Measurement of fluid velocity gradients using laser-doppler techniques

Two methods are developed for the measurement of fluid velocity gradients using a laser-Doppler anemometer. In the first method the velocity gradient is found by a single measurement of the bandwidth of the laser-Doppler signal spectrum. In the second, velocity gradients very close to a wall are calculated from the amount the signal spectrum shifts in frequency for a small change in the position at which the spectrum is measured. Both methods are examined theoretically and experimentally.