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  • Numerical simulation of cavitating bubble-laden turbulent flows

    Creator:
    Shams Sobhani, Ehsan
    Abstract:
    Many engineering devices and propulsion systems suffer from undesirable effects of cavitation; such as degradation in the efficiency of pumps and turbines, generation of noise and vibration on ship propeller, increased drag and erosion of propeller blade, etc. In spite of decades of research on this problem, detailed study of...
    Resource Type:
    Dissertation
    Full Text:
    unstructured grid finite volume solver. Large Eddy Simulation technique with dynamic Smagorinsky subgrid model

  • A multiscale modeling approach for bubble-vortex interactions in hydro-propulsion systems

    Creator:
    Finn, Justin Richard
    Abstract:
    Multiphase flow dynamics are important in many naval and turbomachinery applications, where bubble interaction with low pressure, vortical structures can lead to undesirable cavitation effects. To better understand the underlying phenomena, a multiscale numerical framework is developed to simulate bubble laden flow in dynamic hydro propulsion systems. Several subproblems in...
    Resource Type:
    Masters Thesis
    Full Text:
    Discrete Element Model (DEM) is applied to flows where the bubbly phase is not resolved by the grid

  • Shear and convective turbulence in a model of thermohaline intrusions

    Creator:
    Mueller, Rachael
    Abstract:
    Thermohaline interleaving is an important mechanism for laterally fluxing salt, heat, and nutrients between oceanic water masses. Interleaving is driven by a release of potential energy resulting from the vastly differing diffusivities of heat and salt in seawater. The flows are composed of stacked intrusions that flux more buoyant and...
    Resource Type:
    Masters Thesis
    Full Text:
    Turbulence in a Model of Thermohaline Intrusions Abstract approved: William D. Smyth Thermohaline

  • A study of micro-scale, fractal-like branching flow networks for reduced pumping power and improved temperature uniformity

    Creator:
    Alharbi, Ali Y.
    Abstract:
    A first generation, one-dimensional predictive model is proposed for designing heat sinks with fractal flow networks. A three-dimensional computational fluid dynamics (CFD) model is analyzed as a means for validating the model and identifying areas for improvement. Two separate CFD models were developed. One was analyzed with conjugate heat transfer...
    Resource Type:
    Masters Thesis
    Full Text:
    numbers above 150. Bau (1997) demonstrated, using a mathematical model, that a variable cross sectional

  • Proportional integral derivative control of an oil-heated fractal-like branching microchannel desorber

    Creator:
    Davis, Keith R.
    Abstract:
    A PID controller was designed to control the performance of an oil-heated fractal-like branching microchannel desorber for use in an ammonia-absorption refrigeration system. Both the amount and concentration of ammonia refrigerant generated at the desorber can be controlled by choosing the rectified circulation ratio as the controlled variable in a...
    Resource Type:
    Masters Thesis
    Full Text:
    mathematical model of the dynamic relationship between oil pump control voltage and rectified circulation

  • Nonlinear model reduction using the group proper orthogonal decomposition method

    Creator:
    Dickinson, Benjamin T.
    Abstract:
    Proper orthogonal decomposition (POD) in conjunction with the Galerkin projection has been used as a model reduction technique for the tractable real-time control of high-dimensional systems. While POD based model reduction may improve the tractability of high-dimensional models, the nonlinear POD based model may be impractical for control due to...
    Resource Type:
    Masters Thesis
    Full Text:
    Master of Science in Mechanical Engineering presented on May 9, 2007. Title: Nonlinear Model Reduction

  • A unified model of one-dimension two-fluid horizontal flows and its stability analysis

    Creator:
    Kim, Dong-Wan
    Abstract:
    An improved version of the one-dimensional horizontal two-fluid flow model has been developed by incorporating physical terms for gravity and local void fraction profiles. Introduction of an interface mixing layer concept allows the one-dimensional two-fluid model to remain hyperbolic. This will overcomes a major obstacle in using the current one-dimensional...
    Resource Type:
    Dissertation

  • RANS and LES predictions of turbulent scalar transport in dead zones of natural streams

    Creator:
    Drost, Kevin J.
    Abstract:
    Natural stream systems contain a variety of flow geometries which contain flow separation, turbulent shear layers, and recirculation zones. This work focuses on streams with dead zones. Characterized by slower flow and recirculation, dead zones are naturally occurring cutouts in stream banks. These dead zones play an important role in...
    Resource Type:
    Masters Thesis
    Full Text:
    simulated using the RANS turbulence model with the standard k-ω closure. The standard first order dead

  • Development of a Cartesian-grid-based solver for an oscillatory boundary layer over a rough wall

    Creator:
    Skitka, Joseph M.
    Abstract:
    Predominant models for predicting rates of sediment transport face acute shortcomings when applied to coastal boundary layers. This is due to a neglect of the web of stochastic variables governing the rate of sediment dislodgement. While stochastic models do exist, the parametric extent of their validity tends to be limited,...
    Resource Type:
    Masters Thesis
    Full Text:
    forces in transitional and early turbulent regimes. The implications of these findings on model

  • A numerical study of inertial flow features in moderate Reynolds number flow through packed beds of spheres

    Creator:
    Finn, Justin Richard
    Abstract:
    In this work, flow through synthetic arrangements of contacting spheres is studied as a model problem for porous media and packed bed type flows. Direct numerical simulations are performed for moderate pore Reynolds numbers in the range, 10 ≤ Re ≤ 600, where non-linear porescale flow features are known to...
    Resource Type:
    Dissertation
    Full Text:
    contacting spheres is studied as a model problem for porous media and packed bed type flows. Direct numeri