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 33 for “"fluid models"”.
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Deterministic Fluid Models for Internet Congestion Control
We then study the impact of parameter choice of an AQM (active queue management) scheme that can be used at the router. We argue that, depending upon the choice of the parameters of the AQM scheme, one would obtain a rate-based model or a rate-and-queue-based model as the deterministic limit of a …
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A variational multiscale framework for non-Newtonian fluid models
… finite element formulations for non-Newtonian models for complex fluids. One class of non-Newtonian fluids is shear-rate dependent fluids that include nonlinear viscosity functions of the second invariant of the rate-of-deformation tensor, thereby resulting in shear-thinning or shear-thickening …
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Impact of ion-neutral collisions in fluid models of plasma sheath
… of an improved one-dimensional self-consistent fluid modeling of argon plasmas in DC discharges, including the sheath regions, is presented. Comparison of the charged species density, electron mean energy, plasma potential and ion velocity profiles with the profiles obtained by other fluid …
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Two-fluid simulations of magnetic reconnection with a kinetic closure for the electron pressure anisotropy
… region and the electron current layer. Previous fluid models and simulations fail to account for this anisotropy. In this thesis, new equations of state that accurately describe the electron pressure anisotropy in cases of sufficiently strong guide magnetic field are implemented in fluid …
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Fluid and gas models in FLRW and almost FLRW universes
… been modeled in the covariant sense, in terms of fluid models and perturbations thereof, leading to Gauge Invariant Covariant (GIC) perturbations of these fluid models. It is well known that kinetic theory provides a physically sound and consistent description of the matter and radiation in the …
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A controllably adhesive climbing robot using magnetorheological fluid
… the novel adhesive effects of magnetorheological fluid for use in climbing robotics were experimentally measured and compared to existing cohesive failure fluid models of yield stress adhesion. These models were found to correlate with experimental results at yield stresses below 1.12 kPa. MR …
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Large Eddy Simulation Based Turbulent Flow-induced Vibration of Fully Developed Pipe Flow
… thesis focuses on the development of a numerical Fluid-Structure Interaction (FSI) model that will help define the relationship between pipe wall vibration and the physical characteristics of turbulent flow. Commercial FSI software packages are based on Reynolds Averaged Navier-Stokes (RANS) fluid …
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Theory for hydrostatic gas journal bearings for micro-electro-mechanical systems
… investigate the underlying physical mechanisms, fluid models are established to analytically calculate the hydrostatic, hydrodynamic, and damping bearing forces. It is found from first principles that the hydrodynamic force due to viscous drag becomes dominant with an L/D<<1 and acts in the …
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Experiments in a rotating source-sink annulus
An experimental investigation of the different flow regimes in a rotating source-sink annulus is described. Both the steady and transient velocities are measured over a large range of Ekman Reynolds number and Rossby number. Differing probe configurations are used to investigate the corresponding …
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Self-consistent Monte Carlo simulations of plasma processing reactors
… collide with an energy-resolved electron fluid. The modified null-cross-sectional technique is employed, making the MC simulation computationally tractable. The model is used to study ECR reactors and is a hybrid MC fluid model. The MC simulation generates details of the EED and the fluid …
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Slowly varying pipe flow of thixotropic fluids
… flows of thixotropic and antithixotropic fluids in two flow problems: unsteady flow in a slowly varying 3D pipe, and oscillating flow in a uniform cylindrical pipe. We consider two fluid models which exhibit interesting non-Newtonian behaviour: the viscous Moore-Mewis-Wagner (MMW)model, …
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Dynamic travel time models for pricing and route guidance : a fluid dynamics approach
… As a result, our goal is not only to develop models for travel times as they arise in a variety of dynamically evolving environments, but also to investigate the application of these models in the contexts of dynamic pricing, inventory management, traffic control and route guidance. To address …
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The influence of time-dependent material behavior on the response of sandwich beams
… segmented reflectors, simple sandwich beam models are developed. The beam models included layers representing face sheets, core and adhesive. The issue of time-dependency is essential because the expected life of a reflector is on the order of 20 years. Using the principle of stationary …
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Particle-Resolving Simulations of Dune Migration: Novel Algorithms and Physical Insights
… generated therein, the closure terms in the two-fluid models or hydro-morphodynamic models can be improved, which can contribute to the numerical modeling of sediment transport in engineering scales.
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The extrusion processing of instant coffee for the purposes of creating a pressurised microstructure
… to the behaviour of bubbles within the fluid. The experimental technique was supplemented by analytical and computational modelling of the pressure losses in the system, to improve data processing accuracy. Additional thermal and mechanical tests were performed to obtain as much of the …
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Regularity and Numerics for stochastic p-Laplace and symmetric p-Stokes systems
… for the solution variable. <br /><br /> Both models are related to non-Newtonian fluids, more specifically, power-law fluids. We discuss the derivation of fluid models for non-Newtonian fluids based on physical principles. In particular, we highlight the natural occurrence of stochasticity in …
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Plasma flow and acceleration in the magnetic mirror and nozzle geometries
… the Laval nozzle. The Magnetohydrodynamic (MHD) fluid code {\it PLUTO} and the Particle-in-Cell (PIC) code {\it {\it VSim}} are employed to simulate plasma dynamics in both the nozzle and its expander region. The first part of the study utilizes the {\it PLUTO} MHD code to analyze the axial …
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Direct simulations of cells motions and deformations in flow
… Leukocytes are represented by two composite fluid models. The first model is the compound-drop model in which the cytoplasm and the nucleus are modeled as fluids, and the second one is the drop-rigid-particle model in which the cytoplasm is modeled as a fluid and the nucleus as a rigid …
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Simulation methods for polydisperse, multiphase flows using moment methods
… to solve bubbly flows using the standard two fluid model coupled to the moment transport equations of a monokinetic number density function (NDF). This provides the stability of a two-fluid solver, while adding additional accuracy that comes from the inclusions of a range of sizes, and …
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Improvement of Labyrinth Seal Leakage Rates Using Additive Manufacturing
… turbomachinery. Labyrinth seals have a torturous fluid path with high losses, thus limiting the amount of fluid leakage. These types of seals can be non-rotating, allowing them to better take advantage of the additive manufacturing process due to the absence of rotating stresses. Labyrinth seal …
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