On the An-isotropic Turbulent Wake Flows Near Unsteady Free Surfaces

Turbulent wake flows of surface-piercing body near unsteady free surfaces critically affect a wide range of engineering applications. This study presents experimental investigations of anisotropic turbulent wake flows within a three-dimensional volume. A two-dimensional slender surface-piercing wedge with a width-to-length ratio of 1:7 was employed to generate wake flows across a range of Reynolds and Froude numbers. In addition to qualitative fluorescent dye visualization, the state-of-the-art flow diagnostic techniques, including time-resolved planar Particle Image Velocimetry (PIV) and volumetric defocusing PIV, were employed to characterize the spatio-temporal an-isotropic dynamics of the wake flows. The presented results depict the strong Froude number dependency of the near-surface wake flow, resulting in reduced coherency and extended re-circulation zone. At high Froude number, the turbulent fluctuations and Reynolds shear stress are suppressed near the free surface, indicating stabilized wake flow. The underlying flow of physics of the presented results is discussed.