Marine Skin Friction and Turbulence Measurements Using Doppler Optical Coherence Tomography

Physical Sciences Inc. (PSI) proposes to develop and demonstrate a novel, non-obtrusive system based on a Fourier Domain Doppler Coherent Optical Tomography (FD-DOCT) technique to measure the near-wall fluid velocity profile, skin friction and turbulence characteristics present in high Reynolds number fluid flow. This system will allow fluid velocity profile measurement with high spatial resolution (5 microns) in the 5 to 100 micron region of the wall/fluid boundary and thus provide direct information on wall shear stress, a quantity of paramount interest to researchers in their efforts to understand turbulent flow and its contribution to drag resistance for submarines and ships. The spatial resolution of this technique, combined with its speed of measurement and ability to function in highly turbulent flows, will exceed those of the traditional techniques for flow field measurements such as Hot Wire Anemometry, LDV and PIV, and for shear stress measurements using direct or inferred schemes. This improved accuracy will translate into a better understanding of Reynolds number scaling, improved CFD validation, and submarine/ship configuration design. We have already performed proof-of-principle experiments that demonstrated the ability of FD-DOCT to make fluid flow measurements in a water flow environment.