Coherent Dynamics and Energetics in Thin Flat Plate Wakes
The dynamics and energetics of two mean two-dimensional wakes behind a flow-normal thin flat plate, induced by inclusion and exclusion of end plates, are studied. Both wakes are characterized by quasi-periodic vortex shedding but differ in mean topology and typical wake characteristics, such as mean base pressure and recirculation length. Energetically optimal proper orthogonal decomposition modes are used to approximate the coherent motion and thus triply decompose the velocity field into a mean, coherent, and residual field. This is utilized to obtain a dynamic characterization of the wakes and to study the large scale coherent structures and their energetic exchanges with other scales of motion. From this, a slow-varying base flow and lateral shear layer flapping are shown to influence the shedding dynamics differently in each wake. These differences in the mean field and coherent dynamics are related to wake turbulence levels and vortex deformation, and thus are at the beginning of the energy cascade and the energy transfer process related to the wake turbulence levels.
Fluid Dynamics, Fluid Mechanics, Turbulence, Bluff-body Wakes, Low-order Modeling, Vortex Shedding, Low-frequency Wake Dynamics
Agrey, K. (2021). Coherent dynamics and energetics in thin flat plate wakes (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.