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Showing 1 to 20 of 47 for “"URANS"”.
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A qualitative assessment and optimization of URANS modelling for unsteady cavitating flows
… Thus, Unsteady Reynolds-Averaged Navier-Stokes (URANS) models have been widely utilized as a workhorse for cavitating simulations. However, URANS models are unable to reproduce the periodic vapor shedding observed in experiments and thus, are often corrected by empirical correction. Recently, …
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A second generation URANS approach for application to aerodynamic design and optimization in the automotive industry
In the U.S., transportation is responsible for approximately 70% of all petroleum consumption and is now the largest source of carbon emissions and air pollution. Aerodynamics is an important aspect for energy saving and emission reduction in the automotive industry. In the design stage, …
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Aerodynamic comparison and validation of rans, K-ω, standard K-ɛ and URANS simulations of flat plate film-cooling
… on the numerical investigation of RANS and URANS analyses on a flat plate film cooling. The investigation aims to provide comparison between various turbulent models available for the Reynolds Average Navier Stokes (RANS) analyses and extended to unsteady Reynolds Average Navier Stokes …
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A methodology based on local resolution of turbulent structures for effective modeling of unsteady flows
… to unsteady Reynolds-averaged Navier-Stokes (URANS). This work investigates the key weaknesses of current hybrid approaches and develops a novel modeling strategy to overcome selected shortcomings. Hybrid approaches have mostly focused on identifying regions of the flow where LES could be …
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Dual Solver Computational Modeling of Ship-Helicopter Dynamic Interface Aeromechanics
… of an unsteady Reynolds-averaged Navier-Stokes (uRANS) solver with various lower-order computational aerodynamic solvers. Particularly promising for DI applications is the hybrid uRANS/free-vortex wake methodology, which uses uRANS to compute the rotor wake in the near-field and a potential flow …
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Numerical Simulations of Supercavitating Propellers and Hydrofoils
… cavitation pattern prediction capabilities of URANS and BEM solvers for supercavitating propellers (SCPs) and hydrofoils (SCHs) with non-conventional sectional profiles. The previously developed BEM at the VT Innovative Ship Design Lab (VT-iShip) is extended upon to allow for supercavitating …
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Turbine inlet non-uniformities and unsteady mechanisms
… the first, twodimensional calculations (RANS and URANS) are used to identify the mechanisms contributing to upstream stator wake attenuation through a turbine blade row. For a representative turbine rotor, pitch and time-averaged wake attenuation by 74% percent is demonstrated at one quarter chord …
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Three-Dimensional Unsteady Hydrodynamics of Tidal Turbines
… (VLM) and higher-order viscous modelling with URANS CFD. The VLM is used in the frequency-domain to perform a parametric study of a range of aerofoil geometries. The unsteady response of aerofoils with finite span, rotation or varying planform is shown to deviate strongly from 2D predictions by …
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Scale adaptive turbulence modeling for in-vessel sodium thermal hydraulics
… unsteady Reynolds-Averaged Navier-Stokes (URANS) and large eddy simulation (LES) models. Results indicate excellent potential for application of the STRUCT approach to sodium thermal striping flows. Best practice guidelines are developed and discussed.
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Numerical investigation of slat noise attenuation using acoustic liners
… an unsteady Reynolds-averaged Navier-Stokes (URANS) simulation using high-order spatial and temporal schemes for the wing without acoustic liners shows the presence of vortex shedding and associated high frequency acoustic sources behind the slat trailing edge. To evaluate the mitigating …
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Effiziente Simulation komplexer Strömungen auf semi-strukturierten Gittern
… wird der DES Ansatz im Vergleich zu einer URANS Simulation eingeführt. Bei beiden Testfällen wird deutlich, dass die Wiedergabe der physikalischen Vorgänge stark vom Turbulenzmodellierungsansatz abhängig ist. Gedruckte Version im Mensch & Buch Verlag Berlin [http://www.menschundbuch.de] …
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Investigation of velocity gradient as driving force of flow pulsation in fuel assemblies
… Washington University, was conducted with a URANS method in transient simulations using the commercial software Star-CCM+. A linear relationship was observed between crossflow mixing and [delta]vbulk, defined as the difference in bulk velocities of adjacent subchannels. A threshold value of …
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Simulation of partially premixed turbulent flames
… is found between the 2D unsteady RANS (URANS) results and experimental data for the flame transient evolution from its initial ignition to final stabilisation. The comparison for this transient evolution is improved significantly in the 3D URANS simulations suggesting that the third …
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Aerodynamics and Power Balance of Boundary Layer Ingesting Aircraft
… the Unsteady Reynolds-Averaged Navier-Stokes (URANS) approach. Using the computed flow field, a mechanical power balance was drawn up to analyse its performance and identify the loss sources. By varying the boundary conditions of the simulation and/or BLI fan rotational speed, the effects of …
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Improved Underwater Vehicle Control and Maneuvering Analysis with Computational Fluid Dynamics Simulations
… Unsteady Reynolds-averaged Navier-Stokes (URANS) simulations are used in conjunction with a 6-degree-of-freedom (6-DoF) rigid-body kinematic model to provide a numerical test basin for vehicle maneuvering simulations. The accuracy of this approach is characterized through comparison with …
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Eddy-resolving simulations of the flow around a vertical tail plane
… of the research consists of using unsteady RANS (URANS) simulations for VTP flows at high sideslip angles. The introduction of time-accuracy brings important benefits. Nevertheless, the results still show some inaccuracies (around 20% error). Finally, restarting from the flow solutions obtained by …
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Aerodynamic and Aeroacoustic Analysis of Low Reynolds Number Propellers Using Higher-Order RANS Transition Turbulence Modeling
… propellers. The rotor flow was examined using a URANS simulation with an overset grid. The objective was twofold: firstly, to validate the predictions generated by the proposed model for low-Reynolds number (low-$Re$) rotors, and secondly, to evaluate its effectiveness across a range of operating …
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U-series dating of diagenetically altered fossil reef corals and the application for sea level reconstruction
… gefolgt von teilweisem Verlust des aufgenommenen Urans erklärt werden können. Auf dieser Basis wird ein Korrekturverfahren (das Isochronenverfahren) entwickelt, das es ermöglicht, glaubwürdige Uranreihen-Alter für Korallen zu berechnen, die nicht mit den herkömmlichen Methoden datiert werden …
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Turbine tip clearance loss mechanisms
Three-dimensional numerical simulations (RANS and URANS) were used to assess the impact of two specific design features, and of aspects of the actual turbine environment, on turbine blade tip loss. The calculations were carried out for a subsonic high pressure turbine stage. The loss mechanism …
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Studies of turbulent flows in continuous casting of steel with and without magnetic field
… unsteady Reynolds-averaged Navier-Stokes (URANS) and steady Reynolds-averaged Navier-Stokes (RANS) with and without magnetic field to investigate turbulent flows in canonical as well as in the nozzle and mold geometries of the continuous casting process. The direct numerical simulations are …
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