Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 31 for “"eddy diffusivity"”.
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Improving parameterization of scalar transport through vegetation in a coupled ecosystem-atmosphere model
… scalar transport using a rough-wall boundary eddy diffusivity formulation. This formulation predicts unreasonably high soil evaporation beneath tall, dense forests and low soil evaporation beneath short, sparse grass. This study investigates alternative formulations by reviewing literature on …
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Droplet Dispersion in a Turbulent Pipe Flow (Particle, Two-Phase, Diffusion)
… pipe flow of air has been investigated. The eddy diffusivity, (epsilon)(,p), mean-square fluctuating velocity, v(,p)('2), and Lagrangian integral time scale, (tau)(,p), of droplets with diameters of 50, 90, and 150 (mu)m are estimated. The centerline mean air flow velocity varied from 400 to …
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Physical controls on copepod aggregations in the Gulf of Maine
… The summertime mean surface circulation and eddy kinetic energy are computed from a Lagrangian drifter dataset and an adaptive technique that allows for higher spatial resolution while also keeping uncertainty low. Eddy diffusivity is also computed over different regions of the GOM in an …
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Physical controls on copepod aggregations in the Gulf of Maine
… The summertime mean surface circulation and eddy kinetic energy are computed from a Lagrangian drifter dataset and an adaptive technique that allows for higher spatial resolution while also keeping uncertainty low. Eddy diffusivity is also computed over different regions of the GOM in an …
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Near-inertial internal Poincare waves in Lake Michigan: Seasonal variability and effects on lateral dispersion and turbulent mixing
… rate, the mixing efficiency and vertical eddy diffusivity are parameterized in terms of turbulent dimensionless parameters. The estimated dissipation rate ranged from 10<sup>-9</sup> – 10<sup> -6</sup> <em>m</em><sup>2</sup>/<em>s</em><sup>3</sup>. The vertical eddy diffusivity is …
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Transport of fluid from the boundary of a lake
… modes. Three methods showed that the vertical diffusivity was on the order of 10-6 m2 s-1. From the tracer surveys, the distance traveled offshore and velocity of the tracer was approximately 900 m and 0.8 cm s-1, respectively, with dispersion as the dominant transport mechanism. The horizontal …
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Numerical investigation of wire coil heat transfer augmentation
… heat transfer coefficient, Nusselt Number, and eddy diffusivity are used to draw conclusions regarding main transport mechanisms and optimal design parameters of the wire. The optimal parameter case, as determined by Collins et al. is analyzed here. This analysis confirms the conclusion of …
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Heat transfer to liquid metals, with observations on the effect of super-imposed free convection in turbulent flow
… to liquid metals requires values of the ratio of eddy diffusivities of heat and momentum, which may be obtained from temperature and velocity profiles measured in the flowing liquid metal. Temperature profiles have been reported by a number of workers, but these results are in poor agreement and …
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Internal flow subjected to an axial variation of the external heat transfer coefficient
… is selected through the velocity profile and eddy diffusivity. In examining turbulent flow, the effects of the parameters, Re and Pr, are considered.
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The vertical structure of the wind-driven circulation
… is an expression for the effective horizontal diffusivity produced by the interaction of vertical diffusivity and oscillatory vertical shear. Given an empirical velocity shear spectrum and an estimate of the vertical diffusivity this result could be used to calculate a horizontal eddy …
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A continental shelf bottom boundary layer model : the effects of waves, currents, and a movable bed
… current flow over a moveable sediment bed. An eddy diffusivity closure scheme that includes the effect of suspended sediment, temperature, and salinity induced stratification on the vertical turbulent diffusion of mass and momentum couples the resulting unsteady conservation equations for fluid …
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Oceanic microstructure observed near Bermuda using a towed sensor
… statistics for these events are presented. The eddy diffusivity has been calculated from the data to be approxima tely 0.075 cm2/sec.
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THE OBSERVED VARIATION OF COHERENT UPDRAFT OBJECTS WITH HEIGHT IN THE CONVECTIVE BOUNDARY LAYER
… these plume fluxes can be represented using "eddy-diffusivity mass-flux" (EDMF) parameterizations, wherein the "mass flux" is accomplished by a spectrum of buoyant plumes. In this presentation, we analyze the properties of ~120,000 coherent CBL updrafts recorded with a network of five Doppler …
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Dynamics of global ocean heat transport variability
… the time-dependent heat transport. The rectified eddy heat transport is calculated from the model. It is weak in the central gyres, and strong in the western boundary currents, the Antarctic Circumpolar Current, and the equatorial region. It is largely confined to the upper 1000 meters of the …
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Dynamics of global ocean heat transport variability
… the time-dependent heat transport. The rectified eddy heat transport is calculated from the model. It is weak in the central gyres, and strong in the western boundary currents, the Antarctic Circumpolar Current, and the equatorial region. It is largely confined to the upper 1000 meters of the …
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Rotating convection driven by differential bottom heating and its application
… in the North Atlantic when the vertical eddy diffusivity of heat is about 1cm2s-1. Naturally, this experiment is a only crude model of the oceanic convective circulation. We do not claim that the geostrophic scaling applies in detail to the oceans, however, it may have some important use …
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Phosphorous cycling in the Gulf of Maine : a multi-tracer approach
… found to range between 0.11 and 0.37. Vertical eddy diffusivity found using 7Be varied from 0.5 to 1.5 cm2 sec-I. Significant changes in phosphorus turnover rates within the reservoirs which contained 32p and 33p activity were found between the spring and summer months. In late summer, bacterial …
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Mixing in the North Atlantic Tracer Release Experiment : observations and numerical simulations of Lagrangian particles and passive tracer
… that on scales of 1 to 10 km small-scale diffusivity κs ≈ 3 m2s-1 and rms strain rate γ ≈ 3 X 10-7 s-1 . From the observed tracer distribution after one year, Ledwell (personal communication) further estimated that on scales greater than the mesoscale the effective eddy diffusivity κe ≈ 1 …
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Feedbacks between plants, flow, and particle fate
… displacement model (RDM) parameterized with an eddy diffusivity based on a simple set of physical parameters. This work filled a gap between field observations and traditional Lagrangian stochastic modeling, improving predictions of fungal spore escape to drive long range transport models. The …
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