a constant coflow of 10\% of the inlet jet velocity is used. The passive scalar is added at the inlet enabling an investigation of the walljet mixing. The selfsimilarity of the inner and outer shear layers are studied by applying inner and outer scaling. The characteristics of the walljet are compared to what is reported for other canonical shear flows. In the inner part, the walljet is found to closely resemble a zero pressure gradient boundary layer, and the outer layer is found to resemble a free plane jet. The downstream growth rate of the scalar is approximately equal to that of the streamwise velocity in terms of the growth rate of the halfwidths. The scalar fluxes in the streamwise and wallnormal direction are found to be of comparable magnitude. The scalar mixing situation is further studied by evaluating the scalar dissipation rate and the mechanical to mixing time scale ratio.

