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 105 for “"Direct numerical simulations"”.
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Direct numerical simulations and experimental investigation of dielectrophoresis
This dissertation deals with the numerical and experimental studies of the phenomenon of dielectrophoresis, i.e., the motion of neutral particles in nonuniform electric fields. Dielectrophoresis is the translatory motion of neutral particles suspended in a dielectric medium when they are subjected …
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Direct numerical simulations of separated and separated-reattaching flows on massively parallel processing computers
Direct numerical simulations of separated-reattaching and separated flows have been performed on massively parallel processing computers. Two basic geometrical configurations have been studied: the separated-reattaching flow past a normal flat plate with an attached downstream splitter plate and …
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Direct numerical simulations of multiphase flow with applications to basaltic volcanism and planetary evolution
… purposes. This thesis studies the potential of direct numerical simulations for advancing our fundamental understanding of the multiphase flow dynamics in magmatic flow. It is divided into two parts. The first part investigates gas-fluid coupling during the buoyant ascent of an exsolved gas …
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Phase-resolved reconstruction and forecast of nonlinear irregular wave field based on direct numerical simulations
… and reasonable assumptions of the frequency and directional extent of the wave field, we obtain closed-form expressions for (linear) predictable zone PL in terms of set notation involving the individual measurement. We derive and illustrate PL obtained for ("probe") measurements at one or more …
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Tensile and Flexure Strength of Unidirectional Fiber-Reinforced Composites: Direct Numerical Simulations and Analytic Models
… developed by Curtin and co-workers for the numerical simulation of tensile stress-strain behavior in fiber-reinforced composites is used to predict the tensile strength of metal matrix composites consisting of a Titanium matrix and unidirectionally aligned SiC fibers. This model is extended …
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Effect of self-stratification on channel flows and boundary layers: a study using direct numerical simulations
… due to self-stratification was aided by Direct Numerical Simulation (DNS) simulations for a simplified formalism of the flow [Cantero et al. 2009] and the present study aims at furthering that work. In the present study, sediment is assumed to be non-cohesive in nature and possessing a …
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Study of the role of differential diffusion and equation of state on the features of stably stratified turbulent channel flow using direct numerical simulations
… of turbulence. In this study, results from direct numerical simulations of stably stratified turbulent channel flow under moderate levels of differential diffusion and two types of EoS are examined in terms of instantaneous, statistical, spectral, and modal features of the flow field. The …
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Computer aided floating zone growth of Germanium-Silicon crystals in a resistance heated multi-zone furnace
… International Space Station. By using global simulations and <br>the inverse modeling method, its optimal design and its <br>performance could be obtained. By means of direct numerical simulations, the influence of solutal Marangoni convection on species transfer in a floating <br>zone could …
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Investigation of mean flow and vertical vorticity in turbulent convection using spectral simulations on massively parallel processors
Direct numerical simulations of Rayleigh-Benard convection are performed at several values of Rayleigh number (Ra). The computational domain consists of a square-planform rectangular box with horizontal-to-vertical aspect ratio equal to four. This domain is periodic in the horizontal directions, …
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Growth Suppression in Simulated Compressible Turbulent Mixing Layers
Direct numerical simulations of turbulent flows require numerical schemes with high resolution and grid flexibility. Resolution properties of B-spline and compact finite-difference schemes are evaluated using Fourier analysis in periodic domains, and tests based on solution of the wave and heat …
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Stochastic estimation of near-wall closure in turbulence models
… to formulate boundary closure models for the numerical large eddy simulation (LES) of turbulence. The stochastic estimation method resolves coherent structure of the wall layer using empirical correlation functions, and provides an accurate estimation of the wall layer characteristics. As in …
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Spectral Energy Dynamics and Wavevector Resonance in a Weakly Nonlinear Chaotic Elastodynamic Billiard
… is made between the theory and results of direct numerical simulations performed for an ensemble of two-dimensional rough-wall billiards. The frequency profile of the mode-coupling strength is verified.
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Study of Three-Dimensional Vortex Shedding in the Wake of a Square Cylinder
… may explain the complicated behavior observed in direct numerical simulations of the non-linear three-dimensional Navier-Stokes equations at low Reynolds numbers.
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A self corrective vortex fluxing method for viscous fluid structure interaction problems
… This enables highly accurate, robust Direct Numerical Simulations by relaxing the need for small timesteps and allowing the use of coarse regular computational grids. The methodology was validated for rigid, rotating and deforming bodies.
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The instability of axial-symmetric gravity-capillary waves generated by a vertically-oscillating sphere
… phenomenon using theoretical analysis and direct numerical simulations. We first theoretically show that for an arbitrary three-dimensional body floating in an unbounded free surface, there exists a set of homogeneous solutions at any frequency in the gravity-capillary wave context.
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Numerical investigation of turbulent combustion regimes on localized forced ignition using stratified combustible mixture
… of turbulent stratified mixtures has been numerically analyzed based on three- dimensional Direct Numerical Simulations (DNS) for different values of Karlovitz number (Ka) corresponding to different turbulent combustion regimes. The initial values of turbulent fluctuations and the integral …
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A Generalized Model for Wall Flame Heat Flux During Upward Flame Spread on Polymers
… this study. Flame heat flux predictions from FDS direct numerical simulations were also compared to the generalized model predictions in an exploratory manner and found to be similar.
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Laser diagnostic investigation of the structure of steady and driven hydrogen jet diffusion flames
… profiles are compared with the results of direct numerical simulations (DNS) of the flames. From a comparison of measured and calculated temperatures in steady, laminar, H$\sb2$ jet diffusion flames, thermal diffusion was found to be a significant effect. The experimental and computational …
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Characteristics of flame-turbulence interactions in freely propagating turbulent premixed flames under decaying and forced isotropic turbulence conditions
… unsteady, and multi-scale processes. Previous numerical studies of freely propagating flames have utilized either forced or decaying background isotropic turbulence to provide detailed insights into the features of flame-turbulence interactions; however, none have made direct comparisons of …
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