Point source dispersion in a direct numerical simulation of turbulent channel flow

The dispersion of a scalar quantity from point sources located in a Direct Numerical Simulation of turbulent channel flow is studied. An algorithm for tracking fluid particles or molecular (or thermal) markers is developed and tested. Accurate estimates of a number of Lagrangian characteristics of the flow, necessary for the description of the diffusion process, are reported for the case of a point source in the center of the channel. The consequences of molecular diffusivity on the effectiveness of the turbulence to disperse a foreign substance (or heat) are also explored. A new method is proposed for calculating the effect of Peclet number on the Lagrangian property autocorrelation in isotropic turbulence. Computed property autocorrelations, from a simulated experiment of point source diffusion in the center of the channel, are also reported. Finally, results for the diffusion from point sources located at the channel walls are presented and discussed.U of I OnlyETDs are only available to UIUC Users without author permissio