通过对流动起伏的时域和空域分析获测量流动速度和流动方

If exposed to bulk water flow, fish lateral line afferents respond only to flow fluctuations (AC) and not to the steady (DC) component of the
flow. Consequently, a single lateral line afferent can encode neither bulk flow direction nor velocity. It is possible, however, for a fish to
obtain bulk flow information using multiple afferents that respond only to flow fluctuations. We show by means of particle image
velocimetry that, if a flow contains fluctuations, these fluctuations propagate with the flow.Across-correlation of water motion measured
at an upstream point with that at a downstream point can then provide information about flow velocity and flow direction. In this study,
we recorded from pairs of primary lateral line afferents while a fish was exposed to either bulk water flow, or to the water motion caused
by a moving object.Weconfirm that lateral line afferents responded to the flow fluctuations and not to theDCcomponent of the flow, and
that responses of many fiber pairs were highly correlated, if they were time-shifted to correct for gross flow velocity and gross flow
direction. To prove that a cross-correlation mechanism can be used to retrieve the information about gross flow velocity and direction, we
measured the flow-induced bending motions of two flexible micropillars separated in a downstream direction. A cross-correlation of the
bending motions of these micropillars did indeed produce an accurate estimate of the velocity vector along the direction of the
micropillars. 德国LaVision PIV/PLIF粒子成像测速场仪 HighSpeedStar PIV相机 用于粒子成像测速(PIV)的荧光示踪粒子