Advanced modeling of flows with turbulence, multiple phases and complex surfaces

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Many industrial and environmental flows of interest to engineers are turbulent and multiphase, and involve a solid boundary. A turbulent flow is characterized by apparently random fluctuations in the local velocity field due to eddy motions of different size and orientation. Turbulent flows are of great practical importance, since they are characterized by intense mixing and high transport rates. One important multiphase flow is the flow of a fluid containing solid particles. In this case, the particle transport is dominated by the hydrodynamic drag forces on the particles. The proposed research program will investigate the characteristics of turbulent and multiphase flows, with a focus on the fluid interaction with the solid surfaces. It will also study non-turbulent, micro-fluidic flows over complex walls associated with living tissues. Four different wall flow configurations will be studied. The first flow configuration is a turbulent plane wall jet, created by directing a jet parallel to a wall. For walls with a rough surface, the effect of the roughness on the jet is not yet fully understood. The second flow configuration is flow over a finite prism mounted on a ground plane. The wake created behind the prism is complex and contains unsteady vortical structures. The exact mechanism for the generation of these structures has not yet been determined. The third flow configuration is that of turbulent gas-particle flow, such as occurs in pneumatic transport. In this case, the interaction between the particles and the turbulence is complex and difficult to incorporate in engineering models. The final configuration is micro-fluidic flow through a porous tissue scaffold which facilitates the growth of biological tissue. The tissue surface grows and changes in response to the nutrients and mechanical stimulation supplied by the flow. The study of these flow paradigms will provide new insight as to how a fluid interacts with solid walls of different configurations. The flows will be studied using novel numerical and experimental methods to obtain the instantaneous velocity fields, which will be processed using advanced analysis tools to identify the pertinent flow structures. These studies will not only advance our fundamental understanding of fluid-solid interactions, but will also be used to improve the turbulence and multiphase models used by engineers to predict mean flow properties in industrial and environmental applications. Finally, the ability to simulate flow over a living tissue, which grows and changes in response to the flow characteristics, will demonstrate the potential of computational fluid dynamics to enhance our understanding of biomedical systems.