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排序方式: 共有1597条查询结果,搜索用时 718 毫秒
121.
Matthias Augustin Alfonso Caiazzo André Fiebach Jürgen Fuhrmann Volker John Alexander Linke Rudolf Umla 《Computer Methods in Applied Mechanics and Engineering》2011,200(47-48):3395-3409
The performance of several numerical schemes for discretizing convection-dominated convection–diffusion equations will be investigated with respect to accuracy and efficiency. Accuracy is considered in measures which are of interest in applications. The study includes an exponentially fitted finite volume scheme, the Streamline-Upwind Petrov–Galerkin (SUPG) finite element method, a spurious oscillations at layers diminishing (SOLD) finite element method, a finite element method with continuous interior penalty (CIP) stabilization, a discontinuous Galerkin (DG) finite element method, and a total variation diminishing finite element method (FEMTVD). A detailed assessment of the schemes based on the Hemker example will be presented. 相似文献
122.
Volker John Petr Knobloch Simona B. Savescu 《Computer Methods in Applied Mechanics and Engineering》2011,200(41-44):2916-2929
Stabilized finite element methods for convection-dominated problems require the choice of appropriate stabilization parameters. From numerical analysis, often only their asymptotic values are known. This paper presents a general framework for optimizing stabilization parameters with respect to the minimization of a target functional. Exemplarily, this framework is applied to the SUPG finite element method and the minimization of a residual-based error estimator, an error indicator, and a functional including the crosswind derivative of the computed solution. Benefits of the basic approach are demonstrated by means of numerical results. 相似文献
123.
Jewe Schröder Stefan KrausBruna Bertolla Rocha Volker GaukelHeike P. Schuchmann 《Journal of food engineering》2011,105(4):656-662
Effervescent atomization is a promising method for economical atomization of high viscous liquids like gelatinized corn starch suspensions. The gelatinization of starch has strong influence on the viscosity of starch suspensions. It was characterized adapting a method for determination of the gelatinization degree. Rheological properties of gelatinized corn starch suspensions with concentrations ranging from 5 to 7 wt.-% were investigated. Effervescent atomization proved to be largely invariant to variations of liquid viscosity in this range. Relative gas injection pressure proved to be of highest influence on the resulting drop size distribution when varying only atomizer geometry. Applying Abel inversion to drop size measurement results depicted the opposite trend of drop sizes depending on radial position in the spray than observed by other researchers working with aqueous glass bead suspensions. Compared to conventional external mixing pneumatic atomization a reduction of atomization gas quantity of up to four times could be achieved. 相似文献
124.
Himani Gaur Jain Hatice Karacuban David Krix Hans-Werner Becker Hermann Nienhaus Volker Buck 《Carbon》2011,49(15):4987-4995
Well aligned carbon nanowalls, a few nanometers thick, were fabricated by continuous flow of aluminum acetylacetonate (Al(acac)3) without a catalyst, and independent of substrate material. The nanowalls were grown on Si, and steel substrates using inductively coupled plasma-enhanced chemical vapor deposition. Deposition parameters like flow of argon gas and substrate temperature were correlated with the growth of carbon nanowalls. For a high flow of argon carrier gas, an increased amount of aluminum in the film and a reduced lateral size of the carbon walls were found. The aluminum is present inside the carbon nanowall matrix in the form of well crystallized nanosized Al4C3 precipitates. 相似文献
125.
Dipl.‐Ing. Volker Lenz Dipl.‐Ing. Marian Schenker Dipl.‐Ing. Christian Thiel Prof. Dr. Wolf‐Dietrich Einicke M.Sc. René Bindig Dr. rer. nat. Ulf Roland 《化学,工程师,技术》2011,83(3):371-376
In addition to the reduction of particulate matter, a catalytic supported emission reduction in small scale biomass combustion systems can also enable a conversion of toxic organic components into carbon dioxide and water. For catalyst investigations under practical conditions a special test facility was designed. The results show that products of incomplete combustion like carbon monoxide from stoves can be reduced by catalytic processes. Further developments and studies are necessary to achieve the targeted emission limits. 相似文献
126.
Caroline Danowski Volker Gravemeier Lena Yoshihara Wolfgang A. Wall 《International journal for numerical methods in engineering》2013,95(13):1053-1078
In the present work, a monolithic solution approach for thermo‐structure interaction problems motivated by the challenging application of the behaviour of rocket nozzles is proposed. Structural and thermal fields are independently discretised via finite elements. The resulting system of equations is solved via a monolithic thermo‐structure interaction scheme, which is constructed by a block Gauss–Seidel preconditioner in combination with algebraic multigrid methods. The proposed method is tested for four numerical examples, the second Danilovskaya problem, a simplified rocket nozzle configuration, an internally loaded hollow sphere, and a fully three‐dimensional nozzle configuration of a subscale thrust chamber. Good agreement of the numerical results with results from the literature is observed. Furthermore, it is shown that the monolithic solution algorithm can handle the complete range of the parameter spectrum, whereas partitioned algorithms are limited to a certain parameter range only. Moreover, the monolithic algorithm exhibits improved efficiency and robustness compared to partitioned algorithms. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
127.
128.
Christian J. Cyron Keijo Nissen Volker Gravemeier Wolfgang A. Wall 《Computational Mechanics》2010,46(2):287-300
Recently, stable meshfree methods for computational fluid mechanics have attracted rising interest. So far such methods mostly
resort to similar strategies as already used for stabilized finite element formulations. In this study, we introduce an information
theoretical interpretation of Petrov–Galerkin methods and Green’s functions. As a consequence of such an interpretation, we
establish a new class of methods, the so-called information flux methods. These schemes may not be considered as stabilized
methods, but rather as methods which are stable by their very nature. Using the example of convection–diffusion problems,
we demonstrate these methods’ excellent stability and accuracy, both in one and higher dimensions. 相似文献
129.
Ohne Zusammenfassung
Eingang des Beitrages: 23.04.97 相似文献
130.
Microalloyed medium-carbon steels with ferrite-pearlite microstructure were developed in the FRG in early 1972, with the primary aim of saving the cost of heat treatment. A steel with roughly 0.47% C, 0.75% Mn, 0.060% S and 0.1 % V was first used for crankshafts in cars manufactured by one of the largest European automobile companies. The effect of microalloying elements such as vanadium and niobium (niobium instead of columbium is used in this paper) in these steels and their dependence on the cooling rate from drop-forging temperatures is reviewed. Although niobium is more effective than vanadium, it leads to problems while manufacturing these steels with ~0.47% C, due to the high solution temperature of the niobium precipitates, so that preference has been given to vanadium. Further development work carried out to improve the ductility of these steels is reported. Steel compositions, which could make these steels applicable for various automobile and other engineering components, are presented. 相似文献