An Investigation of the Turbulent Structure in Two-Dimensional Momentumless Wakes

Flow visualization, hot-wire anemometry and laser-doppler velocimetry (LDV) are used in a low-turbulence wind tunnel to study experimentally the flow downstream of a two-dimensional "momentumless" body. This flow is characteristic of the wakes of self-propelled bodies (such as aircraft or torpedoes) moving at constant velocity. The unique property of this flow field which distinguishes it from jets, wakes, and mixing layers is the very rapid decay of turbulent structures due to lack of production of turbulent energy downstream of the body. Smoke-wire flow visualization techniques will be employed to qualitatively identify the geometry and scale of turbulent structures produced at the body. In addition, the streamwise decay of these structures will be studied by moving the smoke-wire assembly downstream. Three-dimensional aspects of the flow will be studied as well. Hot-wire and LDV measurements will be used to obtain quantitative descriptions of the flow field, such as Reynold's stresses, velocity fluctuation frequencies, and energy spectra.