Controlling the development of the turbulent three-dimensional wall jet

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Turbulence research is of the greatest practical importance; Holmes et al. (2002) suggested that ''turbulence is responsible for the vast majority of human energy consumption, in aircraft fuel, pipeline pumping charges, and so forth." However, despite its widespread relevance, the equation set describing turbulent flows is not closed and the prediction of phenomena associated with turbulence, such as drag and heat transfer, remains difficult. Computational Fluid Dynamics (CFD) is a commonly used tool for predicting the behaviour of turbulent flows. Unfortunately, the majority of the codes have been formulated for two-dimensional mean flows and often yield unsatisfactory results in flows with even mild three-dimensionality. This is often due to inability of most models to accurately account for the generation of secondary flow due to the directional nature of the turbulence. For example, the turbulent three-dimensional wall jet is a flow that is characterized by strong secondary flows and consequently, conventional turbulence models are unable to predict the growth of three-dimensional wall jets to within 50%. This is particularly problematic given the frequent occurrence of three-dimensional wall jets in engineering problems (i.e. Heating Ventilation Air Conditioning (HVAC) systems, effluent discharge, film cooling, airfoil design, electronics cooling, combustion applications and cooling the outer surfaces of high speed re-entry vehicles and rockets). The present research examines the turbulence in the three dimensional wall jet in the hopes of improving our understanding of turbulence generated secondary flow and its relationship to the organized vortical motions in the flow.