Evanescent wave doppler velocimetry for fluid flow in a wall's near field

This study deals with the evanescent wave Doppler velocimetry, which has been proposed by one of the authors for measuring flow velocity in a wall's near field. In order to evaluate the applicability of the velocimetry to a viscous flow, the velocity measurement in a Couette flow of water between a gap of 1.5mm, which is considered to have a linear velocity distribution, has been performed. Although the measured velocities are slightly smaller than the corresponding ones that are predicted assuming the linear velocity distribution, the applicability of the velocimetry to a viscous flow has been evaluated. This study also shows tracer particles that are suitable for the velocimetry.