Academic literature on the topic 'Inclined domain'
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Journal articles on the topic "Inclined domain"
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Sementsov, D. I. "Diffraction of Light from Stripe Domain Structure with Inclined Domain Boundaries." Crystallography Reports 45, no. 6 (November 2000): 995. http://dx.doi.org/10.1134/1.1327666.
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Darinskii, B. M., and V. V. Gorbynov. "Instability of inclined 180° domain boundary in ferroelectrics." Ferroelectrics 98, no. 1 (October 1989): 235–40. http://dx.doi.org/10.1080/00150198908217584.
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Nakai, Tomoo. "Magnetic Domain Transition of Adjacent Narrow Thin Film Strips with Inclined Uniaxial Magnetic Anisotropy." Micromachines 11, no. 3 (March 8, 2020): 279. http://dx.doi.org/10.3390/mi11030279.
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This study deals a phenomenon of magnetic domain transition for the stepped magneto-impedance element. Our previous research shows that an element with 70° inclined easy axis has a typical characteristic of the domain transition, and the transition can be controlled by the normal magnetic field. In this paper, we apply this phenomenon and controlling method to the line arrangement adjacent to many body elements, in which mutual magnetic interaction exists. The result shows that the hidden inclined Landau–Lifshitz domain appears by applying a distributed normal field the same as an individual element.
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Su, Yan. "Numerical Researches of Rectangular Barge in Variable Bathymetry Based on Boussinesq-Step Method." Advances in Civil Engineering 2022 (August 18, 2022): 1–9. http://dx.doi.org/10.1155/2022/2209394.
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Wave responses of the rectangular barge in variable bathymetry are investigated by combining the Boussinesq-type equations and the step method. The highly accurate Boussinesq-type equations in terms of velocity potential are adopted for simulating the evolution of waves along the inclined beach. Hydrodynamic coefficients of a rectangular barge floating on the inclined bottom are calculated by the step method in the frequency domain. Based on the impulse response function method, the motions of the barge can be predicted in the time domain. The Haskind relation is used to reform the wave exciting forces, and the mean offset in the sway motion is also given based on the mean drift force. The wave responses of the barge at different locations along the inclined beach are measured in the experiments. Compared with experimental results, the solutions of the Boussinesq-step method present an overall good agreement.
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Boonloi, Amnart, and Withada Jedsadaratanachai. "Thermohydraulic Performance Improvement in Heat Exchanger Square Duct Inserted with 45° Inclined Square Ring." Modelling and Simulation in Engineering 2020 (January 13, 2020): 1–22. http://dx.doi.org/10.1155/2020/3862624.
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Thermal performance development, heat transfer structure, and flow behavior in the heat exchanger square duct equipped with a 45° inclined square ring are investigated numerically. The effects of flow blockage ratios and spacing ratios for the inclined square ring on fluid flow and heat transfer are considered. The Reynolds number (Re = 100–2000, laminar regime) based on the hydraulic diameter of the square duct is selected for the present work. The numerical domain of the square duct inserted with the 45° inclined square ring is solved with the finite volume method. The SIMPLE algorithm is picked for the numerical investigation. The heat transfer characteristics and flow topologies in the square duct inserted with the inclined square ring are plotted in the numerical report. The heat transfer rate, pressure loss, and efficiency for the square duct placed with the inclined square ring are presented in forms of Nusselt number, friction factor, and thermal enhancement factor, respectively. As the numerical results, it is detected that the heat transfer rate of the heat exchanger square duct inserted with the inclined square ring is around 1.00–10.05 times over the smooth duct with no inclined square ring. Additionally, the maximum thermal enhancement factor for the heat exchanger square duct inserted with the inclined square ring is around 2.84.
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Valera Sifontes, Rimary, Hédison Kiuity Sato, and Zoukaneri Ibrahim Moumoni. "Relief geometric effects on frequency-domain electromagnetic data." GEOPHYSICS 81, no. 5 (September 2016): E287—E296. http://dx.doi.org/10.1190/geo2015-0344.1.
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A perpendicular transmitter-receiver coils arrangement used in the frequency-domain electromagnetic survey can have deviations in relation to its standard geometric definition due to the relief geometry of the surveyed area when combined with large transmitter-receiver distance and large transmitter loop size. This happens because the local relief characteristics along the transmitter loop wire laid on the ground can deviate the equivalent magnetic moment axis from the vertical, and the global characteristics locate the transmitter and receiver positions at different elevations. A study about that is carried on here substituting the rugged relief by an inclined plane. We have developed a new formulation for the [Formula: see text]-layered model that allowed us to investigate the relief geometry effects on FDEM data but restricting the analysis to the two-layer earth model, considering three cases of transmitter-receiver situations controlled by the relief conditions. The curves representing the Argand diagram and the apparent polarization parameter as a function of the apparent induction number were obtained for each relief model. Such procedures resulted to be very useful to demonstrate their behavior departing from those curves obtained for an inclined and a horizontal ground. These results show that small deviations in the verticality of the transmitter loop axis or in the horizontality of the surficial plane causes significant deviations, even for angles as small as 1°.
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Lazoglu, Ismail, and Steven Y. Liang. "Modeling of Ball-End Milling Forces With Cutter Axis Inclination." Journal of Manufacturing Science and Engineering 122, no. 1 (February 1, 1999): 3–11. http://dx.doi.org/10.1115/1.538885.
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In the machining of sculpture surfaces with ball-end mill, the cutter axis or workpiece is often inclined to generate an admissible orientation. This paper primarily presents an enhanced cutting force model for ball-end milling with cutter axis inclination. It involves the kinematic reasoning of cutting edge geometry, local helix angle and average chip thickness followed by the analysis of effects of axis inclination in the contact zone between cutter and workpiece. Thereupon, development of the analytical force model for inclined-axis machining is achieved using cutter angle domain convolution method. Experimental evaluation of the model is discussed, and experimental results and model predictions under various cutting conditions are compared in the frequency as well as in the angular domain. [S1087-1357(00)70601-0]
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Socolowsky, Jürgen. "ON A TWO-FLUID INCLINED FILM FLOW WITH EVAPORATION." Mathematical Modelling and Analysis 18, no. 1 (February 1, 2013): 22–31. http://dx.doi.org/10.3846/13926292.2013.756434.
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This paper is concerned with a plane steady-state inclined film flow including evaporation effects. The motion is governed by a free boundary value problem for a coupled system of Navier–Stokes and Stefan equations. The flow domain is unbounded in two directions and it contains a geometrical perturbation on the inclined bottom. Existence and uniqueness of a suitable solution in weighted Sobolev spaces can be proved for small data (perturbation, inclination of the bottom) characterizing the problem.
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Krawczyszyn, J. "Movement of the cambial domain pattern and mechanism of formation of interlocked grain in Platanus." Acta Societatis Botanicorum Poloniae 41, no. 4 (2015): 443–61. http://dx.doi.org/10.5586/asbp.1972.036.
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The orientation of splitting and uniting of rays, which served as an indicator of the orientation of morphogenic events occurring in cambium, was determined on series of veneers covering large tangential faces of <i>Platanus</i> trunks. It has been shown that cambium consists of orientational domains of Z- and S-type. They are perpendicular to, or slightly inclined with respect to, the trunk axis. Axial dimensions of domains are 8-28 cm. They move upward along the trunk, at a rate 6,5—12 mm, per radial mm of xylem porduced. Migration domain patterns are responsible for the formation of the interlocked grain.
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Zhu, Chang Jiang, and Wen Kui Zheng. "Research of Potential Inclined Intrusion Data Mining Method in Large Network." Applied Mechanics and Materials 543-547 (March 2014): 2024–27. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.2024.
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Network intrusion is shown in more and more concealment, and some intrusion data is potential with inclination property. This paper is aimed to mine the potential inclined intrusion data effectively, and ensure the security of large network. On the basis of the traditional fractional Fourier transform data mining method. An improved potential inclined intrusion accurate data mining algorithm is proposed. New algorithm can separate the time and frequency coupling effectively. The discrete fractional Fourier transform is implemented for the network intrusion data firstly. The data is gathered in the fractional Fourier domain, the inclined intrusion data accumulation is increased. The network signal interference is suppressed effectively. Simulation results show that the proposed data mining algorithm can extract the potential inclined intrusion data in strong concealment. The mining performance is much better than the traditional algorithm, and it can be applied in the network security defense area perfectly.
Dissertations / Theses on the topic "Inclined domain"
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Fahs, Amin. "Modeling of naturel convection in porous media : development of semi-analytical and spectral numerical solutions of heat transfer problem in special domains." Thesis, Strasbourg, 2021. https://publication-theses.unistra.fr/restreint/theses_doctorat/2021/Fahs_Amin_2021_ED269.pdf.
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Le problème de la cavité poreuse carrée est largement utilisé comme cas de référence courant pour les problèmes de Convection Naturelle (CN) en milieux poreux. Il peut être utilisé pour plusieurs applications numériques, théoriques et pratiques. Par ailleurs, toutes les solutions de haute précision existantes dans la littérature scientifique sont développées dans des conditions de régime permanent. Cependant, il est bien connu que les processus de CN dans les milieux poreux se produisent naturellement dans un régime dépendant du temps, car les conditions aux limites peuvent être variables dans le temps. Pour surmonter cette difficulté, la solution en régime permanent est souvent simulée comme une solution transitoire qui évolue jusqu'à atteindre l'état d'équilibre. Ces régimes dépendant du temps sont très efficaces pour détecter les effets des variations de paramètres sur le processus physique de CN, en particulier pour les sujets d'intérêt de cette thèse: la variation du niveau d'inclinaison du domaine et la prise en compte des variations de température de la paroi chaude dans le temps. À cet effet, trois objectifs sont identifiés dans cette thèse: 1. Développer une solution de convection naturelle en fonction du temps dans des milieux poreux en utilisant le Modèle Darcy en deux modes: transitoire et instable. 2. Étudier le comportement en fonction du temps de la convection naturelle dans des milieux poreux ayant le niveau d'inclinaison du domaine comme paramètre variable dans deux modes: transitoire et instable. 3. Développer une solution de convection naturelle en fonction du temps dans des milieux poreux en utilisant le Modèle Darcy-Lapwood-Brinkman en deux modes: transitoire et instable. Pour ce faire, du fait de la grande précision dans les domaines simplement connectés, une méthode spectrale de résidus pondérés de type Galerkin est choisie pour développer une solution au problème de CN dans une cavité carrée poreuse. L’application de la procédure de Fourier-Galerkin (FG), deux configurations traitant des régimes instables sont considérées où chaque solution est dérivée pour une large gamme des nombres de Rayleigh (Ra) avec d'autres conditions spéciales. Ce travail de thèse est subdivisé en cinq chapitres. Dans le premier chapitre, nous avons présenté un aperçu physique du processus de convection naturelle en milieux poreux. Dans le deuxième chapitre, le développement mathématique des équations, la méthode de résolution et la procédure de résolution sont décrits en détails. Dans le chapitre trois, la première étude de cas de cette thèse, la solution dépendante du temps de la convection naturelle dans une cavité carrée remplie de milieux poreux saturé utilisant le modèle de Darcy est développé. Dans le chapitre quatre, le problème de variation temporelle de Darcy-Lapwood- Brinkman de CN dans une enceinte poreuse saturée carrée est étudié. Dans le chapitre cinq, les solutions dépendant du temps sont développées pour le problème de convection naturelle utilisant la loi de Darcy dans une cavité poreuse inclinée et considéré comme une étude complète sur les effets de l'inclinaison du domaine sur le processus physique du problème de convection libre. Pour tous les cas, les régimes transitoires et instables sont considérésThe problem of the porous square cavity is extensively used as a common benchmark case for Natural convection (NC) problem in porous media. It can be used for several numerical, theoretical, and practical purposes. All the existing high accurate solutions are developed under steady-state conditions. However, it is well known that the processes of NC in porous media occurs naturally in a time-dependent procedure, as boundary conditions can be variable in time. Also, the convergence of the steady-state solution is known to be difficult. To overcome this difficulty, the steady-state solution is often simulated as a transient solution that evolves until reaching the steady-state condition. These time-dependent modes are very efficient to detect the effects of the parameter variations on the physical process of NC, especially for the subject of interest in this thesis: the domain inclination level and hot wall temperature variation in time. For this purpose, three goals are identified in this Thesis: 1. Developing a time-dependent solution of natural convection in porous media using the Darcy model in two modes: Transient and unsteady. 2. Investigating the time-dependent behavior of natural convection in porous media having the domain inclination level as a variable parameter in two modes: Transient and unsteady. 3. Developing a time-dependent solution of natural convection in porous media using the Darcy-Lapwood-Brinkman model in two modes: Transient and unsteady. To do so, according to the high accuracy in the simply connected domains, one of the Galerkin spectral weighted residual method is chosen to develop a space-time dependent solution for NC problem in a square porous cavity. Applying the Fourier-Galerkin (FG) procedure, two configurations dealing with transient and unsteady regimes are considered where each solution is derived for a wide range of Rayleigh numbers with other special conditions. This work of thesis is explained in details as five chapters.The NC physical process with the time-dependent variations is described in the transient mode to reach the steady-state solution and for the unsteady mode during a one period using periodic sinusoidal boundary conditions on the cavity hot wall. Finally, the work of this thesis is described in details in five chapters; while the sixth and last chapter is devoted to the summary and conclusion.The results in this thesis work provide a set of high-accurate data that are published in three papers to be used for testing numerical codes of heat transfer in time-dependent configurations
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Ruyer-Quil, Christian. "Dynamique d'un film mince s'ecoulant le long d'un plan incline." Palaiseau, Ecole polytechnique, 1999. http://www.theses.fr/1999EPXX0046.
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L'ecoulement d'un film mince visqueux le long d'un plan incline est un prototype d'ecoulement ouvert avec surface libre, caracterise par la presence d'ondes solitaires et d'une suite bien definie d'instabilites secondaires conduisant au chaos spatio-temporel. L'objectif de cette these est de developper des modeles mathematiques permettant une description a la fois qualitative et quantitative des instabilites secondaires tridimensionnelles du film. La demarche suivie combine une methode aux residus ponderes dans la direction normale au film a un developpement en gradients, ceci afin d'eliminer les degres de liberte esclaves de l'epaisseur h du film. Un premier modele, obtenu en utilisant les profils de vitesse asymptotiques au voisinage du seuil et une methode de moyennage et de collocations aux frontieres, est presente en annexe (ch. 10). Une demarche plus systematique est exposee ici et conduit au premier ordre a un systeme de deux equations couplees decrivant l'evolution de l'epaisseur h et du debit local q. Au second ordre le modele ainsi ecrit implique quatre equations. Cependant un modele au second ordre simplifie a deux champs (4. 65-4. 66) est obtenu en appliquant une methode de galerkin. A l'aide de la theorie des systemes dynamiques, la recherche des ondes stationnaires bidimensionnelles dans leur referentiel en mouvement met en evidence le role joue par la dispersion d'origine visqueuse quant a la possibilite de chaos homocline, a la forme des ondes solitaires et a la selection des familles d'ondes stationnaires. L'analyse de floquet des solutions de (4. 65-4. 66) reproduit les resultats theoriques anterieurs sans toutefois expliquer les observations experimentales. Enfin, les simulations numeriques du developpement spatial des solutions de (4. 65-4. 66) avec forcage periodique ou aleatoire se comparent tres favorablement a l'experience et a la simulation numerique directe.
Book chapters on the topic "Inclined domain"
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Dembour, Marie-Bénédicte. "Where are the Limits of Human Rights? Four Schools, Four Complementary Visions." In The Limits of Human Rights, 345–56. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198824756.003.0024.
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This comment makes sense of Delmas-Marty’s contribution by elaborating further the author’s four-school human rights model. It is surmised that as a predominantly natural scholar, Delmas-Marty is inclined to approach the limits of human rights as unfortunate ‘mishaps’—and to hold a universal view of the history of human rights. By contrast, Dembour’s arguable strong affiliation to the discourse school leads her to highlight human rights’ inherent defects—and historical failures. A deliberative scholar would tend to envisage the proper domain of human rights as restricted to political governance—and to produce human rights’ histories with a strong institutional focus. Finally, a protest scholar would expect human rights to be hijacked by the elite and to fail to produce the emancipatory results they promise—thus producing a history where the limited results which are achieved need to be constantly renewed.
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Demoulin, Alain. "Tectonic Evolution, Geology, and Geomorphology." In The Physical Geography of Western Europe. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780199277759.003.0010.
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The present-day major relief features of western Europe are to a great extent determined by the underlying geological structures, either passively or actively. To get a comprehensive picture of their morphological evolution and interrelations, this chapter provides an overview of the spatial and temporal characteristics of the larg-escale tectonic framework of the continent. After having described the west European landscape at the end of the Palaeozoic, to which time the oldest preserved landforms date back, an outline of the Mesozoic and Cenozoic history of the major tectonic domains follows. Finally, some denudation estimates highlighting the relationship between tectonics, erosion, and the resulting relief, will be discussed. The three main influences on the present-day topographic patterns are those of the Alpine orogeny, the Cenozoic West European rifting, and the imprint of Variscan structures. They combine within a regional stress field determined by the Africa–Eurasia collision and the Alpine push as well as the mid-Atlantic ridge push. Since the end of the Miocene, this stress field is characterized by a fan-shaped distribution of SHmax along the northern border of the Alpine arc. This gives way to a more consistent NW–SE to NNW–SSE direction of compression further from the chain (Bergerat 1987; Müller et al. 1992). Topographically, western Europe may be roughly divided into a series of belts parallel to the Alpine chain. The Alpine chain culminates in a number of peaks exceeding 4,000 m in elevation (4,810 m at Mont Blanc) but the average altitude is in the order of 2,000 m. To the north, the mountainous Alps are bordered by the Molasse foredeep basin whose surface makes an inclined plane descending northwards from c.1,000 m to c.300 m near the Donau River in the Regensburg-Passau area. To the north-west, the Molasse basin narrows between the Alps and the Jura Mountains and is occupied by several extended lakes inherited from Quaternary glacial activity. Next to the Molasse basin in the north and west is a wide belt of recently more or less uplifted areas between 200 and 1,000 m in elevation (and locally in excess of 1,000 m in the French Massif Central and the Bohemian massif).
Conference papers on the topic "Inclined domain"
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Luo, Albert C. J., and Brandon M. Rapp. "Switching Dynamics of a Periodically Forced Discontinuous System With an Inclined Boundary." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34863.
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This paper presents the switching dynamics of flow from one domain into another one in the periodically driven, discontinuous dynamical system. The simple inclined straight line boundary in phase space is considered as a control law for the dynamical system to switch. The normal vector-field product for flow switching on the separation boundary is introduced, and the passability condition of flow to the discontinuous boundary is presented. The sliding and grazing conditions to the separation boundary are presented as well. Using mapping structures, periodic motions of such a discontinuous system are predicted, and the local stability and bifurcation analysis are carried out. Numerical illustrations of periodic motions with grazing to the boundary and/or sliding on the boundary are given, and the normal vector fields are illustrated to show the analytical criteria.
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Kitayama, Satoshi, and Hiroshi Yamakawa. "A Study on Shape Optimization Using Affine Transformation." In ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/dac-21080.
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Abstract This paper presents a new method to determine an optimal shape using affine transformation which is used in the field of Computer Aided Design (CAD), linear programming, and etc. We use affine transformation as coordinate transformation. Affine transformation is a linear transformation, so that shapes transformed must be linearly. Shape optimization of a inclined beam for example, we can deal with in the following manner. We define a simple cantilever beam first in initial design domain, and calculate an optimal shape. Then we use affine transformation remaining with optimal shape calculated in simple design domain and get to an optimal shape of the inclined beam. To compare with an optimal shape obtained by our proposed method, we calculate an optimal shape directly by conventional method in the same design domain after coordinate transformation. We show that affine transformation plays a role as scaling to structural optimization by finite element method and that necessary and sufficient conditions between design variables and shape transformation matrix may exist to get an exact optimal shape. We treat some numerical examples by our proposed method. In numerical examples, we consider shape optimization of inclined cantilever beam for simplicity. We show that some stepwise linear optimal shapes could be expressed from an optimal shape of a simple cantilever beam by using affine transformation. Optimal shape calculated by our method can obtain easily and speedy. Through some numerical examples, we could examine effectiveness of our proposed method.
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Zhao, Yu, Hongyang Yu, Jingjie Sha, and Yunfei Chen. "A Convenient and Reliable Method of Manufacturing Inclined Bulk Graphite for Measuring Thermal Conductivity With TDTR." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10572.
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Abstract In this work, in order to study the thermal transport along arbitrary direction in bulk graphite, we develop a simple and convenient method to manufacture inclined bulk graphite applying Focused Ion beam (FIB). Then, we measure the thermal conductivity of inclined bulk graphite with the time-domain thermoreflectance (TDTR) technique and the measured results show that our processing method is reliable. Based on the TDTR measurement of inclined bulk graphite with a tilt angle of 90°, the in-plane thermal conductivity is on the order of 2030 Wm−1 K−1 and the cross-plane thermal conductivity is on the order of 5.5 Wm−1 K−1 at room temperature, which is close to the previously reported results. Our processing and measurement methods provide a new perspective on the study of the intrinsic mechanism of anisotropic thermal transport in anisotropic layered materials.
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Findlay, Matthew J., Pingfan He, Martha Salcudean, and Ian S. Gartshore. "A Row of Streamwise-Inclined Jets in Crossflow: Measurements and Calculations." In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-167.
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The velocity profiles and turbulence characteristics are measured for a row of square jets inclined at 30° to the streamwise direction. The jet spacing-to-width ratio is 3.0 and no temperature (density) difference between the jets and the crossflow is introduced. Measurements are made using a three-component LDV system operating in coincidence mode which provides three components of velocity and all six turbulent Reynolds stresses at each location. Jet-to-crossflow velocity ratios (blowing ratios) of 1.5. 1.0, and 0.5 are used and the jet Reynolds number is fixed at about 5000 for all velocity ratios. The results are compared with previous data from normal jets at the same blowing ratios so that the influence of inclination on vortex formation can be shown. Calculations are carried out for all cases using a non-orthogonal finite volume computer code with the k-ε turbulence model. It is shown that the flow field at the jet exit is strongly influenced by the crossflow as well as by the inlet conditions at the entrance to the jet orifice. Therefore it is very useful to extend the computational domain into the plenum. Computational results compared with experimental results for a velocity ratio of 0.5 agree reasonably well. Some under-prediction of the streamwise flow velocity is observed. The computed turbulence kinetic energy values also drop below the experimental values downstream and near the wall. Agreement is not as good for the higher velocity ratios, particularly for the turbulence kinetic energy. Strong non-isotropy of the turbulence field can be observed from the experimental data.
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Wang, Tongsheng, Zhu Huang, Zhongguo Sun, and Guang Xi. "Numerical Simulation of Mixed Flow Past an Inclined Square Cylinder Using a Local Radial Basis Function Method." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-5196.
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Abstract Unsteady mixed convective heat transfer flow past an inclined square cylinder is numerically investigated using a local multi-quadric radial basis function (MQRBF) interpolation. The blockage parameter (ratio of square cylinder length d to height of the computational domain H) varies from 0.025 to 0.2. Air is considered as the working fluid and Prandtl number is fixed at 0.71. Richardson number generally affects the heat transfer efficiency ranging from 0 to 20. Inclined angle of square cylinder ranges from 0° to 45°. The inlet flow is assumed to be laminar and uniform. At the outlet of the computational domain, a convective boundary condition is compared with a traditional Neumann condition. A study of the shape parameter of MQRBF which is sensitive to the distribution of inhomogeneous supporting nodes is provided. The representative streamlines, vortex structures and isotherm patterns are presented and discussed. In addition, the overall lift and drag coefficients, average Nusselt number and Strouhal number for unsteady flow are analyzed for various Reynolds number and Richardson number.
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Zamiri, Ali, Byung Ju Lee, and Jin Taek Chung. "Numerical Investigation of the Inclined Leading Edge Diffuser Vane Effects on the Flow Unsteadiness and Noise Characteristics in a Transonic Centrifugal Compressor." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-65117.
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The three-dimensional, compressible, unsteady Navier-Stokes equations are solved to investigate the influence of the inclined leading edge diffuser vanes on the flow field and radiated noise from a transonic centrifugal compressor with high compression ratio. The computational domain is consisted of an inlet duct and a rotating impeller with splitter blades followed by a two-dimensional wedge vaned diffuser. The numerical method was validated by comparing the steady computational results with those of experiments in terms of pressure ratio and compressor efficiency at different operating points for the original diffuser. The transient simulations were verified by comparison of the velocity distribution with PIV data in normal flow condition before the onset of surge. In the case of steady simulations, seven types of diffuser vane with various inclination angles of leading edge were numerically modeled to investigate the effects of inclined leading edge on the diffuser pressure recovery and total pressure loss characteristics. The vaned diffuser with inclined leading edge reduces the interaction between the impeller discharge flow and diffuser leading edge which leads to improve the pressure recovery characteristics within the diffuser passage. Detailed flow analysis inside the diffuser passage showed the pressure ratio and compressor efficiency have been improved by the inclined leading edges. The maximum diffuser pressure recovery coefficient, 0.7185, and compressor efficiency, 84.80%, were observed in the case of 30 degree inclination angle from hub-to-shroud. In the case of transient simulations, five different inclined leading edge diffuser vanes were numerically conducted. The present study focuses on the unsteady pressure fluctuations and noise prediction within the impeller and diffuser passages at the compressor design point. The influences of inclination angle of diffuser vane leading edges on the pressure waves with different convective velocities, generated by the impeller-diffuser interaction and pseudo-periodic unsteady separation bubbles, were captured in the time/space domain along the diffuser blade surfaces. Since it is important to understand that the far-field acoustics are dominated by the internal pressure fluctuations inside the passages, the near-field pressure fluctuation spectra captured at the impeller-diffuser interface are evaluated to analyze the tonal BPF noise as the main noise source in the centrifugal compressors. It is shown that the inclined leading edges are very useful not only for improvement of the pressure recovery characteristics within the diffuser but also for the reduction of the interaction tonal BPF noise (around 7.6 dB SPL reduction). Furthermore, it was found that by using the inclined leading edge, the vortical structures and separations within the diffuser passages were reduced which may cause the attenuation of the broadband noise components and the overall sound pressure level.
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He, Pingfan, Martha Salcudean, and Ian S. Gartshore. "Computations of Film Cooling for the Leading Edge Region of a Turbine Blade Model." In ASME 1995 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/95-gt-020.
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Computations of film cooling are presented based on the geometry of a UBC experimental turbine blade model. This model has a semi-circlar leading edge with four rows of laterally-inclined film cooling orifices positioned symmetrically about the stagnation line. The computational domain follows the physical domain and includes the curved blade surface as well as the coolant regions in the circular coolant orifices. The injection orifices are inclined spanwise at 30° to the blade surface. A multi-zone curvilinear grid is used to simulate the complex configuration. Grids are generated by a block-structured elliptic grid generation method which represents exactly the curved blade surface as well as the circular injection orifices. Computations over the cooled turbine blade model are carried out for overall mass flow ratios of 0.52 and 0.97. The relative mass flow ratios from each orifice are specified to match experimental values. Density ratios of coolant to free stream were taken to be unity (constant density). Comparison of predicted film cooling effectiveness with experimental data showed reasonable agreement.
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Jung, Alexander R., Jürgen F. Mayer, and Heinz Stetter. "Simulation of 3D-Unsteady Stator/Rotor Interaction in Turbomachinery Stages of Arbitrary Pitch Ratio." In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-069.
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This paper presents a computational method for the calculation of unsteady three-dimensional viscous flow in turbo-machinery stages. The method is based on a Finite-Volume Navier-Stokes solver for structured grids in a multiblock topology. The meshes at the stator/rotor interface are overlapped by two grid cells. An implicit residual smoothing method applicable to global time-stepping is used to accelerate the solution process. The problem of periodic boundary treatment for unequal pitches is handled using a method of time-inclined computational domains for three dimensions. The method applies a time transformation to the stator domain and to the rotor domain and uses different time-steps in the two domains. The results of a numerical simulation of the flow in a transonic turbine stage with a pitch ratio of 1.364 are presented. The time-averaged solution is compared to experimental data and satisfactory agreement is stated. Complex 3D-unsteady flow phenomena (shock motion, vortex shedding) are observed. Unsteady blade pressure fluctuations at various positions in spanwise direction are shown and the fluctuations are found to vary considerably along span. Instantaneous distributions of static pressure, Mach number, and entropy are presented.
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Dubrovskii, Vitalii, Aleksei Podvysotskii, Aleksandr Shraiber, Yaroslav Chudnovsky, and Aleksandr Kozlov. "Heat Transfer Between Liquid Film Formed on the Inclined Dimpled Surface and Ambient Air." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65042.
Full textAbstract:
Heat transfer enhancement area attracts the close attention of the researchers and engineers worldwide for the last decades. The most popular techniques nowadays to enhance heat transfer from the surface is to extend it with the fins, studs, etc. or to profile it with the elements of artificial roughness, winglets, dimples, etc. Those types of surface enhancement allow improving the thermal efficiency of the heat transfer equipment with minimal design modification and without significant capital expenses. One of the interesting and promising techniques of the surface profiling is the formation on the surface the arrangement of spherical dimples, which generate intensive vortex structure near the surface, increase flow turbulence and, as a result, enhance heat and mass transfer between a profiled surface and a liquid (or gas) flowing over it [1–3]. In this connection, it is interesting to establish whether surface profiling will also enhance the heat transfer intensity between a liquid film on such a surface and ambient air. Unfortunately, authors were not able to find any publications on this subject in the open domain. At the same time, the investigation of this process could be of great interest for the engineering practice, in particular, for the cooling towers advancement. In the present work, the authors discuss some experimental results obtained for the different profile parameters and flow regimes.
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Ma, Sang-Bum, and Kwang-Yong Kim. "Aerodynamic Performances of a Centrifugal Compressor With Discrete Cavities." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63535.
Full textAbstract:
In this study, aerodynamic performance of the centrifugal compressor was investigated by using a recirculating device called discrete cavities. A parametric study was conducted using six parameters related to the geometry of the discrete cavities, i.e., the inclined angle, the port angle and width, the length of cavity, the axial location of each cavity, and the number of cavities. Three-dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model were used for aerodynamic analysis of the centrifugal compressor with discrete cavities. The hexahedral grid was used in impeller domain and tetrahedral grid was used in volute and inclined discrete cavities. The numerical results for the adiabatic efficiency and the total pressure ratio (inlet to outlet) showed good agreements with experimental data. It was found that inclination of the discrete cavities further increased the stall margin without loss of efficiency compared to the uninclined discrete cavities.