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Type of Document	Dissertation
Author	Lang, Daniel Bernard
URN	etd-08312005-112325
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-08312005-112325
Title	Laser Doppler velocity and vorticity measurements in turbulent shear layers
Degree	PhD
Option	Applied Physics
Advisory Committee	Advisor Name Title Paul E. Dimotakis Committee Chair
Keywords	none
Date of Defense	1984-11-12
Availability	unrestricted
Abstract NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. A Laser Doppler Velocimeter (LDV) system was developed to measure the instantaneous spanwise vorticity, [...], in a turbulent shear layer. It was necessary to design and fabricate the LDV optics and processing electronics, as no commercially available LDV systems met the specifications of measuring the velocity at four closely spaced points to the requisite accuracy. Measurements were also made of the instantaneous u, v, u’, v’, and - u’v’. The instantaneous vorticity was processed to obtain an estimate of its probability density function, from which the mean and rms values were estimated. It was also possible to separate the irrotational fraction of the flow ([...]) from the rotational (intermittent) fraction of the flow ([...]). The development of the intermittency profiles, based on vorticity, as a function of the downstream distance from the splitter plate was studied. A notable feature is that the vorticity is found to have values opposite the mean sense of rotation, i.e., [...], a significant fraction of the time. Additionally, a detailed study was performed to evaluate the approximation of [...], in terms of various local temporal derivatives [...]. The optimum choice for u(y) can be found and is influenced by the relative local convection velocities of the small and large scale structures.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    Lang_db_1985.pdf 4.79 Mb 00:22:11 00:11:24 00:09:59 00:04:59 00:00:25