Date of this Version
Spaulding, E. 2019. Studies of Boundary Layer Transition from Laminar to Turbulent.Undergraduate Honors Thesis. University of Nebraska-Lincoln.
In engineering applications, there is a strong desire to reduce energy losses due to turbulent energy production. However, the theoretical understanding of turbulent and transition flow is still lacking due to the absence of an exact mathematical solution for turbulent flow. In the current project, transition and turbulent behavior in wall-bounded flow is studied, with an emphasis on concepts from boundary layer theory. Organized structures, such as streaks, waves, and vortices, which occur in such flows, are analyzed. Especially for near-wall structures, control strategies for suppressing such structures are discussed. Using mathematical equations which govern fluid flow, models for different behaviors are derived, studied, and simulated computationally. Peer-reviewed literature covering these topics is given a careful review and is used as a point of comparison for the results of the current study. Fundamentals of the structure of the boundary layer are given, noting flow separation's role in producing wake turbulence. Simulations of turbulent channel flow were run at varying conditions with the goal of studying how changing properties of flow at the wall affects transition and turbulence. Results of the current study include analysis of mean velocity and wall shear stress profiles, analysis of flow structures, and observations of the dependence of the Reynolds number on the time for transition from laminar to turbulent flow.