The first-passage properties of a passive tracer in three-dimensional multipole flows.
Item
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Title
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The first-passage properties of a passive tracer in three-dimensional multipole flows.
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Identifier
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AAI9720159
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identifier
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9720159
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Creator
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Zhang, Ming.
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Contributor
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Adviser: Joel Koplik
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Date
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1997
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Fluid and Plasma | Physics, Condensed Matter
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Abstract
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We study the hydrodynamic dispersion of a passive tracer in three dimensional flows between sources and sinks in porous media. The practical motivation is to understand how measurements of the first passage transit time distribution of a passive tracer reflect the geometry and inhomogeneity of oil and water reservoirs. The more general motivation is to extend the one and two dimensional phenomenology of solutions of the convection-diffusion equation to realistic situations. We explore the properties of the transit time probability distribution for the tracer transport in homogeneous and heterogeneous medium with a variety of multipole flow geometries. For tracer motion in a statistically homogeneous medium, we systematically study the behavior of the first-passage probability, p(t), by the analytical and numerical methods for pure convection and numerically for the general combination of diffusion and convection in multipole flows. The results show that the generic features of the transit time probability p(t) consist of a power-law decay region, an exponential region, and a diffusive shoulder, whose parameters may be correlated with the geometry of the flow domain and the Peclet number. To consider the effects of heterogeneity, we consider the effects of localized random perturbations to multipole flows. The full numerical studies indicate that the effects of local perturbation lead to the bending of flow geometry and produce some fluctuations which increase with the strength of the perturbations in whole region of the transit time probability distribution at high Peclet number, and make some shifts for first-time probability in whole decay regions at low Peclet number. We investigate the effects of barrier to flow as another example of a heterogeneous system. The studies of the barrier problem indicate that the barrier distorts the global flow geometry and changes the exponent of the power-law decay at high Peclet number, and enhance the diffusivity in flow at low Peclet number.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
