An apparatus is described by means of which the power versus frequency spectrum of the photomultiplier current can be obtained for laser light scattered by streaming cytoplasm in the algal cell Chara corallina. A Doppler peak is noted in the spectrum which is abolished when cytoplasmic streaming is arrested by electrical stimulation. For 5 cells of Chara, this simple laser-Doppler velocimeter g...

An experimental study of Taylor’s hypothesis in a quasi-two-dimensional turbulent soap film is presented. A two probe laser Doppler velocimeter enables a non-intrusive simultaneous measurement of the velocity at spatially separated points. The breakdown of Taylor’s hypothesis is quantified using the cross correlation between two points displaced in both space and time; correlation is better tha...

An experimental study of Taylor’s hypothesis in a quasi-two-dimensional turbulent soap film is presented. A two-probe laser Doppler velocimeter enables a nonintrusive simultaneous measurement of the velocity at spatially separated points. Using the cross correlation between a pair of points displaced in both space and time, the velocity coherence is measured to be better than 90% for scales les...

Copyright© 2001 by Gharib, Modarress, Fourguette, and Wilson. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Abstract This manuscript describes two MEMS based optical sensors for wall shear stress and velocity measurements in flow fields. Experimental results obtained with the wall shear stress sensor, the MicroS3, are compared with boundary layer ve...