Flow Features in a Fully Developed Ribbed Duct Flow as a Result of Les

Lohász, Máté Márton; Rambaud, Patrick; Benocci, C.

doi:10.1016/b978-008044544-1/50025-x

Cited by 8 publications

(7 citation statements)

References 42 publications

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“…For the analysis of complex three-dimensional flow fields, obtained either from measurements or from numerical simulation, several methods have been developed and are widely used nowadays, see e.g. LOHÁSZ et al (2006). In this study, visualization with streamlines and detection of vortex cores were performed.…”

Section: Effect Of Tree Planting On the Wind Field In Street Canyonsmentioning

confidence: 99%

Numerical modeling of flow and pollutant dispersion in street canyons with tree planting

Bálczó¹,

Ruck²

2009

metz

105

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Numerical simulations of the impact of tree planting on airflow and traffic pollutant dispersion in urban street canyons have been performed using the commercial CFD (Computational Fluid Dynamics) code MISKAM. A k-ε turbulence model including additional terms for the treatment of vegetation, has been employed to close the Reynolds-averaged-Navier-Stokes (RANS) equations. The numerical results were compared to wind tunnel data. In the case of the investigated wind direction perpendicular to the street axis, the presence of trees lead to increased pollutant concentrations inside the canyon. Concentrations increased strong on the upstream side of the canyon, while on the downstream side a small concentration decrease could be observed. Lower flow velocities and higher pollutant concentrations were found in the numerical simulations when directly compared to the experimental results. However, the impact of tree planting on airflow and concentration fields when compared to the treeless street canyon as a reference configuration were simulated quite well, meaning that relative changes were similar in the wind tunnel investigations and numerical computations. This feature qualifies MISKAM for use as a tool for assessing the impacts of vegetation on local air quality. Zusammenfassung Numerische Simulationen über die Auswirkungen von Baumpflanzungen auf die Strömungsverhältnisse und die Ausbreitung von Verkehrsemissionen in städtischen Straßenschluchten wurden mit dem kommerziellen CFD (Computational Fluid Dynamics) Code MISKAM durchgeführt. Ein k-ε Turbulenzmodell mit speziellen Zusatztermen zur Vegetationsberücksichtigung kam zum Einsatz um die Reynoldsaveraged-Navier-Stokes (RANS) Gleichungen zu schließen. Die numerischen Berechnungsergebnisse wurden mit Windkanalergebnissen verglichen. Im Fall der untersuchten Windrichtung senkrecht zur Straßenlängsachse führten die Baumpflanzungen zu im Mittel höheren Konzentrationen innerhalb der Straßenschlucht. Deutliche Konzentrationszunahmen waren an der leeseitigen Straβenschluchtwand zu verzeichnen, während an der luvseitigen Wand nur geringe Konzentrationsabnahmen zu beobachten waren. Die numerischen Simulationen ergaben geringere Windgeschwindigkeiten und höhere Schadstoffkonzentrationen gegenüber den experimentellen Ergebnissen. Jedoch wurden die Auswirkungen von Baumpflanzungen auf die Strömungs-und Konzentrationsfelder insofern zufriedenstellend simuliert, als dass die relativen Änderungen im Vergleich zur baumfreien Straßenschlucht als Referenzfall eine gute Übereinstimmung mit den Windkanalmessungen aufwiesen. Somit erweist sich MISKAM geeignet den Einfluss von Vegetation auf die Luftqualität im Straβenschluchtbereich einzuschätzen.

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Section: Effect Of Tree Planting On the Wind Field In Street Canyonsmentioning

confidence: 99%

Numerical modeling of flow and pollutant dispersion in street canyons with tree planting

Bálczó¹,

Ruck²

2009

metz

105

View full text Add to dashboard Cite

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“…This assumption also necessitates hot-wire anemometer measurements over the blade surface and in the wake, in order to examine the correlation between sound pressure and turbulence spectra. Computational aero-acoustics with involvement of Large Eddy Simulation (17) also support such investigations. The further research plan involves the following aspects.…”

Section: Combination Of Acoustic and Aerodynamic Aspects: Further Resmentioning

confidence: 93%

Study of the Aero-Acoustic and Aerodynamic Effects of Soft Coating upon Airfoil

Vad

Koscsó

Gutermuth

et al. 2006

JSME Int. J., Ser. C

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Comparative acoustic and wind tunnel experiments were carried out on uncoated and coated isolated airfoils. The aim of the tests was to survey the airfoil noise reducing effect and the aerodynamic impact of the acoustically soft coating consisting of filaments, as a preliminary study in application of such coatings to axial flow turbomachinery bladings. It was found in the acoustic tests that the coating successfully reduces the sound pressure in the frequency range critical from the aspect of human audition. The wind tunnel experiments included laser Doppler anemometer studies on the development of the boundary layers and on the wake structure, and static pressure measurements on the blade surface and in the wake. The coating reduced the lift and increased the drag. A proposal has been made for further studies in order to retain the advantageous acoustic effects of the coating while avoiding the undesirable aerodynamic impact.

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“…4 on the centre plane Z/h=0. The LES of Lohász et al [7] in a red dashed line. The experimental results plotted with black squares and the present simulation in black dotted/dashed line show a very good agreement.…”

Section: Resultsmentioning

confidence: 99%

“…The flow is affected by the sidewall and a three-dimensional representation is needed. Among the studies, which consider 3D flow, one may list: Murata and Mochizuki [2], Watanabe and Takahashi [3], Tafti [4], the large-eddy simulations carried out by Lohász et al [5][6][7] reproduce the experiments of Casarsa et al [1] without taking into account the heat transfer. All of the papers mentioned above solve the Navier-Stokes equations for an incompressible flow and a temperature equation which acts like a passive scalar.…”

Section: Introductionmentioning

confidence: 99%

Heat transfer in a ribbed square duct by Large-Eddy-Simulation

Labbé¹

2007

WIT Transactions on Modelling and Simulation, Vol 46

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Large-eddy simulation is used to understand the flow in a square ribbed duct representative of systems designed for internal cooling of turbine blades. The presence of ribs increases turbulence levels and enhances heat transfer. The objective of the present LES study is to solve three-dimensional Navier-Stokes equations for a compressible flow to enable simulations for which the temperature variation within the flow is very significant. This simulation allows us to deal with a fully developed turbulent flow and heat transfer in a ribbed channel with a high blockage ratio, whose parameters are chosen to reproduce the experiments of Casarsa et al. "Characterization of the velocity and heat transfer fields in an internal cooling channel with high blockage ratio." Proceedings of ASME TURBO EXPO 2002 June 3-6, Amsterdam, The Netherlands, 2002. The simulation is restricted to one pitch length and periodic conditions are applied in the streamwise direction. Mean and turbulent quantities are presented, together with the heat transfer.

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Flow Features in a Fully Developed Ribbed Duct Flow as a Result of Les

Cited by 8 publications

References 42 publications

Numerical modeling of flow and pollutant dispersion in street canyons with tree planting

Numerical modeling of flow and pollutant dispersion in street canyons with tree planting

Study of the Aero-Acoustic and Aerodynamic Effects of Soft Coating upon Airfoil

Heat transfer in a ribbed square duct by Large-Eddy-Simulation

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