• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.200-202
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• 2003

In this paper, Gauss filter function is used to filter the N-S equation and the subgrid-scale Reynold stresses model is introduced to deduce the practical form of LES equation for 2-D case for flow calculation of hydraulic machine. Then the LES equation and its discrete form in computational field are obtained in the body-fitted coordinate system and the numerical calculation program is built. The incompressible turbulent flow in double-flow-conduits-sewage pump impeller is computed by using the abovementioned program, and then the distribution rules of velocity and pressure in flow field are obtained. Based on this, the designs of double-flow-conduits-sewage pump impeller are optimized.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.222-227
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• 2007

Formation of freak waves is studied in deep water from transient wave packets propagating on current. Those waves are obtained by means of dispersive focusing. This process is investigated by solving both linear and nonlinear equations. The role of nonlinearity is emphasized in this interaction.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.242-245
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• 2005

The rotating flow in the space between co-rotating disks is of considerable importance in information storage systems. Hard disk drivers(HDD) in computer are used extensively as data storage capacity. The trend in the computer industry to produce smaller disk drives rotating at higher speed requires an improved understanding of fluid motion in the space between disks. In this study, we have tried LES model for inner-disk flowfield to investigate the flow disturbance and the flow structure driven by co-rotating disks. The boundary pattern between inner region and outer region obtained lobe-shape structure clearly and its number has been validated on experimental data by our previous study. We obtain the spectra of velocity and pressure components with several frequencies. We revealed there are two kinds of disturbances, one is global wave propagation and another is local wave propagation on Ekman boundary layer.

• Wind and Structures
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• v.7 no.1
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• pp.29-40
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• 2004

This study has focused on aerodynamics for a wind-resistance design about the single and tandem box girder sections to realize a super-long span bridge in the near future. Three-dimensional static analysis of flows around the fundamental single and tandem box girder sections with fairing is carried out by means of the IBTD/FS finite element technique with LES turbulence model. As the results of the analysis, computations have verified aerodynamic characteristics of both sections by the histories of aerodynamic forces, the separation and reattachment flow patterns and the surface pressure distributions. The relationship between the section shapes and the aerodynamic characteristics is also investigated in both sections. And the mechanism about the generation of fluctuating aerodynamic forces is discussed.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.152-157
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• 2003

As computer capacity has been progressed continuously, the studies of the flow characteristics have been performing by the numerical methods actively. Recent numerical simulation has a tendency to require the higher-order accuracy in time, as well as in space. This tendency is more true in LES and acoustic noise simulation. In this study, 3-dimensional unsteady Incompressible Navier-Stokes equation was solved by numerical method using the fractional step method with the fourth order compact pade scheme to achieve high accuracy To validate the present code and algorithm, 3D flow-field around a cylinder was simulated. The drag coefficient and lift coefficient were computed and, then, compared with experiment. The present code will be tailored to LES simulation for more accurate turbulent flow analysis.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.123-126
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• 2013

Combustor development requires high fidelity simulation capable of predicting recirculation zone (RZ), temperature field, and pollutant emission. Swirling flow is widely used in combustor for its benefits in efficient mixing and flame stabilization by RZ. Large eddy simulation (LES) is used to calculate swirling flow in an expanding pipe [1], and shows higher accuracy than RANS. Reactive flow modeling using LES and flamelet model is validated with experiments by Barlow et al. [4] and Masri et al. [3]. Finally, heat transfer simulation of Samsung Techwin's combustor liner is presented.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.1
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• pp.98-108
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• 2004

This study concerns a large eddy simulation (LES) of turbulent flow around a bluff body inside a sudden expansion cylindrical chamber, a configuration which resembles a premixed gas turbine combustor The simulation code is constructed by using the general coordinate system based on the physical contravariant velocity components. The Smagorinsky model is employed and the calculated Reynolds number is 5,000 based on the bulk velocity and the diameter of the inlet pipe. The combined grid technique and cylindrical grid are tested in the numerical simulation with complex geometry. The predicted turbulent statistics are evaluated by comparing with LDV measurement data. The numerical flow visualizations depict the behavior of turbulent mixing process behind the flame holder.

• Journal of Korean Theatre Studies Association
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• no.40
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• pp.239-275
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• 2010

Cette ${\acute{e}}tude$ a pour but de proposer une $m{\acute{e}}thodologie$ de critique avec la $s{\acute{e}}miotique$ ouverte. La critique de $th{\acute{e}}{\hat{a}}tre$ commence ${\grave{a}}$ lire le $th{\acute{e}}{\hat{a}}tre$, l'analyse et juge son valeur. Il arrive souvent qu'on juge avec intutition. On dit que c'est une critique d'impressionnisme. Cette critique est subjective, mais pas objective. La $s{\acute{e}}miotique$ de Saussure offre la $m{\acute{e}}thodologie$ scientifique ${\grave{a}}$ la critique. A $c{\hat{o}}t{\acute{e}}$ de la critique d'impressionnisme qui est subjective, la $s{\acute{e}}miotique$ peut expliciter la raison objective. On ${\acute{e}}tait$ admiratif devant sa scientisme, pourtant $apr{\grave{e}}s$ quoi on critique sa non-$subjectivit{\acute{e}}$ et sa non-$historicit{\acute{e}}$. Dans l'opposition de $l^{\prime}objectivit{\acute{e}}$ et de la $subjectivit{\acute{e}}$, on tente de rechercher un model $int{\acute{e}}gr{\acute{e}}$ dialectiquement entre l'impressionisme(subjective) et la scientisme(objective). Pour cela, on doit aux Ecrits de linguistique $g{\acute{e}}n{\acute{e}}rale$ ($publi{\acute{e}}$ en 2002 chez Gallimard). Ces Ecrits nous aident ${\grave{a}}$ amener la $s{\acute{e}}miotique$ $ferm{\acute{e}}e$ sur la $s{\acute{e}}miotique$ ouverte et ${\grave{a}}$ $red{\acute{e}}couvrir$ la $pens{\acute{e}}e$ de Saussure. Ils nous font ouvrir un nouveau champ de recherche pour la $s{\acute{e}}miotique$ ouverte. L'essentiel de la $th{\acute{e}}orie$ saussurienne du signe $d{\acute{e}}pend$ de l'arbitraire et du circulaire du signe. On $red{\acute{e}}couvre$ la notion ${\acute{e}}largie$ du signe, dans Ecrits de linguistique $g{\acute{e}}n{\acute{e}}rale$, contre le courant majeur de linguistique et de structuralisme. Cette notion s'y focalise, ${\grave{a}}$ la valeur, ${\grave{a}}$ la $relativit{\acute{e}}$, ${\grave{a}}$ la $diff{\acute{e}}rence$ et au $syst{\grave{e}}me$. Avec elle, on tente d'adopter la $s{\acute{e}}miotique$ ouverte pour rechercher une $m{\acute{e}}thodologie$ de critique qui se veut objective et ${\grave{a}}$ la fois subjective. Il s'agit d'une difficile combinaison de l'impressionisme et de la scienticisme. Pour cela, la $m{\acute{e}}thodologie$ se $d{\acute{e}}veloppera$ en trois ${\acute{e}}tapes$. $1{\grave{e}}re$ ${\acute{e}}tape$: c'est lire le $th{\acute{e}}{\hat{a}}tre$ comme un signe total pour 1er jugement d'impressionnisme. $2{\grave{e}}me$ ${\acute{e}}tape$: c'est retrouver sa structure invisible dans la $relativit{\acute{e}}$ des signes. $3{\grave{e}}me$ ${\acute{e}}tape$: c'est juger, dans leur $relativit{\acute{e}}$, comment les $d{\acute{e}}tails$ de signes se fonctionnent. C'est lire les $d{\acute{e}}tails$ de signes et puis $r{\acute{e}}affirmer$ le jugement en $1{\grave{e}}re$ ${\acute{e}}tape$. Selon les $derni{\grave{e}}res$ deux ${\acute{e}}tapes$, on pourra comparer le premier jugement (impressif) et le dernier jugement (objectif), et enfin s'assumer comme critique. Selon la $m{\acute{e}}thodologie$ $propos{\acute{e}}e$, on pratique la critique sur ${\acute{e}}crit$ par Jean Genet, et mise en $sc{\grave{e}}ne$ par Lee Youn-Taek et par Park Jung-Hee. Pour la critique intertextuelle, on la fera en comparant les deux spectacles avec la $pi{\grave{e}}ce$ de Jean Genet. $D^{\prime}apr{\grave{e}}s$ la comparaison, Lee Youn-Taek met en $sc{\grave{e}}ne$ avec $fid{\acute{e}}lit{\acute{e}}$ la structre et les signes de $d{\acute{e}}tail$ de l'auteur, Park Jung-Hee change sa structre et ses signes pour mettre en $sc{\grave{e}}ne$ la $pi{\grave{e}}ce$ de Genet. Ils se $diff{\grave{e}}rent$ l'un et l'autre: Lee incite le discours de la classe sociale dans le spectacle, et Park y incite le discours du $d{\acute{e}}sir$. La $diff{\acute{e}}rence$ des signes dans la $relativit{\acute{e}}$ apporte la $diff{\acute{e}}rence$ de la signification de discours $th{\acute{e}}{\hat{a}}tral$, et enfin se font changer les significations de deux spectacles.

• Fire Science and Engineering
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• v.26 no.1
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• pp.31-37
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• 2012

This study is intended to present a computational thermal model for a residential building. As the Performance Based Design is more popular, fire-intensity and fire-load have turned out to be very important factors for building design and can be predicted through some computational work. To predict and estimate the fire properties of a residential fire, we made some numerical models of combustibles and residential building. In a bid to validate the estimate values, computational analysis results from numerical models were compared with real fire tests. For computational analysis, the Fire Dynamics Simulator (FDS) was used with Large Eddy Simulation (LES) model for turbulence. Consequently, fire-intensity was well predicted and flash-over of rooms were successfully estimated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.2
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• pp.99-110
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• 2010

The DES analysis of strong compressibility flow, LES mode is intentionally performed in boundary layer with the conventional empirical constant $C_{DES}$ value of 0.65. In this study, an expression is suggested to determine the $C_{DES}$ value dynamically by using a distribution function of the ratio of turbulence length scale and wall distance which is used in S-A DDES model for RANS mode protection. The application of the dynamic $C_{DES}$ presents better prediction than previous results those used constant but different $C_{DES}$ values.