bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of sharp gas–liquid interface using VOF method and adaptive grid local refinement around the interface
Authors: Theodorakakos A. , Bergeles G. 
Published: April 2004

AbstractThe volume of fluid (VOF) method is used to perform two‐phase simulations (gas–liquid). The governing Navier–Stokes conservation equations of the flow field are numerically solved on two‐dimensional axisymmetric or three‐dimensional unstructured grids, using Cartesian velocity components, following the finite volume approximation and a pressure correction method. A new method of adaptive grid local refinement is developed in order to enhance the accuracy of the predictions, to capture the sharp gas–liquid interface and to speed up the calculations. Results are compared with experimental measurements in order to assess the efficiency of the method. Copyright © 2004 John Wiley & Sons, Ltd.
An aeroacoustic hybrid approach for non‐isothermal flows at low Mach number
Authors: Golanski F. , Prax C. , Lamballais E. , Fortuné V. , Valière J.‐C. 
Published: April 2004

AbstractThis paper presents an aeroacoustic hybrid technique for the study of non‐isothermal flows at low Mach number. The flow dynamics and the acoustic production and propagation are computed separately. The fully compressible Navier–Stokes equations are modified through an expansion of the physical quantities using a low Mach number approximation. Compressibility effects are thus removed in the CFD while inhomogeneities of the flow related to heat transfer are preserved. One advantage is a reduction of the time step constraint. Another advantage is that the Mach number does not appear explicitly and a simple rescaling allows a study over a relatively wide band of subsonic Mach number flows with a single dynamic simulation.Compatible acoustic source terms for LEE based propagation have been defined and the procedure is implemented in the case of a temporal mixing layer. Compressible simulations for Mach numbers of 0.2, 0.3 and 0.4 are compared with the numerical results obtained using the proposed method. Very good agreement is obtained even at relatively high subsonic Mach number demonstrating the efficiency of the proposed technique. Copyright © 2004 John Wiley & Sons, Ltd.
Finite‐volume‐type VOF method on dynamically adaptive quadtree grids
Authors: Wang J. P. , Borthwick A. G. L. , Taylor R. Eatock 
Published: April 2004

AbstractThis paper describes a finite‐volume volume‐of‐fluid (VOF) method for simulating viscous free surface flows on dynamically adaptive quadtree grids. The scheme is computationally efficient in that it provides relatively fine grid resolution at the gas–liquid interface and coarse grid density in regions where flow variable gradients are small. Special interpolations are used to ensure volume flux conservation where differently sized neighbour cells occur. The numerical model is validated for advection of dyed fluid in unidirectional and rotating flows, and for two‐dimensional viscous sloshing in a rectangular tank. Copyright © 2004 John Wiley & Sons, Ltd.
Linearized and rational approximation method for solving non‐linear Burgers' equation
Authors: Wu Yun , Wu Xionghua 
Published: April 2004

AbstractA new numerical method called linearized and rational approximation method is presented to solve non‐linear evolution equations. The utility of the method is demonstrated for the case of differentiation of functions involving steep gradients. The solution of Burgers' equation is presented to illustrate the effectiveness of the technique for the solution of non‐linear evolution equations exhibiting nearly discontinuous solutions. Copyright © 2004 John Wiley & Sons, Ltd.
A non‐linear coupled fluid–structure aeroelastic analysis of a slender bridge deck
Authors: Lopes A. V. , Cunha Alvaro , Simões L. M. C. 
Published: April 2004

AbstractThis paper presents a new numerical methodology for the integral aeroelastic instability analysis of slender structures, based on the appropriate conjugation of an algorithm for dynamic and geometrically non‐linear analysis of structures based on the finite element method with another algorithm of computational fluid dynamics (Finite volume method). It is considered a viscous incompressible unsteady turbulent bidimensional air flow solved on a structured control volume mesh. The computer code developed on the basis of this methodology is applied to the aeroelastic study of a simply supported slender bridge deck in order to find out the critical wind velocity leading to instability. Some of the most significant results associated with the analysis of the corresponding aeroelastic behaviour are presented. Copyright 2004 John Wiley & Sons, Ltd.
A combined analytical–numerical method for treating corner singularities in viscous flow predictions
Authors: Shi J.‐M. , Breuer M. , Durst F. 
Published: April 2004

AbstractA combined analytical–numerical method based on a matching asymptotic algorithm is proposed for treating angular (sharp corner or wedge) singularities in the numerical solution of the Navier–Stokes equations. We adopt an asymptotic solution for the local flow around the angular points based on the Stokes flow approximation and a numerical solution for the global flow outside the singular regions using a finite‐volume method. The coefficients involved in the analytical solution are iteratively updated by matching both solutions in a small region where the Stokes flow approximation holds. Moreover, an error analysis is derived for this method, which serves as a guideline for the practical implementation. The present method is applied to treat the leading‐edge singularity of a semi‐infinite plate. The effect of various influencing factors related to the implementation are evaluated with the help of numerical experiments. The investigation showed that the accuracy of the numerical solution for the flow around the leading edge can be significantly improved with the present method. The results of the numerical experiments support the error analysis and show the desired properties of the new algorithm, i.e. accuracy, robustness and efficiency. Based on the numerical results for the leading‐edge singularity, the validity of various classical approximate models for the flow, such as the Stokes approximation, the inviscid flow model and the boundary layer theory of varying orders are examined. Although the methodology proposed was evaluated for the leading‐edge problem, it is generally applicable to all kinds of angular singularities and all kinds of finite‐discretization methods. Copyright © 2004 John Wiley & Sons, Ltd.
Large eddy simulation of flow and scalar transport in a round jet
Authors: Suto Hitoshi , Matsubara Koji , Kobayashi Mutsuo , Kaneko Yoshiaki 
Published: April 2004

AbstractLarge eddy simulation (LES) was performed for a spatially developing round jet and its scalar transport at four steps of Reynolds number set between 1200 and 1,000,000. A simulated domain, which extends 30 times the nozzle diameter, includes initial, transitional, and established stage of jet. A modified version of convection outflow condition was proposed in order to diminish the effect of a downstream boundary. Tested were two kinds of subgrid scale (SOS) models: a Smagorinsky model (SM) and a dynamic Smagorinsky model (DSM). In the former model, parameters are kept at empirically deduced constants, while in the latter, they are calculated using different levels of space filtering. Data analysis based on the decay law of jet clearly presented the performance of SGS models. Simulated results by SM and DSM compared favorably with existing measurements of jet and its scalar transport. However, the quantitative accuracy of DSM was better than that of SM at a transitional stage of flow field. Computed parameters by DSM, coefficient for SGS stresses, CR and SGS eddy diffusivity ratio, ΓSGS, were not far from empirical constants of SM. Optimization of the model coefficient was suggested in DSM so that coefficient CR was nearly equal in the established stage of jet but it was reduced in low turbulence close to the jet nozzle. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(3): 175–188, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20001
Reverse computation of forced convection heat transfer for optimal control of thermal boundary conditions
Authors: Momose Kazunari , Abe Kouhei , Kimoto Hideo 
Published: April 2004

AbstractA reverse computation based on adjoint formulation of forced convection heat transfer is proposed to obtain the optimal thermal boundary conditions for heat transfer characteristics; for example, a total heat transfer rate or a temperature at a specific location. In the reverse analysis via adjoint formulation, the heat flow is reversed in both time and space. Thus, using the numerical solution of the adjoint problem, we can inversely predict the boundary condition effects on the heat transfer characteristics. As a result, we can obtain the optimal thermal boundary conditions in both time and space to control the heat transfer at any given time. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(3): 161–174, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20002
An approximate integral model with an artificial neural network for heat exchangers
Authors: Ding Guo‐Liang , Zhang Chun‐Lu , Zhan Tao 
Published: April 2004

AbstractIn order to improve predicting precision and increase computation speed of simulation for heat exchangers, a novel method is presented in this paper, whereby an approximate integral model is used to simplify the original distributed parameter model and an artificial neural network is combined to reflect the nonlinear relations. This model is applied in actual calculations of fin‐and‐tube condensers and high precision is achieved. Where the calculated outlet temperature of refrigerant and that of air, the average errors are both less than 0.2 °C. For the heat exchange of the condenser, the average error is less than 1 0.2 °C. For the heat exchange of the condenser, the average error is less than 1%. The calculation speed of the approximate integral model is two orders of magnitude faster than that of the distributed‐parameter model. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(3): 153–160, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20006
Endwall heat transfer and film cooling measurements in a turbine cascade with injection upstream of leading edge
Authors: Liu Gaowen , Liu Songling , Zhu Huiren , Lapworth B.L. , Forest A.E. 
Published: April 2004

AbstractDetailed heat transfer measurements were conducted on the endwall surface of a large‐scale low‐speed turbine cascade with single and double row injection on the endwall upstream of leading edge. Local film cooling effectiveness and the heat transfer coefficient with coolant injection were determined at blowing ratios 1.0, 2.0, and 3.0. In conjunction with the previously measured flow field data, the behaviors of endwall film cooling and heat transfer were studied. The results show that endwall film cooling is influenced to a great extent by the secondary flow and the coverage of coolant on the endwall is mainly determined by the blowing ratio. An uncovered triangle‐shaped area with low effectiveness close to pressure side could be observed at a low blowing ratio injection. The averaged effectiveness increases significantly when injecting at medium and high blowing ratios, and uniform coverage of coolant on the endwall could be achieved. The averaged effectiveness could be doubled in the case of double row injection. It was also observed that coolant injection made the overall averaged heat transfer coefficient increase remarkably with blowing ratio. It was proven that film cooling could reduce endwall heat flux markedly. The results illustrate the need to take such facts into account in the design process as the three‐dimensional flow patterns in the vicinity of the endwall, the interactions between the secondary flow and coolant, and the augmentation of heat transfer rate in the case of endwall injection. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(3): 141–152, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20007
Structural changes of fibronectin adsorbed to model surfaces probed by fluorescence resonance energy transfer
Authors: Baugh Loren , Vogel Viola 
Published: April 2004

AbstractStructural changes of proteins during adsorption to biomaterials affect the presentation of molecular binding sites and, ultimately, biomaterial performance. We have applied fluorescence resonance energy transfer (FRET) spectroscopy to study structural changes of the cell adhesion protein, fibronectin (Fn), following adsorption to model hydrophilic and hydrophobic surfaces. Fn was labeled with donor and acceptor fluorophores using two labeling schemes and intramolecular energy transfer was calibrated against measured structural changes of Fn in denaturing solutions. FRET was then applied to measure Fn's structure on surfaces. Based on FRET, Fn underwent greater extension of its dimer arms on hydrophilic glass than on hydrophobic fluoroalklysilane‐derivatized glass (fluorosilane), and this extension was insensitive to molecular packing over a range of adsorption concentrations. Fn's conformation on glass better promoted cell attachment than on fluorosilane; the roles of both global structural changes (movements of modules) and local structural changes (disruption of secondary structure) on Fn's cell integrin binding activity are discussed. Based on previous FRET work, we compare Fn's conformations on these surfaces with its conformations in fibroblast culture. FRET is unique in allowing direct comparison of protein structure between biomaterial surfaces and cell culture. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 525–534, 2004
Binding of two nuclear factors to a novel silencer element in human dentin matrix protein 1 (DMP1) promoter regulates the cell type‐specific DMP1 gene expression
Authors: Chen Shuo , Inozentseva‐Clayton Natalyia , Dong Juan , Gu Ting Ting , MacDougall Mary 
Published: April 2004

AbstractDMP1 is an acidic phosphorylated protein with the spatial and temporal expression that is largely restricted to bone and tooth tissues. The biological function of DMP1 is associated with biomineralization of bone, cartilage and tooth development. To study the cell‐specific expression of DMP1, a 2,512 bp upstream segment of the human gene was isolated and characterized. A series of progressive deletions of the human DMP1 5′ flanking sequence were ligated to the luciferase reporter gene, and their promoter activities examined in transfected human osteoblast‐like (MG‐63) and dental pulp (HDP‐D) cells that express DMP1 and hepatic (HepG2) and uterine (HeLa) cells lacking DMP1 expression. A critical cis‐regulatory element located between nt −150 and −63 was found to act as a specific silencer responsible for the negative regulation of DMP1 in HepG2 and HeLa cells. The transcriptional activity of this element in MG‐63 and HDP‐D cells had a 5–7‐fold increase than that observed in HepG2 and HeLa cells. Electrophoretic mobility shift assays (EMSAs) showed that a 6‐bp DNA sequence in this element was bound by two nuclear factors that are expressed at high levels in HepG2 and HeLa versus MG‐63 and HDP‐D cells. Competitive assays by EMSAs suggest that the 6‐bp core DNA sequence, AG(T/C)C(A/G)C, is a novel DNA–protein binding site and conserved with high identity in reported DMP1 promoters for all species. Furthermore, point mutations of the core sequence caused a marked increase of DMP1 promoter activity in HepG2 and HeLa cells. We speculate that this silencing cis‐element may play a critical role in the regulation of DMP1 cell‐specific expression. © 2004 Wiley‐Liss, Inc.
Ryanodine receptor signaling is required for anti‐CD3‐induced T cell proliferation, interleukin‐2 synthesis, and interleukin‐2 receptor signaling
Authors: Conrad David M. , Hanniman Elyisha A. , Watson Carrie L. , Mader Jamie S. , Hoskin David W. 
Published: April 2004

AbstractRyanodine receptors (RyR) are involved in regulating intracellular Ca++ mobilization in T lymphocytes. However, the importance of RyR signaling during T cell activation has not yet been determined. In this study, we have used the RyR‐selective antagonists, ruthenium red and dantrolene, to determine the effect of RyR blockade on T cell receptor‐mediated activation events and cytokine‐dependent T cell proliferation. Both ruthenium red and dantrolene inhibited DNA synthesis and cell division, as well as the synthesis of interleukin (IL)‐2 by T lymphocytes responding to mitogenic anti‐CD3 antibody. Blockade of RyR at initiation of culture or as late as 24 h after T cell receptor stimulation inhibited T cell proliferation, suggesting a requirement for sustained RyR signaling during cell cycle progression. Although flow cytometry revealed that RyR blockade had little effect on activation‐induced expression of the α chain (CD25) of the high affinity IL‐2 receptor, the inhibitory effect of RyR antagonists could not be reversed by the addition of exogenous IL‐2 at initiation of culture. In addition, both ruthenium red and dantrolene had a strong inhibitory effect on IL‐2‐dependent proliferation of CTLL‐2 T cells. These data indicate that RyR are involved in regulating IL‐2 receptor signaling that drives T cell progression through the cell cycle. We conclude that RyR‐associated Ca++ signaling regulates T cell proliferation by promoting both IL‐2 synthesis and IL‐2‐dependent cell cycle progression. © 2004 Wiley‐Liss, Inc.
Repression of the human immunodeficiency virus type‐1 long terminal repeat by the c‐Myc oncoprotein
Authors: Stojanova A. , Caro C. , Jarjour R.J.V. , Oster S.K. , Penn L.Z. , Germinario R.J. 
Published: April 2004

AbstractThe effect of trans‐acting factors on cis‐acting DNA elements on the HIV‐1 promoter are the principal determinant regulating transcriptional activation and repression. Host factors that limit viral replication can contribute to the emergence and maintenance of proviral reservoirs. The current paradigm is that this sub‐population of latently infected cells confers a biological advantage to the virus by facilitating evasion of immunologic responses and therapeutic strategies resulting in life‐long and persistent infection. In this report, we show that ectopic expression of the nuclear phosphoprotein, c‐Myc can inhibit HIV‐1 gene expression and virus production in CD4+ T‐lymphocytes. The effect exerted does not appear to involve other known functions of c‐Myc such as proliferation, or apoptosis. The mechanism does implicate c‐Myc in a direct role. We have found evidence that c‐Myc can specifically recognize the HIV‐1 initiator element surrounding the start site of transcription and linker scanning mutagenesis experiments confirmed a loss of c‐Myc‐mediated repression in the absence of this region. Moreover, we show that c‐Myc can interact with the initiator binding proteins YY‐1 and LBP‐1 and can cooperate with these factors to synergistically repress HIV‐1 LTR transcription. Taken together, these results indicate that c‐Myc is an important regulator of HIV‐1 transcription that potentially contributes to the latent proviral state. © 2004 Wiley‐Liss, Inc.
Heparin modulates the growth and adherence and augments the growth‐inhibitory action of TNF‐α on cultured human keratinocytes
Authors: Harvima Ilkka T. , Lappalainen Katriina , Hirvonen Maija‐Riitta , Mättö Mikko , Kivinen Petri K. , Hyttinen Mika , Pelkonen Jukka , Naukkarinen Anita 
Published: April 2004

AbstractPrevious works suggest the involvement of mast cells in the epithelialization of chronic wounds. Since heparin is a major mediator stored in the secretory granules of mast cells, the purpose of this work was to elucidate the function of heparin in epithelialization using in vitro culture models. For this, low‐ and high‐calcium media in monolayer and epithelium cultures of keratinocytes were used. Also, an assay based on keratinocyte adherence onto plastic surface was used as well. Heparin (0.02–200 μg/ml) inhibited keratinocyte growth in a non‐cytotoxic and dose‐dependent manner in low‐ and high‐calcium media, Keratinocyte‐SFM® and DMEM, in the absence of growth factors and serum. Also, heparin inhibited the growth of keratinocyte epithelium in the presence of 10% fetal calf serum and DMEM. Instead, in the presence of Keratinocyte‐SFM and growth factors, heparin at 2 μg/ml inhibited the growth by 18% but at higher heparin concentrations the inhibition was reversed to baseline. TNF‐α is another preformed mediator in mast cell granules and it inhibited keratinocyte growth in monolayer and epithelium cultures. Interestingly, heparin at 2–20 μg/ml augmented or even potentiated this growth‐inhibitory effect of TNF‐α. The association of TNF‐α with heparin was shown by demonstrating that TNF‐α bound tightly to heparin‐Sepharose chromatographic material. However, heparin could not augment TNF‐α‐induced cell cycle arrest at G0/G1 phase or intercellular adhesion molecule‐1 expression in keratinocytes. In the cell adherence assay, heparin at 2 μg/ml inhibited significantly by 12–13% or 33% the adherence of keratinocytes onto the plastic surface coated with fibronectin or collagen, respectively, but this inhibition was reversed back to baseline at 20 or 200 μg/ml heparin. Also, heparin affected the cell membrane rather than the protein coat on the plastic surface. In conclusion, heparin not only inhibits or modulates keratinocyte growth and adherence but it also binds and potentiates the growth‐inhibitory function of TNF‐α. © 2004 Wiley‐Liss, Inc.
Effect of homocysteinylation of low density lipoproteins on lipid peroxidation of human endothelial cells
Authors: Ferretti Gianna , Bacchetti Tiziana , Moroni Cinzia , Vignini Arianna , Nanetti Laura , Curatola Giovanna 
Published: April 2004

AbstractHomocysteine‐thiolactone (HcyT) is a toxic product whose synthesis is directly proportional to plasma homocysteine (Hcy) levels. Previous studies demonstrated that the interaction between HcyT and low density lipoproteins (LDL) induces the formation of homocystamide‐LDL adducts (Hcy‐LDL). Structural and functional alterations of Hcy‐LDL have been described and it has been suggested that homocysteinylation could increase atherogenicity of LDL. Oxidative damage of endothelial cells (EC) is considered to be a critical aspect of the atherosclerotic process. To further investigate the molecular mechanisms involved in the atherogenicity of homocysteinylated LDL, we studied the effect of interaction between Hcy‐LDL and EC on cell oxidative damage, using human aortic endothelial cells (HAEC) as experimental model. Homocysteinylation of LDL was carried out by incubation of LDL, isolated from plasma of healthy normolipemic subjects, with HcyT (10–100 μM). In our experimental conditions, homocysteinylation treatment was not accompanied by oxidative damage of LDL. No modifications of apoprotein structure and physico‐chemical properties were observed in Hcy‐LDL with respect to control LDL (c‐LDL), as evaluated using the intrinsic fluorescence of tryptophan and the probe Laurdan incorporated in lipoproteins. Our results demonstrated that Hcy‐LDL incubated at 37°C for 3 h with HAEC, induced an oxidative damage on human EC with a significant increase of lipid hydroperoxides in cells incubated with Hcy‐LDL with respect to cell incubated with c‐LDL. The compositional changes were associated with a significant decrease viability in cells treated with Hcy‐LDL. The relationship between the levels of –SH groups of LDL and the oxidative damage of HAEC has been demonstrated. These results suggest that Hcy‐LDL exert a cytotoxic effect that is likely related to an increase in lipid peroxidation and oxidative damage of EC. © 2004 Wiley‐Liss, Inc.