Fluid Mechanics Research

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The specific objectives of the proposed work are: a) to investigate multi-structure turbulence, to document the scaling of energy dissipation and to scrutinize the validity of fundamental assumptions in turbulence theory; b) to study the interaction between anisotropic, sheared turbulence in the free stream and turbulence generated by a stationary or moving wall; c) to document the turbulence structure, by-pass transition and relaminarisation, scalar transport from concentrated sources, heat transfer from the wall and vortex shedding from internal objects in temporally accelerating and decelerating channel flows; d) to extend Taylorian turbulent diffusion theory to developing and multi-structure flows, to devise conditions that optimize scalar diffusion and mixing and to investigate the effect of Schmidt/Prandtl number on the scalar fine structure and the development of differential diffusion; e) to study experimentally vortex stability and breakdown under the influence of transverse and streamwise disturbances, and to document in detail the mutual interactions between a streamwise vortex and coherent structures in a turbulent free stream; f) to modify an existing mock circulation loop so that it reproduces physiological coronary flows and to collect velocity measurements in an anatomical model of the aorta near the coronary inlet for different orientations of a prosthetic heart valve. ***Results of these research projects are expected to contribute to basic scientific knowledge in several areas of the field of fluid mechanics. Our systematic scrutiny of cornerstone assumptions in turbulence theory has the potential for a significant advance in the understanding and modelling of turbulent flows. Our measurements in many unique configurations will likely continue being benchmarks for the validation of turbulence models and CFD analyses; for example, the study of flows near moving walls would be quite relevant to the analysis of flows in turbomachinery. The study of accelerating and decelerating channel flows also has a wide range of industrial, environmental and biological applications. The work on turbulent diffusion will further contribute to our understanding and modelling capabilities of the spreading and mixing of scalar admixtures, with implications for the dispersion of pollutants and the efficiency of combustion and other chemical reactions. Our work on wing-tip vortices is important to aviation economy and safety. Finally, the work on coronary flows may assist surgeons in optimizing implantation of valves and generally help fight cardiac disease. In summary, like those of my previous work over more than four decades, the results of the proposed research should benefit the power generation, environmental, aerospace, transportation, biomedical and health services sectors of the economy, both in Canada and worldwide.