A PRELIMINARY EVALUATION OF RANDOM-FORCING TECHNIQUES FOR SCALAR DISPERSION SIMULATIONS IN SPATIALLY-DEVELOPING FLOWS

We present a preliminary evaluation of random-forcing techniques for generating fully-developed turbulence upstream of a scalar source. Using this method, the incoming laminar flow is simply perturbed using a time-dependent momentum source consisting of superimposed harmonic modes with randomly distributed coefficients (white-noise signal). The forcing technique has been employed for DNS of scalar dispersion from a line source downstream of a square obstacle using unstructured finitevolume schemes. This flow configuration was found particularly sensitive to inflow conditions because of the breakdown in the shear-layer originating from the leading edge of the obstacle. The results obtained after an initial tuning of the forcing-amplitude parameter are encouraging, but further studies are needed in order to establish the predictive capabilities of this method.