Side-projected fiber-optic velocity sensors

Side-projected dual-fiber velocity sensors with various fiber core separations for in vivo measurements were developed and tested. Good linearity between the flow velocity and the Doppler shift frequency is obtained with this sensor in both the forward (toward the sensor tip) and reverse (away from the sensor tip) flow directions. Experimental and numerical analysis of the data showed that the boundary layer along the side wall of the fiber sensor varies with the flow velocity.