LES

Abstract The paper presents a comparative analysis of recent simulations, conducted in the framework of a French-German collaboration on LES of Complex Flows, for the so-called Ahmed body at Reynolds number 768000 and slant angle 25. It provides a juxtaposition of ...

Het Grafisch Lyceum te Utrecht. wil graag dé topvakschool van Nederland worden en heeft breed ingezet om de kwaliteit van haar onderwijs en docenten te verbeteren. Guido Romeijn docent en onderzoeker aan de Mbo-opleiding Interactieve Vormgeving aan het Grafisch Lyceum te Utrecht, heeft samen met docenten en studenten van zijn school collectief praktijk onderzoek gedaan naar de best practices binnen zijn opleiding om antwoord te vinden op de vraag:

Wat kan de organisatie van het GLU leren van de succesfactoren uit best practice lessen?

Hiervoor heeft de onderzoeker gebruik gemaakt van een metafoor. Hij vergelijkt het proces in de les namelijk met het complexe proces van kernfusie. Pas als de factoren die van invloed zijn op de les werkelijk in dienst staan van de les kan er volgens hem fusie tot stand komen en kunnen flow (Csikszentmihalyi, 1999), best practices en goed onderwijs ontstaan.

Het onderzoek is methodisch uitgewerkt met een theoretische kader dat vertrekt vanuit de positieve psychologie:
Hierin wordt gesteld dat de onderwijskwaliteit voor een belangrijke mate van binnenuit de docent komt. De intrinsieke kwaliteiten van de docent liggen namelijk voor een belangrijk gedeelte vast in de krachten en deugden (Peterson & Seligman, 2004). Daarnaast bepalen talenten, ervaringen en vakmanschap in belangrijke mate het beroepsgerichte handelen, waarin docenten in hun element (Robinson & Aronica, 2009) kunnen zijn. De mate waarin docenten in staat worden gesteld om zelf meester en eigenaar kunnen zijn van hun vak bepaalt in belangrijke mate de intrinsieke motivatie of drive van docenten (Pink, 2010).
Binnen het Ui-model van Korthagen & Vasalos (2007) wordt vervolgens aangetoond dat factoren die wrijving opleveren bij docenten in de uitvoering van de les naar buiten toe toenemen en zich vooral bevinden in de georganiseerde en gefaciliteerde omgeving waarin de docent met zijn les functioneert.
Binnen het Activiteitensysteemmodel van Engeström (Akkerman, 2012) wordt aangetoond wordt dat een school op diverse niveaus daadwerkelijk wat kan doen aan de onderwijskwaliteit door de factoren die de les beïnvloeden te bestuderen en van de uitkomsten te leren.
Appreciative Inquiry oftewel waarderend onderzoek doen naar deze factoren is een belangrijke sleutel tot innovatie, door open te staan voor wat er werkt binnen de school en innovatie van binnenuit te laten komen (Masselink et al., 2008).

De onderzoekers zijn middels bestudering van bestaande documenten (lesevaluaties, studenten interviews) en diverse brainstorm bijeenkomsten gekomen tot een lijst van 94 factoren die de les beïnvloeden, verdeeld over 6 hoofdgroepen (docent, student, inhoud, sfeer, tijd, omgeving). Op de vraag in de vragenlijst aan studenten en docenten: Welke factoren waren bepalend voor deze best practice? zijn uit de antwoorden alle best practices, best practice docenten en succesfactoren van de opleiding in kaart gebracht.

Op basis van generieke (opleidingsniveau) en specifieke interpretaties (docent- en lesniveau) op de uitkomsten van vragenlijst, is een aantal best practice docenten geïnterviewd om te kunnen leren van hun inzichten op de (succes)factoren. Aan de hand van de persoonlijke reflecties en uitspraken die de geïnterviewde docenten hebben gedaan op de factoren die uit de vragenlijsten naar voren kwamen valt op te maken dat de factoren te onderscheiden zijn in twee gemeenschappelijke eigenschappen waarop de organisatie van het GLU kan leren en kan sturen:

1. Factoren die niet zijn te veranderen
Dit zijn factoren die zijn gelegen in de kern van de docent, die van primair belang lijken om op te sturen, zoals: de krachten en deugden, de betrokkenheid, de identiteit en de overtuigingen van docenten. Daarnaast lijkt het er op dat ook talenten, levens- en praktijkervaringen een belangrijke rol spelen. Dit is van belang voor de intrinsieke motivatie en drive van docenten.

2. Factoren die zijn te veranderen
Veranderbare factoren zijn voor docenten onderwijsteams en de organisatie belangrijke stuurmiddelen. Deze factoren zijn gelegen in de docent, die middels de les, waarbinnen de inhoud en de studenten een belangrijke rol spelen, de kwaliteit van het onderwijs bepaald. Enerzijds zijn er factoren die de docent en misschien ook wel de organisatie, kunnen leren of adapteren. Anderzijds zijn er factoren die vooral te maken hebben met tijds- en omgevingsfactoren die de organisatie vanuit school- en/of teamniveau kan faciliteren of organiseren.

a) Factoren die zijn te adapteren en/of aan te leren
Deze factoren zijn vooral gelegen binnen de werkwijzen, de handelingen of het gedrag van docenten.

Werkwijzen gelegen in:
doel, structuur, inhoud, werkvorm en opbouw van de les
de juiste mix van kennis, vaardigheden, theorie, fun en uitdagingen zodanig dat het ruimte laat voor de eigenheid van de student.
het opstarten en in beweging zetten van de les: visuele voorbeelden en instructie
het meten van de opbrengst

Handelingen of gedrag gelegen in:
de voorbereiding en instructie bij van het opstarten van de les
de feedback: oriënterend, activerend optreden, rondlopen, in beweging blijven
proactief handelen: ingrijpen, anticiperen
de ruimte die studenten wordt geboden voor eigen invulling, tempo en verantwoordelijkheid, het uitgaan van voorkennis en leerbehoefte
het nastreven van een doel: kennis, theorie, vaardigheden, resultaat en de opbrengst van de les
het zoeken naar eigen uitdagingen binnen de les: vers houden van kennis en vaardigheden

b) Factoren die zijn te faciliteren
Dit zijn factoren die zijn gelegen in de omgeving van de les, zoals: lokaal, ICT en apparatuur.

c) Factoren die zijn te organiseren
Dit zijn factoren die zijn gelegen in de organisatie rond de les, zoals: de activiteiten van de lessen in relatie tot het lokaal, in relatie tot elkaar, het rooster en de tijd.

De thematisering van de factoren binnen de resultaten van de interviews heeft er toe geleid dat de eigenschappen die van de best practice factoren kunnen worden benoemd, nu kunnen worden herleid op welke belanghebbenden uit de organisatie ze betrekking hebben. Aldus kan de school op alle niveaus van haar organisatie de onderwijskwaliteit aansturen.

Akkerman, S. (2012). Yrjö Engestrom, Activity Theory. In M. Ruijters & R.J. Simons. Canon van het leren. (p.p. 51-76), Deventer: Kluwer.
Csikszentmihalyi, M. (1999). Flow: Psychologie van de optimale ervaring. Amsterdam: Boom.
Korthagen, F., Vasalos, A. (2007). Kwaliteit van binnenuit als sleutel voor professionele ontwikkeling. VELON-Tijdschrift, 28(1), 17-23.
Masselink, R., van den Nieuwenhof, R., de Jong, J.C. & van Iren, A. (2008). Waarderend organiseren. Appreciative Inquiry. Co-creatie van duurzame verandering. Nieuwerkerk aan den IJssel: Gelling Publishing.
Peterson, C., Seligman, M. E. P. (2004). Character Strengths and Virtues. Oxford: Oxford University Press.
Pink, Daniel H. (2010). Drive – The Surprising Truth about what motivates us. New York: Penguin Group
Robinson, K. & Aronica, L. (2009). The Element: How Finding Your Passion Changes Everything. London: Penguin Group

Computational fluid dynamics (CFD) calculations of pump sumps are troublesome due to the nature of the flow. Pump sump flow is turbulent and unsteady, and pump sump dimensions are large compared to diameter of vortices occurring near the sump walls or in the pump column. Therefore, to capture the general and important phenomena of the flow, the computational grid should be fine enough at certain areas of the sump. Combined with unsteady calculations, this usually results in computationally expensive cases. The decision for a suitable turbulent model plays an important role in adding or reducing the computational costs. The present study first compares some different turbulent models on a fine computational grid to the published experimental model. The intention of the present work is to get an answer whether the Unsteady Reynolds Averaged Navier-Stokes (URANS) model really fails in predictions of vortex modeling, since the usage of Large Eddy Simulation (LES) model for industrial cases would represent huge computational power demands. In the second part of the paper a real case pump sump is analyzed.

Numerical prediction of an efficiency of a 6-blade Kaplan turbine is presented. At first, the results of steady state analysis performed by different turbulence models for different operating regimes are compared to the measurements. For small and optimal angles of runner blades the efficiency was quite accurately predicted, but for maximal blade angle the discrepancy between calculated and measured values was quite large. By transient analysis, especially when the Scale Adaptive Simulation Shear Stress Transport (SAS SST) model with zonal Large Eddy Simulation (ZLES) in the draft tube was used, the efficiency was significantly improved. The improvement was at all operating points, but it was the largest for maximal discharge. The reason was better flow simulation in the draft tube. Details about turbulent structure in the draft tube obtained by SST, SAS SST and SAS SST with ZLES are illustrated in order to explain the reasons for differences in flow energy losses obtained by different turbulence models.

Large-eddy simulation (LES) is conducted to investigate the flow around a simplified ICE2 train under side wind conditions at 30 degrees yaw angle. The Reynolds number based on the height of the train and the free stream velocity is 2 x 10(5). Two computations on two different meshes with different numbers of nodes are made to check the effect of the mesh resolution on the results. The fine and the coarse meshes give similar results meaning that the results are mesh independent. The results are also verified against available experimental data. Good agreement is obtained between the LES results and the experimental data. The LES results show that two flow regimes exist in the wake. The first flow regime consists of steady vortex lines in the upper part of the wake flow. It changes into unsteady shedding after a distance of about five train heights from their onset on the surface of the train. The second flow regime is the unsteady movement of the lower part of the wake vortices. They attach and detach from the surface of the train in a regular fashion. The time-averaged flow and the instantaneous flow around the ICE2 train at 30 degrees yaw angle are explored.

Keywords: ICE2 train; flow structures; side wind; LES; train aerodynamics

A popular functional form for modeling the consumption block of a computable general equilibrium model (CGE) is the Linear Expenditure System (LES) for which the Engel curves are straight lines. The LES does not allow for the existence of inferior commodities, for elastic demand and does not allow gross substitution. To calibrate the parameters outside information on income elasticities and the Frisch parameter is needed. In this paper we propose to use the Indirect Addilog System (IAS) that allows for non-straight Engel curves, inferior commodities, elastic demand and gross substitution, and for which the outside data requirement is the same as for LES. The income elasticities of the IAS can easily be estimated from a budget survey. In the empirical part we estimate the income elasticities of the IAS from the 1998 Palestinian Expenditure and Consumption Survey (PECS). We replace the LES consumption block with a priori fixed income elasticities of the CGE model, that we previously c...

Recent case studies on the precursor signatures of equatorial spread-F (ESF) have shown a one-to-one correspondence between the large-scale wave structures (LSWS) and ESF development at equatorial latitude. In this study, the LSWS and the onset and development of the ESF are investigated over Sanya (18°N, 109°E), a station located at 13° north of the magnetic equator, during both geomagnetic quiet and disturbed conditions in September–October 2011. High-time-resolution ionograms from Digisonde Portable Sounder (DPS-4D) provided the satellite trace measurements that were used to indicate the occurrence of the LSWS. The development of local ESF activity was identified using GPS scintillation and VHF coherent radar echo measurements from the same site, together with the range type spread-F (RSF) in ionograms. Additionally, the Sanya VHF radar five-beam scanning measurements in east–west direction were used to characterize the longitudinal difference in establishing the initial conditions for ESF development. Correlative studies between the LSWS and ESF activities during the observational period offer consolidated evidence that the LSWS is a necessary precursor for the ESF development. It is shown that the LSWS and ESF have nearly a one-to-one relationship when the F layer undergoes an abrupt post-sunset rise (PSSR), revealing that the magnitude of the pre-reversal enhancement in zonal electric field (PRE) that elevates the F layer to a high enough altitude is an important parameter controlling the generation of post-sunset ESF. However, in the absence of the PSSR, the ESF and GPS scintillation did not always occur following the appearance of LSWS. Sometimes the LSWS events preceded the generation of bottom type spread-F (BSF) that did not develop vertically into ESF and radar plumes. This result may indicate that under inexpressive, weak, or even moderate PRE conditions, the appearance of the LSWS alone may not be sufficient to produce the post-sunset F region irregularities responsible for ionospheric scintillations. More factors, other than the LSWS, could play crucial roles favoring the growth of ESF instabilities responsible for ionospheric scintillations.

We consider the effects of chordwise flexibility on the aerodynamic performance of flapping wings using numerical simulation. The two-dimensional Navier–Stokes equations are solved using a Fourier pseudo-spectral method with no-slip boundary conditions imposed by the volume penalization method. The flexible wing is modelled with a non-linear beam equation. Our numerical simulations of heaving plates show that the maximum thrust is achieved at a stroke frequency lower than resonant, which is in agreement with experiments. The oscillatory part of the force only increases in amplitude when the frequency increases. We also consider aerodynamic interactions between two heaving foils.

This article is focused on the choice of a suitable turbulence model for simulations of an industrial pump's intake, from the perspective of accuracy and, partially, also the CPU time. Twelve steady-state and transient simulations were made on a fine computational mesh, using turbulence models such as: the shear stress transport (SST), the scale-adaptive simulation (SAS), the Reynolds stress model, the explicit algebraic Reynolds-stress model, the detached eddy simulation and the large eddy simulation (LES). The curvature-correction (CC) option was assessed for the SST and SAS turbulence models. The results were compared with the LES and with published experimental results. Although all the models could predict the main floor vortex, there were still some substantial differences. It can be able to conclude that it is better to use either the SST-CC turbulence model, due to its low-computational resources and far better results than the SST model, or the SAS-CC turbulence model, since its predictions are quite similar to the LES results. In the final step, good agreement with experimental results was shown for a longer simulation with the SAS-CC turbulence model.

We present a newly developed unstructured high order h/p Discontinuous Galerkin Finite Element solver for the computation of tidal turbine hydrodynamics. The solver allows for accurate flow solutions of the two dimensional incompressible Navier-Stokes equations on hybrid meshes (triangular-quadrilateral) with rotating geometries using sliding mesh interfaces. High accuracy is obtained by enabling arbitrary polynomial orders within each mesh element allowing mesh size refinement (h-refinement) and/or polynomial enrichment (p-refinement).

The solver is validated for static NACA0012 and NACA0015airfoil flows for a range of Reynolds numbers including laminar and turbulent regimes. Results for a typical cross-flow tidal turbine are also included for laminar flows and the resulting flowphysics explored. Wake-blade interference effects are analysed for single and three bladed turbines. Results for a three bladed turbine under ducted conditions (tidal fence concept) are also reported.We show that the solver provides accurate results and is thus a valuable tool to accurately predict flows through cross-flow tidal turbine devices and to explore their hydrodynamics.

The present work develops a low cost numerical method for the solution of nonpremixed piloted methane jet flames. This method is based on the mixture fraction for fluid flow and on unsteady flamelet models, combined with the presumed probability density function, for the chemistry. Numerical tests, for the governing equations discretized by the finite difference and solved by the Gauss-Seidel scheme, were carried out for turbulent, nonpremixed, nonreacting propane-jet flow and for confined Sandia C and D flames for reasonable values of gaseous hydrocarbon chemistry. The methodology, developed for low Mach number flows and based on a density approximation, allows to decrease considerably the computational time while obtaining results which contributes to a better understanding of the complexity involved in the numerical solution of piloted methane jet diffusion flames.

Keywords: Sandia flames; low Mach number; finite difference; flamelet; LES

This paper investigates the unsteady, near wake of a circular cylinder in cross flow at a Reynolds number of 5.5 x 10(3) using Large Eddy Simulation (LES). The near and intermediate wake velocity fields and unsteady aerodynamic forces compare well against available experimental data. Flow visualisation results show the presence of intermittent Kelvin Helmholtz (KH) instabilities in the very near wake. An empirical relation is presented for the spanwise length scales associated with KH instability that compares favourably with LES data. A wavelet analysis technique is used to investigate the frequency content of near wake. This analysis shows the existence of vortex pairing and breakdown in the near wake, providing further evidence that the near wake shear layer behaves in a similar manner to a mixing layer.

Keywords: LES; shear layer instability; large eddy simulation; cylinder near wake

This article is focused on the choice of a suitable turbulence model for simulations of an industrial pump's intake, from the perspective of accuracy and, partially, also the CPU time. Twelve steady-state and transient simulations were made on a fine computational mesh, using turbulence models such as: the shear stress transport (SST), the scale-adaptive simulation (SAS), the Reynolds stress model, the explicit algebraic Reynolds-stress model, the detached eddy simulation and the large eddy simulation (LES). The curvature-correction (CC) option was assessed for the SST and SAS turbulence models. The results were compared with the LES and with published experimental results. Although all the models could predict the main floor vortex, there were still some substantial differences. It can be able to conclude that it is better to use either the SST-CC turbulence model, due to its low-computational resources and far better results than the SST model, or the SAS-CC turbulence model, ...

Resumen: Investigaciones sobre la cavitación tienen una gran importancia económica en el campo de la maquinaria hidráulica. Durante más de 40 años, métodos de mecánica computacional de fluidos han sido para entender estos fenómenos y ayudar a mejorar los diseños de maquinarias y equipos, como el caso de bombas y turbinas hidráulicas. Sin embargo, la cavitación aparece en flujos con números de Reynolds grandes, por lo cual, los modelos tradicionales de turbulencia Reynolds-averaged Navier-Stokes (RANS) k − y k − ω no son capaces de capturar el fenómeno de burbujas en movimiento. Por lo cual, la presente investigación usa el modelo de turbulencia Large Eddy Simulation (LES) con métodos implícitos (ILES) y explícitos (ELES), para simular la cavitación alrededor de un perfil plano-convexo. La simulación CFD ha sido llevada a cabo usando el programa de código abierto OpenFOAM y lenguaje python para el procesamiento de datos. La investigación indica que ELES y ILES porporcionan resultados similares a resultados experimentales obtenidos en el túnel de cavitación de la École Polytechnique Fédérale de Lausanne (EPFL).

Abstract: Investigations of attached partial cavitation are important because to prevent damages in hydrulic machinery and to reduce the costs. As expected computational fluid dynamics (CFD) methods have been developed for more than 40 years to understand this phenomenon and to improve the machinery designs, as pumps and hydraulic turbines. However, cavitation appears at high Reynolds numbers, so that, the traditional turbulence models Reynolds-averaged Navier-Stokes (RANS) k − and k − ω are not able to capture the bubbles motion. Therefore, large eddy simulation with implicit (ILES) and explicit (ELES) turbulence methods have been used to capture and study partial cavitation around a plane-convex hydrofoil. The CFD simulation has been carried out by the free open source software OpenFOAM and python language for data analysis. The research shows that ELES and ILES give results similar to experiments from the cavitation tunnel of the École Polytechnique Fédérale de Lausanne (EPFL).

Raziskali smo fizikalne lastnosti hrastovega lesa (Quercus sp.), pri katerem je od poseka minilo od 4 do 512 let in smo ga razdelili v stoletne starostne skupine 100-600. Mlajši les smo pridobili ob poseku dreves, starejši les pa iz zgodovinskih konstrukcij v Sloveniji. Izbrani les smo najprej dendrokronološko datirali, izdelali normirane vzorce za analize ter določili gostoto, barvo, dimenzijsko stabilnost in sorpcijske lastnosti. Vizualno in v CIELab barvnem prostoru smo ugotovili, da je barva jedrovine s starostjo postala temnejša. Pri starem hrastovem lesu smo ugotovili tudi manjšo higroskopnost in izboljšano dimenzijsko stabilnost, zlasti v tangencialni smeri, ter manjšo prečno krčitveno anizotropijo.Gostota hrastovega lesa se s staranjem ni spremenila, odvisna pa je bila od širine branik (naraščala je z večanjem deleža kasnega lesa). Rezultati nakazujejo, da na dimenzijsko stabilnost in higroskopnost poleg procesov staranja ver-jetno vpliva tudi mesto vgradnje in klimatska nih...

"This paper aims at making an assessment of the performance of the large eddy simulation (LES) method in simulating the complex vortical flow in a Francis hydraulic turbine. Firstly the principle of the LES method is presented. Then, three-dimensional turbulent flow of the Francis turbine under selected condition is simulated using the LES method with the Smagorinsky-Lilly model. In the hydraulic turbine, pressure distribution, vortex structures and other flow information are captured, from which the low pressure area beside the suction side of the blade and vortex structure in the draft tube can be seen clearly. Compared with the results from both experiments and simulations by the Reynolds average Navier-Stokes (RANS) method with the k-ε turbulent model, the LES results are proven to be more accurate in predicting the overall performance and interior flow characteristics of Francis hydraulic turbine. This work attempts to apply the LES method to simulate the flow field in the flow passages of the whole runner, cone, elbow and diffuser, thereby obtaining the instantaneous characteristics of hydroturbine, including the pressure distribution, vorticity field and streamlines.

Keywords: large eddy simulation (LES); assessment; turbulent flow field; Francis hydraulic turbine"

This thesis investigates the aerodynamic and aeroacoustic prediction of vertical axis wind turbines, using computational fluid dynamics simulations. Noise pollution from wind turbines is one of the disadvantages of wind energy, calling for strategies to reduce noise levels. Yet for vertical axis wind turbines in particular, there is insufficient knowledge of how to identify sound sources and mitigate the sound level. The aim of this study is to predict aerodynamic noise, using large eddy simulation and acoustic analogy, so as to better understand the mechanism of sound generation for vertical axis wind turbines. First, the prediction method is validated for a static single blade in stall. This model is able to capture the dominant frequency, but it does not well reproduce the broadband characteristics. Next, the aerodynamic behavior of the 12 kW H-rotor vertical axis wind turbine is studied, whereby the focus is on the importance of properly modeling the strut influence for an accur...

The present- day Large Eddy Simulation models based on the Smagorinsky assumption and the drawbacks of the dynamic calcula-tion of the closure coefficient for the generalised subgrid scale turbulent stress tensor are presented. The relations between numerical scheme conservation property of mass, momentum and kinetic energy and the drawbacks of the dynamic Smagorinsky- type turbulence models are shown. A new turbulence model is proposed. The proposed model: a) is able to take into account the anisotropy of the turbulence; b) remove any balance assumption between the production and dissipation of sub-grid scale turbulent kinetic energy; c) is able to eliminate the numerical effects produced by the non conservation a priori of the resolved kinetic energy. New closure relations for the unknown terms of the subgrid scale viscous dissipation balance equation are proposed. The filtered momentum equations are solved by using a sixth order finite difference scheme. The proposed model is tes...

MVG (micro vortex generator) is a potentially new device which can alleviate or overcome the adverse effects of SBLI (Shockboundary layer interaction) and improve the “health” of the boundary layer. In this paper, the SBLI in a ramp flow with MVG under
different inflow conditions is investigated by LES (large eddy simulation). Three turbulent inflows with different boundary layer
thickness are generated based on turbulent profiles obtained from DNS (Direct numerical simulation) of transition. The numerical
results show that the interaction between ring-like vortices generated by MVG and the ramp shock is influenced by these different
inflow conditions. With lower boundary layer thickness, the ring-like vortices are less distorted and thus more stronger when they
travel to the ramp corner. The more regular and stronger ring-like vortices have more capability to eliminate or distort the strong
ramp shock wave. Moreover, it confirms that ring-like vortices generated by MVG, and not the lower turbulent boundary layer, is
dominant in flow separation reduction

Page 1. Quels découpages territoriaux pour la gestion de l'environnement ? Thierry Joliveau et Olivier Barge CRENAM/CNRS UMR 5600. Entretiens Jacques Cartier : décembre 1997. Lyon : les découpages du territoire Page 2. Les vicissitudes d'un zonage sur des bases ...

Abstract The paper presents a comparative analysis of recent simulations, conducted in the framework of a French-German collaboration on LES of Complex Flows, for the so-called Ahmed body at Reynolds number 768000 and slant angle 25. It provides a juxtaposition of ...

"One of the unresolved problems is the unsteady inlet boundary condition in current Computational Fluid Dynamics (CFD) simulations or Computational Wind Engineering (CWE). It is known that the inlet boundary condition of the current CFD or CWE simulations is always specified as a steady one, which ignores the turbulence effect from the upwind direction. In this paper a numerical procedure of inflow turbulence based on the digital filter technique (Autoregressive Moving Average (ARMA) model) is presented and validated to realize the inflow turbulence and then this approach is adopted to investigate the flow characteristics around a square cylinder at zero angle of incidence based on different Large Eddy Simulation (LES) models.

Keywords: LES, Inflow turbulence, ARMA, CWE"

In this paper we present the modelled results of turbulence, scalar mixing and intermittency for three different basic fluid dynamical problems using large eddy simulation (LES). The modelled problems are a turbulent round jet, a bluff body stabilised jet, and a bluff body stabilised swirl jet in a co-flow environment. Both instantaneous and time averaged results along with the probability density functions (pdf) and intermittency of velocity and passive scalar are presented. Simulations well captured the flow features of jet, bluff body stabilised jet and bluff body stabilised swirl jet. The instantaneous and time averaged data show the differences in turbulence and mixing and also an improvement of mixing in the presence of a bluff body and swirl. The addition of bluff body and swirl affect the structure of pdfs for both velocity and passive scalar at different axial and radial locations. The radial variation of intermittency at locations close to the centreline indicates turbulent to non-turbulent phenomena with respect to bluff body and swirl at both upstream and downstream recirculation regions.

Keywords: jet; bluff body; swirl; mixing; intermittency; LES