the proper and quantitative recognition of the scale of turbulence in regard to issues such as sediment transport is of major importance. different experimental techniques can be used to determining the scale of turbulence, but the accuracy of these techniques is open to question. in this paper, after a review of the taylor method, the restrictions and advantages of velocity measurement techniq...

This paper describes features in the structure of a laminar vortex ring ejected vertically from an elevated pipe into a uniform horizontal cross flow. Measurements are obtained by particleimage velocimetry (PIV) and flow-visualisation images are obtained by planar-laser-induced fluorescence (PLIF). Cross flow produces a shear layer over the open end of the elevated pipe. As a vortex ring is eje...

We propose a point measurement technique for simultaneous gas temperature and velocity measurement based on thermographic phosphor particles dispersed in the fluid. The flow velocity is determined from the frequency of light scattered by BaMgAl10O17:Eu2+ phosphor particles traversing the fringes like in conventional laser Doppler velocimetry. Flow temperatures are derived using a two-color rati...

In order to increase containment efficiency and reduce energy consumption, an inclined quad-vortex range hood (IQV range hood) was developed and tested by experimental methods. The flow structure was observed by a laser-assisted flow visualization technique and laser Doppler velocimetry (LDV). Leakage characteristics were measured by the tracer gas (sulfur hexafluoride) detection method. By arr...

This paper examines various techniques that have been developed to measure flow fields in microfluidic devices with 10 – 10 micron-scale spatial resolution. These techniques include Scalar Image Velocimetry (SIV), Laser Doppler Velocimetry (LDV), and Particle Image Velocimetry (PIV). Advantages and disadvantages of these techniques are presented. PIV results are presented for a liquid flow thro...

Bidirectional laser Doppler velocimetry (LDV) and fundus photography were applied to investigate the effects of light and darkness on retinal blood flow. Blood flow had increased by an average of 67% after 5 min of darkness. This increase persisted for periods of darkness as long as 80 min (the longest period tested). The magnitude of this elevation, its time course, and its neutralization by t...