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 155 for “"Pressure Gradients"”.
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Wave Induced Vertical Pore Pressure Gradients at Sandy Beaches
… be considered. Among these many processes, pore pressure gradients within sandy beach sediments affect sediment transport by reducing the sediment's effective stress to zero (this process is called liquefaction). Despite the known importance of these pressure gradients with respect to sediment …
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Numerical Simulation of Vortex Generating Jets in Zero and Adverse Pressure Gradients
… blowing of angled jets, subjected to a zero pressure gradient, yielded excellent agreement with the PIV data in terms of vortex formation and strength. Observed flow features include primary and secondary vortices, where the primary vortex eventually dominates the downstream region. A shell …
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Experimental and numerical studies of flows over forward facing steps in pressure gradients
… and numerical studies of the effects of adverse pressure gradients (APG) and Reynolds numbers on flows over forward facing steps (FFS). For the experimental work, particle image velocimetry was used to conduct velocity measurements at several locations downstream of the FFS. Proper orthogonal …
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A turbulence model for steady and unsteady boundary layers in strong pressure gradients
… and unsteady boundary layers in strong adverse pressure gradients is described. The model is developed in a rational way based on an understanding of the flow physics obtained from recent experimental observations. The turbulent shear stress is given by a mixing length model, but the variation …
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Some features of surface pressure fluctuations in turbulent boundary layers with zero and favorable pressure gradients
… are interested in the structure of the surface pressure fluctuations for the development and use of noise prediction techniques for helicopter and turbomachinery rotors. This study, conducted in the Virginia Tech low speed boundary layer wind tunnel, covered the effects of zero and favorable …
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The use of soft lithography to reproduce snail-like movement by creating pressure gradients in thin films
By imitating nature, man finds ways to expand his capacities. To achieve this aim, he often takes natures designs, simplifies them to their most basic principles and then works in a retrograde fashion to add back the complexity originally stripped away to make the first discoveries. This thesis is …
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Mean Flow Characteristics and Turbulent Structures of Turbulent Boundary Layers in Varying Pressure Gradients and Reynolds Numbers
… studied to understand the influence of varying pressure gradients and flow Reynolds number on the boundary layer growth and mean turbulent properties. The test was conducted in the Virginia Tech Stability Wind Tunnel with a 0.914 m chord length, NACA 0012 Airfoil in the test section. This …
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The effect of particle size and density on pressure gradients in horizontal pipelines in lean phase pneumatic conveying
… need to improve the accuracy of predicting the pressure losses along pneumatic conveying systems, and in particular, an investigation into the reasons why materials behave differently to each other when conveyed pneumatically along pipelines. It was intended that the information obtained from …
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Modelling large scale ocean circulation : the role of mixing location and meridional pressure gradients for the Atlantic overturning dynamics
… of the AMOC with a key quantity, the meridional pressure difference is analyzed. Due to the application of a very low diffusive tracer advection scheme, a realistic Atlantic overturning circulation can be obtained that is purely wind driven. On top of the winddriven circulation, changes of …
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A comparison between the pressure gradients in vertical and horizontal pneumatic conveying, with an investigation into the effect of pipeline bore in vertical conveying
… present, the commonly used method to predict the pressure drop in a vertical pipeline in a pneumatic conveying system is to obtain the pressure gradient in a horizontal for the identical conveying conditions and double the pressure gradient in the horizontal pipeline to give the pressure gradient …
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Acoustic Stimulation of Multiphase Flow in Porous Media
… Galerkin finite element method for both steady pressure gradients and the oscillatory pressure gradients that arise during acoustic stimulation. Owing to interfacial effects, the calculations for constant pressure gradients reveal a nonlinear dependence of the flow rate on the applied pressure …
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Net Flow Through Soft Porous Media Generated by a Periodic Mean-Zero Pressure Gradient
… the effect of applying periodic mean-zero pressure gradients to a soft porous medium. These periodic mean-zero pressure gradients are composed of square waves, with a high magnitude positive pressure drop applied for 1/3 of the period and a negative pressure drop with half the magnitude …
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Trailing Edge Flow Conditions as a Factor in Airfoil Design
… the ramifications of the unbounded trailing edge pressure gradients generally present in the potential flow solution of the flow over an airfoil are examined, and the conditions necessary to obtain a class of airfoils having finite trailing edge pressure gradients developed. The incorporation of …
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Evaluation of Turbulence Models for Unsteady Separation
… many physical flows due to time-varying adverse pressure gradients. This phenomenon may result in increased drag, decreased lift, and loss of efficiency or failure in flow devices. It is, therefore, important to predict and analyze unsteady separation in the design of flow devices. Turbulence …
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Turbulent Boundary Layer Flow Over a Bump
… While two-dimensional (2D) TBLs under zero-pressure-gradient (ZPG) conditions are well understood, real-world boundary layers often experience complex three-dimensional (3D) effects due to surface curvature and pressure gradients. These conditions introduce flow skewing, anisotropy, and …
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Skin friction measurements around a wing-body junction using oil- film laser interferometry
… arising from three-dimensional effects and pressure gradients. The oil-film, dual-beam laser interferometer was constructed to measure the skin friction around a wing-body junction in a three-dimensional, turbulent boundary layer with pressure gradients. The flow was dominated by the …
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Pressure Gradient Effects in the Viscous Wall Region of a Turbulent Flow
… a study investigating the effects of an imposed pressure gradient on the viscous wall region of a turbulent flow are presented. Only imposed pressure gradients homogeneous in the streamwise direction are considered.
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Mitigating Engine Unstart in Scramjets with Porous Bleeders
… of porous bleeder design parameters such as pressure jump coefficient and bleeder size on isolator effectiveness and unstart prevention was evaluated. Results indicated that porous bleeders delayed flow separation and reduced adverse pressure gradients, thereby enhancing isolator performance. …
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Horizontal pressure gradient and bed shear stress under double dam-break driven swash and validation of a Reynolds-Averaged Navier-Stokes equations based model
… morphodynamics through sediment transport gradients. Sediment transport rates are often estimated using bed shear stress as the main hydrodynamic driver. However, the importance of pressure gradients relative to bed shear stress in the swash zone is still poorly known. Thus, it is important …
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Study of Far Wake of a Surface-Mounted Obstacle Subjected to Turbulent Boundary Layer Flows
… Reynolds number of the flow and manipulating the pressure gradient distributions using a NACA 0012 airfoil placed within the wind tunnel test section. The measurements were acquired utilizing a spanwise traversing boundary layer rake and a point pressure sensing microphone array. The findings …
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