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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 17 of 17 for “"turbulence generation"”.
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Examining Plasma Instabilities as Ionospheric Turbulence Generation Mechanisms Using Pseudo-Spectral Methods
Turbulence in the ionosphere is important to understand because it can negatively affect communication signals. This work examines different scenarios in the ionosphere in which turbulence may develop. The two main causes of turbulence considered in this work are the gradient drift instability …
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Effect of Boundary-Layer Tripping on Turbulence Generation and Trailing-Edge Noise in Transitional Airfoils
… that our prediction of the boundary layer and turbulence intensities are consistent with that of experimental results. Tripping, while it does modify the initial transition process, has little effect on the flow fluctuations near the trailing edge.</p> <p>The calculated spectra of the acoustic …
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Design and Evaluation of an Active Yaw and Turbulence Generation System to Produce Unsteady Flow in Automotive Wind Tunnels
… and testing of a novel unsteady yaw and turbulence generation system (TGS) for automotive wind tunnels that replicates on-road conditions using three combined subsystems. The focus of this thesis is primarily on one of the TGS subsystems, the unsteady yaw generation subsystem, which was …
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Investigation of the effect of a circular patch of vegetation on turbulence generation and sediment deposition using four case studies
… model vegetation and the effect of the patch on turbulence and mean flow. Two difference types pf vegetation were used along with two different stem densities totaling four different case studies. The spatial location of enhanced deposition correlated with the steady wake zone, which has length, …
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Investigation of the effect of a circular patch of vegetation on turbulence generation and sediment deposition using four case studies
… model vegetation and the effect of the patch on turbulence and mean flow. Two difference types pf vegetation were used along with two different stem densities totaling four different case studies. The spatial location of enhanced deposition correlated with the steady wake zone, which has length, …
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LDA and CTA in-cylinder measurements of intake-generated turbulence for steady flow around a centrally located valve
… to study the effects of swirl and valve lift on turbulence generation. A simple geometry was used for an initial look at the flow past a valve.;A cylinder with a centrally located valve was used as the test bed. The valve was tested at lifts of 4 and 9 mm Two intake geometries were tested: a …
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Exploration of Physics-Informed Grid Generation Technique for Wall-Modeled LES using Eagle3D
… technique utilizes a RANS solution to extract turbulence information, user-specified values related to resolution of turbulent energy levels, acoustics waves, and shock waves, to generate a point cloud for producing a lean WMLES grid with in-house solver, Eagle3D. WMLES solutions for the NASA …
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QUANTITATIVE VISUALIZATION OF CARBON DIOXIDE GAS TRANSFER AT A TURBULENT FREE SURFACE
… free surface in the absence of mean shear, with turbulence generated on the water side, well away from the free surface, which then transports itself to the free surface. This turbulence is generated far beneath the free surface by an array of upward-pointing synthetic jets which are each driven …
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Statistical Models for Extreme Events in Atmospheric Processes
… extremes events in rainfall and boundary layer turbulence, including contributions along three main lines of inquiry:</p><p>1) Developing extreme value models able to reduce estimation uncertainty in the case of short rainfall time series. To this end, a non-asymptotic approach is developed …
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Large Eddy Simulations of high Reynolds number Complex Flows with Synthetic Inlet Turbulence
… used with the synthetic eddy method for inlet turbulence generation can result in large savings in computational cost without any significant loss in accuracy when compared to wall resolved LES and experiments. In a turbulent channel flow at Re=45,000, computational complexity was reduced by a …
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Particle Motion in Flows: Contributions to Airborne Aerosol Measurement
… <p>The developed instrument consists of a low turbulence inlet and a laser-Doppler velocimeter to sample and measure the super-micron particles all in one unit. Air enters the inlet at true air speed of the aircraft, which is a relatively high speed in the range of 100-200 ms-1. The low …
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Computational Fluid Dynamics-Informed Analysis of Diaphragm-Free Shock Tubes and Insert Designs
… The impact of the valve on shock uniformity, turbulence generation, compression wave attenuation, and the overall test time performance is analyzed. Additional simulations at valve opening speeds of 5.08 m/s and 20.32 m/s examine valve speed effects under matched P4/P1 pressure ratios and …
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Exploring connections between seagrass ecosystem services and meadow hydrodynamics
… with the goal of predicting wave dissipation and turbulence generation. The flexibility of a plant is critical in defining its interactions with the environment. Seagrass plants deflect under currents, which streamlines the plants and reduces the parts of the plants directly experiencing the flow, …
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Two fluid numerical model for coastal applications
… hydro-morphodynamic processes such as turbulence generation and wave energy dissipation, run-up on the beach and overtopping of coastal defence structures. During breaking, waves are complex mixtures of air and water (“white water”) whose properties affect velocity and pressure fields …
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Unsteady Flow Behaviors Generated by Three-Dimensional Lattice Geometries as Measured by Laser Doppler Velocimetry
<p>"The relation between flow stream turbulence and heat transfer has been known for a long time, that the heat transfer rate is increased if the turbulence or fluctuation level of the flow increases. Open cell foams and compact heat exchangers are two of the most common models applied for heat …
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3-D Numerical Modeling of Turbidity Currents
… insights into current dynamics including turbulence structures and their ef- fects on deposit thickness, grain size, and distribution pattern. Proper modeling of turbulence in these stratified flows is crucial to accurately predict the turbulence en- ergy budget, which consequently affects …
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Numerical Modeling of Synthetic Vortical Disturbance Interactions Using OpenFOAM
… field (such as a time-harmonic gust or turbulence with required characteristics) is employed. Validation test studies are conducted to examine and compare with previous results for the benchmark case of 2D time-harmonic gust interaction with NACA0012 airfoil, and then the case of the …