Author(s): Qian Liao; Harvey A. Bootsma

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Abstract: Small-scale hydrodynamics in environmental fluid flows, i.e., in rivers, lakes, oceans and wetlands, is an important factor that controls and limits many environmental transport processes, especially those near a physical interface such as the water-sediment interface, air-water interface, and water-vegetation interface. Traditional turbulent velocity measurements in field studies are usually limited to one point or along a line in space, and they lack the resolution to characterize the turbulence at dissipative scales. We have developed a self-contained Underwater Miniature Particle Image Velocimetry (UWMPIV) system to facilitate research on small-scale turbulence in the vicinity of environmental interfaces. The UWMPIV employs a compact continuous-wave (CW) laser and an optical scanner to deliver a light sheet that illuminates naturally occurring particles. Particle images are taken by a CCD camera along with an ultracompact PC. The non-tethered and compact design fits in two small underwater housings with all components powered by batteries: an ideal design for a variety of in situ deployments. The system has been field-tested in several freshwater lakes and rivers. A sample result is presented which shows in situ PIV measurements of turbulent mixing induced by internal waves on a sloping bottom of Lake Mendota (Madison, WI, USA).

DOI:

Year: 2009