Academic literature on the topic 'The cloven viscount'
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Journal articles on the topic "The cloven viscount"
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Ferraz, Bruna Fontes, and Claudia Cristina Maia. "Partido: a página virada de Italo Calvino / Partido: Italo Calvino’s Turned Page." O Eixo e a Roda: Revista de Literatura Brasileira 28, no. 3 (2019): 65. http://dx.doi.org/10.17851/2358-9787.28.3.65-82.
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Resumo: Este artigo tem por objetivo apresentar uma análise de Partido, espetáculo teatral do grupo Galpão, de Belo Horizonte, concebido a partir do romance O visconde partido ao meio, de Italo Calvino. Com dramaturgia de Cacá Brandão e direção de Cacá Carvalho, o espetáculo, tratado aqui como uma tradução da obra do escritor italiano, contribuiu para a recepção de Calvino no Brasil. Do texto para o palco, houve um trabalho de transformação que permitiu ao Galpão ir além do livro de Calvino, em alguma medida rompendo com ele. A palavra escrita traduziu-se em uma linguagem que privilegiou o corpo e as experiências de vida dos atores. A tradução foi lida a partir do pensamento de Walter Benjamin, Paul Ricouer e Haroldo de Campos, ressaltando o trabalho do grupo mineiro como uma poética de tradução pautada na produção da diferença.Palavras-chave: O visconde partido ao meio; tradução; teatro; grupo Galpão.Abstract: This paper aims to present an analysis of the play Partido, performed by the theatrical group Galpão, from Belo Horizonte, and conceived from the novel The cloven viscount, by Italo Calvino. With dramaturgy by Cacá Brandão and directed by Cacá Carvalho, the show, perceived here as a translation of Calvino’s work, contributed to the reception of the italian writer in Brazil. From the text to the stage, creators worked on transforming the original text in such a way that allowed Galpão to surpass the book, subverting it in some way. The written word was translated into a language that favored actors’ bodies and life experiences. The translation was analyzed from the thoughts of Walter Benjamin, Paul Ricouer and Haroldo de Campos, highlighting the Minas Gerais group work as a poetic translation based on the production of the different.Keywords: The cloven viscount; translation; theater; Galpão group.
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Beckebanze, F., C. Brouzet, I. N. Sibgatullin, and L. R. M. Maas. "Damping of quasi-two-dimensional internal wave attractors by rigid-wall friction." Journal of Fluid Mechanics 841 (February 26, 2018): 614–35. http://dx.doi.org/10.1017/jfm.2018.107.
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The reflection of internal gravity waves at sloping boundaries leads to focusing or defocusing. In closed domains, focusing typically dominates and projects the wave energy onto ‘wave attractors’. For small-amplitude internal waves, the projection of energy onto higher wavenumbers by geometric focusing can be balanced by viscous dissipation at high wavenumbers. Contrary to what was previously suggested, viscous dissipation in interior shear layers may not be sufficient to explain the experiments on wave attractors in the classical quasi-two-dimensional trapezoidal laboratory set-ups. Applying standard boundary layer theory, we provide an elaborate description of the viscous dissipation in the interior shear layer, as well as at the rigid boundaries. Our analysis shows that even if the thin lateral Stokes boundary layers consist of no more than 1 % of the wall-to-wall distance, dissipation by lateral walls dominates at intermediate wave numbers. Our extended model for the spectrum of three-dimensional wave attractors in equilibrium closes the gap between observations and theory by Hazewinkel et al. (J. Fluid Mech., vol. 598, 2008, pp. 373–382).
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LITTLE, PATRICK. "THE IRISH ‘INDEPENDENTS’ AND VISCOUNT LISLE’S LIEUTENANCY OF IRELAND." Historical Journal 44, no. 4 (2001): 941–61. http://dx.doi.org/10.1017/s0018246x01001972.
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This article examines the influence of a distinct Irish Protestant faction on parliamentarian policy-making in the mid-1640s – the Irish Independents. These men were not merely clients of parliament’s lord lieutenant, Viscount Lisle, but formed a group with consistent personnel and policies, which can be traced back to the ‘Boyle group’ in the Irish council of the 1620s and 1630s. In the 1640s they came into an alliance with the English Independents, based on common hostility to the Presbyterian party, the Scots, and the supporters of Ormond and Inchiquin in Ireland. This coalition was, however, inherently unstable. Faced with equivocation at Westminster, where Ireland had always been low on the list of priorities, from December 1646 the Irish Independents were forced to take charge of parliament’s Irish policy, and many of the initiatives previously attributed to Lisle in 1646–7 can more properly be laid at their door. In conclusion, it is suggested that the Irish Independents represent a radical strain in Irish Protestantism, which supported Ireland’s closer integration into an ‘English Empire’, and which would see its fulfilment in the unionist agenda developed in the 1650s.
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Gómez-González, Manuel, and Juan C. del Álamo. "Flow of a viscous nematic fluid around a sphere." Journal of Fluid Mechanics 725 (May 14, 2013): 299–331. http://dx.doi.org/10.1017/jfm.2013.156.
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AbstractWe analyse the creeping flow generated by a spherical particle moving through a viscous fluid with nematic directional order, in which momentum diffusivity is anisotropic and which opposes resistance to bending. Specifically, we provide closed-form analytical expressions for the response function, i.e. the equivalent to Stokes’s drag formula for nematic fluids. Particular attention is given to the rotationally pseudo-isotropic condition defined by zero resistance to bending, and to the strain pseudo-isotropic condition defined by isotropic momentum diffusivity. We find the former to be consistent with the rheology of biopolymer networks and the latter to be closer to the rheology of nematic liquid crystals. These ‘pure’ anisotropic conditions are used to benchmark existing particle tracking microrheology methods that provide effective directional viscosities by applying Stokes’s drag law separately in different directions. We find that the effective viscosity approach is phenomenologically justified in rotationally isotropic fluids, although it leads to significant errors in the estimated viscosity coefficients. On the other hand, the mere concept of directional effective viscosities is found to be misleading in fluids that oppose an appreciable resistance to bending. Finally, we observe that anisotropic momentum diffusivity leads to asymmetric streamline patterns displaying enhanced (reduced) streamline deflection in the directions of lower (higher) diffusivity. The bending resistance of the fluid is found to modulate the asymmetry of streamline deflection. In some cases, the combined effects of both anisotropy mechanisms leads to streamline patterns that converge towards the sphere.
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Wang, C. Y. "Hydrodynamic Disk Braking." Journal of Applied Mechanics 52, no. 2 (1985): 263–66. http://dx.doi.org/10.1115/1.3169038.
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A viscous fluid separates a rotating disk and a parallel nonrotating disk. As the two disks are squeezed closer together, increased viscous torque is transmitted to the rotating disk. The Navier-Stokes equations are solved using a perturbation in the small squeeze number. Two cases of squeezing are studied: constant velocity approach and constant force approach.
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Das, S. K., and S. N. Das. "Modeling of Coupled Roll and Yaw Damping of a Floating Body in Waves." Mathematical Problems in Engineering 2007 (2007): 1–17. http://dx.doi.org/10.1155/2007/96373.
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A mathematical model is described to investigate the damping moment of weakly nonlinear roll and yaw motions of a floating body in time domain under the action of sinusoidal waves. The mathematical formulation for added mass moment of inertia and damping is presented by approximating time-dependent coefficients and forcing moments when small distortion holds. Using perturbation technique, we obtain orderwise equations wherein the closed-form solution is obtained for zeroth-order case, and for higher-order cases we resort to numerical integration using Runge-Kutta method with adaptive step-size algorithm. In order to analyze the model result, we perform numerical experiment for a vessel of 19190 tons under the beam wave of 1 m height and frequency 0.74 rad/s. Closer inspection in damping analysis reveals that viscous effect becomes significant for roll damping; whereas for yaw damping, contribution from added mass variation becomes significant.
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MYUNG, Y. S., B. H. CHO, YONGDUK KIM, and YOUNG-JAI PARK. "INFLATIONARY UNIVERSE IN SUPERSTRING THEORIES." Modern Physics Letters A 01, no. 03 (1986): 175–82. http://dx.doi.org/10.1142/s0217732386000257.
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We show that there are two non-equilibrium regions due to the inhomogeneous massive modes of the closed strings. The first region (T0<T<Tc) is more viscous and is dominated by the bulk viscosity. The second region (Te≤T≤T0) is less viscous and is described by the shear viscosity. In the less viscous region, considering the shear viscosity due to the transport of gravitational radiation, the large entropy may be produced owing to the inflation of 3-dimensional space and collapse of internal space.
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Bratsun, Dmitry, and Vladimir Vyatkin. "Closed-Form Non-Stationary Solutionsfor Thermo and Chemovibrational Viscous Flows." Fluids 4, no. 3 (2019): 175. http://dx.doi.org/10.3390/fluids4030175.
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A class of closed-form exact solutions for the Navier–Stokes equation written in the Boussinesq approximation is discussed. Solutions describe the motion of a non-homogeneous reacting fluid subjected to harmonic vibrations of low or finite frequency. Inhomogeneity of the medium arises due to the transversal density gradient which appears as a result of the exothermicity and chemical transformations due to a reaction. Ultimately, the physical mechanism of fluid motion is the unequal effect of a variable inertial field on laminar sublayers of different densities. We derive the solutions for several problems for thermo- and chemovibrational convections including the viscous flow of heat-generating fluid either in a plain layer or in a closed pipe and the viscous flow of fluid reacting according to a first-order chemical scheme under harmonic vibrations. Closed-form analytical expressions for fluid velocity, pressure, temperature, and reagent concentration are derived for each case. A general procedure to derive the exact solution is discussed.
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ROOS, P. C., and H. M. SCHUTTELAARS. "Horizontally viscous effects in a tidal basin: extending Taylor's problem." Journal of Fluid Mechanics 640 (October 27, 2009): 421–39. http://dx.doi.org/10.1017/s0022112009991327.
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The classical problem of Taylor (Proc. Lond. Math. Soc., vol. 20, 1921, pp. 148–181) of Kelvin wave reflection in a semi-enclosed rectangular basin of uniform depth is extended to account for horizontally viscous effects. To this end, we add horizontally viscous terms to the hydrodynamic model (linearized depth-averaged shallow-water equations on a rotating plane, including bottom friction) and introduce a no-slip condition at the closed boundaries.In a straight channel of infinite length, we obtain three types of wave solutions (normal modes). The first two wave types are viscous Kelvin and Poincaré modes. Compared to their inviscid counterparts, they display longitudinal boundary layers and a slight decrease in the characteristic length scales (wavelength or along-channel decay distance). For each viscous Poincaré mode, we additionally find a new mode with a nearly similar lateral structure. This third type, entirely due to viscous effects, represents evanescent waves with an along-channel decay distance bounded by the boundary-layer thickness.The solution to the viscous Taylor problem is then written as a superposition of these normal modes: an incoming Kelvin wave and a truncated sum of reflected modes. To satisfy no slip at the lateral boundary, we apply a Galerkin method. The solution displays boundary layers, the lateral one at the basin's closed end being created by the (new) modes of the third type. Amphidromic points, in the inviscid and frictionless case located on the centreline of the basin, are now found on a line making a small angle to the longitudinal direction. Using parameter values representative for the Southern Bight of the North Sea, we finally compare the modelled and observed tide propagation in this basin.
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Evatt, Geoffrey W. "Röthlisberger channels with finite ice depth and open channel flow." Annals of Glaciology 56, no. 70 (2015): 45–50. http://dx.doi.org/10.3189/2015aog70a992.
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AbstractThe theoretical basis of subglacial channel dynamics can be traced back to the work of Röthlisberger (1972) and Nye (1953). Röthlisberger (1972) considered the channels’ behaviour to be governed by a mix between water friction melting back the channel walls and the viscous closure of the surrounding ice; Nye (1953) derived a viscous closure rate for the ice. While their modelling is evidently well constructed, two aspects of their work have gone undeveloped. The first is the consideration of a finite glacier depth within the viscous closure law, instead of the assumption of an infinite glacier depth. The second is the allowance of a region of open channel flow, so that a channel’s water may transition from a region of closed channel flow to one where the water is exposed to the atmosphere. This paper helps close these two gaps, showing how Nye’s equation for the rate of ice closure can be modified, and how the point of transition between closed and open channel flow may be determined.
Dissertations / Theses on the topic "The cloven viscount"
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Villa, Stefano. "Behaviour of a Colloid close to an Air-Water Interface : Interactions and Dynamics." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS074/document.
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Malgré un rôle important en physique, biologie et dans les processus industriels tels l’agroalimentaire et la dépollution de l’eau, la dynamique d'une particule colloïdale à proximité d'une interface fluide et ses interactions avec l’interface sont des phénomènes physiques encore débattus.Dans cette thèse, nous explorons la dynamique et l'interaction de particules colloïdales individuelles à proximité d'une interface air-eau à l’équilibre thermique.Afin de mener cette étude sans perturber le système expérimental, nous avons conçu et construit un microscope interférentiel à double onde adapté à l'interface air-eau. Contrairement à d'autres techniques expérimentales, notre configuration permet la mesure précise de la distance absolue entre particule l'interface sans nécessiter d’étalonnage ou d’hypothèse sur l'emplacement de l'interface. Nous avons ainsi pu obtenir des trajectoires hautement résolues de particules en 3D proches de l'interface, permettant la mesure précise des diffusions proche de l’interface et des interactions particules-interface.Le système montre deux profils d’énergie potentielle différents. Deux distances d’équilibre particule-interface sont ainsi observées. La plus grande peut être expliquée par la compétition des interactions de Van der Waals et électrostatiques avec la pesanteur. La distance d’équilibre plus courte ne peut s’expliquer que par la présence d’une interaction attractive supplémentaire. Les origines possibles de cette interaction sont discutées.En utilisant une nouvelle méthode d'analyse des déplacements quadratiques moyens des particules dans un potentiel générique, nous avons pu accéder aux coefficients de friction visqueuse des particules en fonction de la distance à l'interface. De manière singulière, l’interface air-eau se comporte comme une paroi liquide pour le mouvement des particules parallèlement à l’interface et comme une paroi solide pour le mouvement des particules perpendiculaire à l’interface. Ce résultat expérimental peut être partiellement rationalisé en considérant des modèles récents basés sur l’incompressibilité de surface. Cependant, certaines différences entre les expériences et les théories demeurent. Les coefficients de friction visqueuse sont plus importants que les prédictions hydrodynamiques et dépendent de la charge électrique des particules, ce qui suggère un possible rôle des phénomènes électrocinétiques.Enfin, le piégeage des particules à l'interface air-eau et leur angle de contact ont été mesurés tout en modifiant la force ionique de la solution aqueuse et en faisant varier l‘état de surface des colloïdes<br>Despite the relevance to environmental, biological and industrial processes, the motion of a colloidal particle close to a fluid interface and the way it interacts with the water surface are still largely elusive and intriguing physical phenomena.In this thesis, we explore the motion dynamics and the interaction of individual colloidal particles close to an air-water interface in thermal equilibrium.In order to investigate them without perturbing or altering the experimental system, we designed and built a dual-wave reflection interference microscope working with an air-water interface geometry. Contrary to other established experimental techniques, our set-up allows accurate measurements of the absolute particle-interface distance and thus does not require any calibration or assumption to know the location of the interface. Highly resolved 3D particle trajectories close to the interface were obtained, from which information on particle diffusion close to the interface and particle-interface interactions are obtained.The system shows two different potential energy landscapes resulting in two different equilibrium particle-interface distances. The larger one can be fairly explained by Van der Waals and electrostatic interactions combined with gravity. The shorter one highlights the existence of an unexpected additional attractive interaction. The possible origins of such an interaction are discussed.Using a method of analysis of the particle mean square displacements in a generic potential we developed, we were able to access to particle drag coefficients as a function of the distance from the interface. Peculiarly, the air-water interface acts as a slip boundary for the particle motion parallel to the interface and as a no-slip boundary for the particle motion perpendicular to the interface. This experimental result can be partially rationalized considering recent models based on surface incompressibility. However, some discrepancies between experiments and theories remain. Experimental drag coefficients are larger than the hydrodynamic predictions and depend on the particle electrical charge, pointing therefore to a possible role of electrokinetic phenomena.Finally, the particle trapping at the air-water interface and its contact angle were observed while tuning the ionic strength of the aqueous solution and varying the surface state of the colloids
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Abdul, Hamid Nor Hayati. "Seismic damage avoidance design of warehouse buildings constructed using precast hollow core panels." Thesis, University of Canterbury. Civil Engineering, 2006. http://hdl.handle.net/10092/1153.
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Precast prestressed hollow core units are commonly used in the construction of the flooring system in precast buildings. These units without transverse reinforcement bars are designed to resist seismic loading as replacement for fixed-base precast wall panels in the construction of warehouse buildings. Thus, this research seeks to investigate the seismic performance of the units constructed as a subassemblage (single wall) subjected to biaxial loading and as a superassemblage (multi-panel) subjected to quasi-static lateral loading. A design procedure for warehouse building using precast hollow core walls under Damage Avoidance Design (DAD) is proposed. In addition, a risk assessment under Performance-Based Earthquake Engineering (PBEE) is evaluated using the latest computational tool known as Incremental Dynamic Analysis (IDA). A comparative risk assessment between precast hollow core walls and fixed-base monolithic precast wall panels is also performed. Experimental results demonstrate that rocking precast hollow core walls with steelarmouring do not suffer any non-structural damage up to 2.0% drift and minor structural damage at 4.0% drift. Results revealed that the wall with unbonded fuse-bars and 50% initial prestressing of unbonded tendons performed the best compared with other types of energy dissipators. Furthermore, 12mm diameter of fuse-bar is recommended as there is no uplifting of the foundation beam during ground shaking. Hence, this type of energy dissipator is used for the construction of seismic wall panels in warehouse buildings. One of the significant findings is that the capacity reduction factor (Ø ) which relates to global uncertainty of seismic performance is approximately equal to 0.6. This value can be used to estimate the 90th percentile of the structures without performing IDA. Therefore, the structural engineers are only required to compute Rapid-IDA curve along with the proposed design procedure.
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Marcin, Sarah Elizabeth. "Leprosy and social exclusion in Italo Calvino’s Il visconte dimezzato and Umberto Eco’s Il nome della rosa." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-2855.
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The leper is the ultimate symbol of the social outcast. Plagued by connotations of not just contagion but of sinfulness and moral depravity, lepers have long been stigmatized and excluded from society. The Hebrew Bible declared them to be unclean, and their influence was believed to be wholly corrupting, as if their physical deformities were an external sign of their defiled souls. In the Middle Ages, those diagnosed with leprosy were made to undergo a particularly severe ritual that closely resembled the office of the dead, making them effectively dead to the world. They were then isolated from the healthy population in leprosariums, and their movements and behaviors were strictly controlled. However, their exclusion can be seen as serving a larger purpose than just the protection of normal society from infection in that it can be used by those in power as a mechanism of social control. The imputation of danger to undesirable persons of a given community ensures that they will be duly feared and ostracized. It is within this context that Italo Calvino and Umberto Eco make use of the idea of the leper as a social outlier in their novels, Il visconte dimezzato and Il nome della rosa, as a way to critique certain processes of exclusion, namely the construction and stigmatization of a social “other” as a means of maintaining social order. This report draws on the historical and literary treatments of the leper to discuss the ways in which Calvino and Eco successfully employ the image of the leper to represent the machinery of exclusion and to shed light on the continued marginalization of outcast groups down to the present day.<br>text
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Jih, Cheng Yuh, and 紀承育. "Viscous Flow Past a Cylinder Close to a Plane--- ---Physical Experiment." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/85968764291420925431.
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碩士<br>逢甲大學<br>土木及水利工程研究所<br>81<br>Physical experiments were performed to study the viscous flow
with or without density variation past a cylinder close to a
horizontal plane. A tank was filled up with water of uniformde
nsity orsaline water with linear density gradient. Then the
cylinder and the plane in the tank were pulled at a
constantspeed to simulate the relative motion. Camera and
video tapewere moved together withthe cylinder and the plane
for recording.It was shown by the experiments that:1.The main
flow is upraised after passing the cylinder, and the velocity
of the gap flow is decresing with time, and the separation
region and the blocking region attached to the plane are
appeared in the transient flow. 2. Atsmaller gap distance the
appearance times of the separationregion of the cylinder and
the blocking region of the plane areearlier, and the
jumpingheight of the gap flow is larger 3.Thecombination of the
main flow and the gap flow, and thedevelopment of separation
region of the plane were easier at highReynolds Number. 4.The
main flow in density stratifiedcondition drop faster behind
thecylinder, and the gap flow risemore rapidly than in density
uniform condition. Both productsoscillatory internal wave, and
makes the separation region of the cylinder slowly develop.
The blocking region of the plane is notevident. On the
contrary, the separation region of the planedevelops faster,
and has larger scale.
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Huang, Tsung Liang, and 黃宗良. "Viscous Flow Past a Cylinder Close to a Plane -- Numerical Model." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/73044856270402430791.
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碩士<br>逢甲大學<br>土木及水利工程研究所<br>81<br>In this paper, a special 2D field of viscous transient flow
past a circular cylinder close to a planewas studied. A
horizontal plane (line) was used as thelower boundaryof the
field , and a circular cylinder (circle) was place near and
above the plane with a "gap"between the cylinder and the
plane. Two numericalmodels has been used in this paper. The
first one was incompressible flow model. Body-fitted
coordinate systemand finite difference method were adopted for
thedevelopmentof the model. Since this model was divergedas
the cylinder was very closed to the plane, the secondmodel was
developed, i.e.compress- -ible flow model.Results showed that:
1) main flow is upraise as it passesthe cylinder; the velocity
of the gap flow is decreasing with time; the separation region
of the cylinder and theplane boundary are appeared; the lift
coefficient wastowared a periodic configuration; the drag
coefficient isincreasingslowly. 2) At the small distance of
the gap,the flow field iseasier to steady state; the scale
ofthe separation on the cylinder and the plane is biggerthan
others; the drag and the lift coefficient is increasing
rapidly. 3) In different Reynold numbers,the flow field is
similar; the separation on the planeis increasing with time;
the drag and the liftcoefficient is incressing with time, and
the value ofsmall Reynold number is bigger than others.
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Tsai, Chih-Yuan, and 蔡知原. "Medical image registration using a closed incompressible viscous fluid model with mutual information." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/92981112037696663209.
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碩士<br>國立臺灣大學<br>工程科學及海洋工程學研究所<br>100<br>Image registration is very important for a wide variety of medical image applications. It provides lots of image information for medical personnel to judge and analyze the anatomical structures and lesions. There are many image registration method being proposed. This thesis describes a non-rigid viscous model which involves a complicated, nonlinear partial differential equation. We propose to use the closed two-dimensional incompressible viscous flow model to solve the partial differential equation, We also incorporate the knowledge of mutual information into the model, from which the velocity and displacement fields are obtained. A wide variety of magnetic resonance images were used to evaluate this new method. Experimental results indicate that the proposed method successfully performed registration and provided good accuracy. Comparing to the optical-flow model, our method produced higher correlation coefficient scores. We believe that our algorithm is of potential in a wide variety of medical image registration applications.
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Chao, Yu-Hsuan, and 趙祐萱. "Volumetric Medical Image Registration Using a Three Dimension Closed Incompressible Viscous Fluid Model." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/m47385.
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碩士<br>國立臺灣大學<br>工程科學及海洋工程學研究所<br>105<br>Image registration is very important for a wide variety of image processing applications in engineering and medicine. It provides lots of precious information for further analysis in many fields. Image registration is the process of transforming different images into one coordinate system. We propose a three-dimensional closed incompressible viscous fluid image registration algorithm and develop its numerical methods. The core component of solving the viscous fluid model is the partial differential equations (PDEs). The common way to solve the PDF is approximating it using the finite second order differential followed by the Cholesky algorithm to solve the linear formulas. However, the computation complexity will be tremendous and the memory usage will be unbearable. In addition, if the template image has vertical-direction deformation, the two-dimensional method will not be able to handle this situation. We employ the alternating-direction implicit (ADI) and Hopscotch as the numerical methods to solve the PDE of the three-dimensional viscous fluid model. A wide variety of magnetic resonance images were used to evaluate this new method. Experimental results indicated that the proposed method not only successfully performed registration but also provided excellent accuracy. The computation time and the memory usage have been dramatically reduced as well.
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Chang, Ching-Yu, and 張境畬. "Accelerated Multimodal Medical Image Registration Based on a Closed Incompressible Viscous Fluid Model." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3wh72u.
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碩士<br>國立臺灣大學<br>工程科學及海洋工程學研究所<br>105<br>Image registration is an important technique for medical research and medical diagnosis. It is a process of looking for a spatial transformation between two images and mapping one to the other one based on the transformation function. There are many image registration methods and one algorithm is based on a non-rigid fluid flow model. However, the computation of the governing equation and Gaussian smoothing of this method is quite time-consuming and it is unable to perform multimodal registration. To address these problems, we adopt the Jacobi method iteratively to solve the implicit viscosity terms and parallelize the program with GPU. Compute Unified Device Architecture (CUDA), an application programming interface for GPU by NVIDIA, is used to accelerate the algorithm. Besides, we modify the body force term via the mutual information to achieve multimodal image registration. A variety of different types of magnetic resonance images were used to evaluate this new method. Experimental results indicated that the proposed method efficiently registered many kinds of images, including skull-stripping images, noisy images, large scale deformation images and multimodal images. Comparing to the previous fluid-flow model, our method approximately reduced the processing time by half and successfully achieved multimodal image registration.
Books on the topic "The cloven viscount"
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Calvino, Italo. Our ancestors: Three novels, The cloven viscount, Baron in the trees, The non-existent knight. Minerva, 1992.
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Calvino, Italo. Cloven Viscount. Houghton Mifflin Harcourt Trade & Reference Publishers, 2012.
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Balogh, Mary. Simply Magic: On a splendid August afternoon Susanna Osbourne is introduced to the most handsome man she has ever seen . . . and instantly feels the icy chill of recognition. Peter Edgeworth, Viscount Whitleaf, is utterly charming—and seemingly unaware that they have met before. With his knowing smile and seductive gaze, Peter acts the rake; but he stirs something in Susanna she has never felt before, a yearning that both frightens and dazzles her. Instantly she knows: this brash nobleman poses a threat to her heart . . . and to the secrets she guards so desperately. From the moment they meet, Peter is drawn to Susanna’s independence, dazzled by her sharp wit—he simply must have her. But the more he pursues, the more Susanna withdraws . . . until a sensual game of thrust-and-parry culminates in a glorious afternoon of passion. Now more determined than ever to keep her by his side, Peter begins to suspect that a tragic history still haunts Susanna. And as he moves closer to the truth, Peter is certain of one thing: he will defy the mysteries of her past for a future with this exquisite creature—all Susanna must do is trust him with the most precious secret of all. . . . Delacorte Press, 2007.
Find full textBook chapters on the topic "The cloven viscount"
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Alauzet, F., and D. Marcum. "A Closed Advancing-Layer Method with Changing Topology Mesh Movement for Viscous Mesh Generation." In Proceedings of the 22nd International Meshing Roundtable. Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-02335-9_14.
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Gander, Martin J., Laurence Halpern, and Veronique Martin. "How Close to the Fully Viscous Solution Can One Get with Inviscid Approximations in Subregions ?" In Lecture Notes in Computational Science and Engineering. Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-11304-8_26.
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Churchill, Stuart Winston. "Exact, Closed-Form Solutions of the Equations of Motion." In Viscous Flows. Elsevier, 1988. http://dx.doi.org/10.1016/b978-0-409-95185-1.50019-x.
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Kennel, Charles F. "The Viscous Magnetosphere." In Convection and Substorms. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195085297.003.0007.
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This chapter describes how the magnetosphere is shaped by the tangential shear stress exerted at the magnetopause by collisionless viscosity. In Section 4.2, we discuss the low-latitude boundary layer (LLBL), which contains plasma of solar wind origin that has been transported across the magnetopause current layer. The velocity shear in the LLBL drives field-aligned currents into the ionosphere on the morning side and out of the ionosphere on the evening side (Section 4.3). These currents are of the appropriate sense to drive two-cell convection in the highlatitude ionosphere. The footprint of the LLBL in the ionosphere to which the field aligned currents connect is clearly identifiable by its characteristic particle precipitation (Section 4.4). The shear in the LLBL also generates 1-20 mHz PC 4- 5 micropulsations whose polarizations, tailward propagation, and phase speeds are consistent with the Kelvin-Helmholtz (K-H) instability (Section 4.5). The K-H vortices may couple to “vortex auroras” in the local afternoon sector of the auroral oval (Section 4.6). Vortex auroral dissipation may be responsible for a morningevening asymmetry in the viscous interaction and its manifestations. Organized vortical flows have been observed not only next to the magnetopause, but also near the center of the plasma sheet, accompanied by local quasiperiodic magnetic field oscillations and PC 5 micropulsations on the ground (Section 4.7). In Section 4.8, we discuss observations of a thick boundary layer flow on closed field lines next to the magnetopause 220 RE downstream. This puts us in a position to estimate the rates of particle and energy injection into the magnetosphere due to the viscous interaction (Section 4.9). Spacecraft crossings of the magnetopause last from a few seconds to a few minutes and are characterized by a rapid, distinct rotation of the magnetic field and striking changes in plasma density, pressure, flow velocity, composition, and energetic particle distribution (Williams, 1979a; 1980; Williams et al., 1979). A broader boundary layer lies just inside the magnetopause. The so-called low-latitude boundary layer was first identified at 18 RE radial distance in the magnetotail using Vela 4B (Hones et al., 1972) and Vela 5 and 6 (Akasofu et al., 1973b) low-energy plasma measurements.
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Kennel, Charles F. "Convection For Northward Interplanetary Field." In Convection and Substorms. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195085297.003.0013.
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Besides common sense, a number of results suggest that we can learn more about the slow “viscous” flow state by studying the magnetosphere during northward interplanetary field conditions. In particular, statistical studies have consistently identified a “residual” state of magnetospheric and ionospheric convection in northward field conditions. The integrated potential across the high latitudeionosphere does not drop below a certain resting value of about 20 kV even when the interplanetary field has been due north for several hours. There appears to be a similar residual component of geomagnetic activity that is independent of the direction of the interplanetary field (Scurry and Russell, 1991). Its correlation with the dynamic pressure of the solar wind strengthens our suspicion that it is related to viscosity. Will we be able to prove the convection in this residual state is driven by viscosity? Does the flow in northward field conditions resemble the underlying irregular flow state of the plasma sheet found at other times? Does the magnetosphere approach the teardrop configuration during prolonged intervals of northward interplanetary field? These are but a few of the questions that whet our interest in convection during northward field conditions. One does not arrive at the state of pure viscous convection immediately after the interplanetary field swings northward. Dungey (1963) was the first of many to argue that a northward magnetosheath field line will reconnect with an open tail lobe field line to create one that is connected to the ionosphere at one end and draped over the dayside magnetopause at the other. The sudden reconfiguration of stress will lead to sunward convection on the newly reconnected field lines. In the ionosphere, this superposes a “reverse” two-cell convection pattern in the central polar cap upon the two “direct” convection cells. If and when the draped reconnected field line finds a partner in the opposite tail lobe with which to reconnect, a newly closed field line will form. Dungey had imagined that the same magnetosheath field line would reconnect simultaneously with both tail lobes, in which case the rate at which open magnetic flux is closed depends upon the rate of tail-lobe reconnection.
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Lovejoy, Shaun. "What have we done?" In Weather, Macroweather, and the Climate. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190864217.003.0010.
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It was April 11, 2014, and the McGill University press release went online at 1:30 in the afternoon. Although I’d published many articles, they were on fundamental geoscience; the release summarized the first one that had significant social and political consequences. Its title, “Scaling Fluctuation Analysis and Statistical Hypothesis Testing of Anthropogenic Warming,” was arcane, but the release was clear enough: “Statistical analysis rules out natural- warming hypothesis with more than 99% certainty” (the article, published in Climate Dynamics, is hereafter referred to as CD). It had been fifteen months since the original submission went to peer review, but now the pace picked up dramatically. Within hours, the tone was set by the skeptic majordomo Viscount Christopher Monckton of Brenchely, who displayed his Oxbridge classics erudition by deliciously qualifying the paper as a “mephitically ectoplasmic emanation from the Forces of Darkness.” Three days later, with the release getting 12,000 hits per day, the “Friends of Science” sent an aggressive missive to the McGill chancellor asking that it be removed from McGill’s site. The Calgary- based group with its Orwellian name was set up in 2002 to promote the theory that “The sun is the driver of climate change. Not you. Not CO2.” (Fig. 6.1). One could understand their thunder. Rather than trying to prove that the warming was anthropogenic— something that is impossible to do “beyond reasonable doubt”— the new paper closed the debate2 by doing something far simpler: by disproving the “Friends” Giant Natural Fluctuation (GNF) hypothesis. If we exclude either divine or extraterrestrial intervention, then the warming is natural or it is human; there is no third alternative. The skeptics were stuck. To add insult to injury, their prepackaged sermons on the inadequacies of computer models or their speculations about solar variability were irrelevant. Provoked by the media attention and several Op- Eds in the hours, days, and weeks that followed, in email, blogs, and Twitter, I was treated to a deluge of abuse: “atheist,” “Marxist,” “hippy name,” and so on— everything, it seemed, short of death threats.
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Srinivasa Rao, P. "Direct Numerical Simulation of Nano Channel Flows at Low Reynolds Number." In Direct Numerical Simulations - An Introduction and Applications [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94949.
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The governing equations of viscous fluid flow are generally represented by Navier–Stokes (NS) equations. The output of Navier Stokes equations is in essence velocity vector from which rest of the flow parameters can be calculated. It is essentially a riotous task, sometimes it becomes so unmanageable that fluid flow over simplest topologies under low Reynold’s numbers also needs the most powerful supercomputing facility to solve, if needed to model the fluid and its behavior under the turbulent conditions the best way out is to solve the averaged NS equations. However in the process of averaging Reynolds introduced certain new terms such as Reynolds Stresses. Therefore it is required to close the system of equations by relating the unknown variables with known ones. Hence we have turbulence models. Direct Numerical Simulation (DNS) is a method of solving NS equations directly that is by forfeiting the need of turbulence models as the equations are not averaged. However originally direct numerical simulation procedure does not need of additional closure equations, it is essential to have very fine grid elements and should be estimated for exceptionally small time steps to achieve precise solutions. In the present chapter an interesting flow through nano-channel problem has been discussed using the indispensable mathematical technique of computational fluid dynamics (CFD) which is DNS.
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Kennel, Charles F. "The Reconnecting Magnetosphere." In Convection and Substorms. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195085297.003.0008.
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Dungey’s (1961a) pattern of internal magnetospheric convection was similar to that of Axford and Hines (1961). However, his model made testable statements about the structure of the magnetosphere that were not contained in the viscous convection model. It predicted that solar wind plasma enters the magnetosphere over the polar caps, that open field lines connect the polar caps directly to the interplanetary magnetic field, and that these field lines are stretched into a long, low-density magnetic tail. There would be a current layer separating the two lobes of the tail, and surrounding it, a sheet of relatively dense, hot, earthward-convecting plasma confined by closed field lines. A second magnetic neutral line would terminate the earthward flow region (Levy et al., 1964; Axford et al., 1965; Petschek, 1966; Axford, 1969). To preserve the steady state, reconnection at the tail neutral line had to have the same rate as at the dayside magnetopause. Clearly, the two reconnection regions ought to be major drivers of magnetospheric activity. Yet unambiguous proof of the existence of magnetopause reconnection was not found until 1979, 18 years after the reconnection model was proposed, and no one knew where to look for tail reconnection, because Dungey’s model did not say how far away the tail neutral line was. However, the closure of the slow expansion fans carrying solar wind plasma into the tail lobes was a natural way to force tail reconnection (Coroniti and Kennel, 1979). This closure point is fifty to one hundred earth radii downstream of earth. Twenty-four years were to pass before the average location of the tail neutral line could be established, because no spacecraft until ISEE-3 spent enough time that far downtail. In retrospect, it is a testament to the power of the paradigm that so many would search for so long for direct evidence of dayside and nightside reconnection without jettisoning Dungey’s model altogether. Faith in Dungey’s model was sustained by its collateral predictions. The access of energetic particles of solar origin to the polar cap ionosphere confirmed that reconnection occurs.
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Epstein, Irving R., and John A. Pojman. "Stirring and Mixing Effects." In An Introduction to Nonlinear Chemical Dynamics. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195096705.003.0021.
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In almost everything that we have discussed so far, we have assumed, explicitly or implicitly, either that the systems we are looking at are perfectly mixed or that they are not mixed at all. In the former case, concentrations are the same everywhere in the system, so that ordinary differential equations for the evolution of the concentrations in time provide an appropriate description for the system. There are no spatial variables; in terms of geometry, the system is effectively zero-dimensional. At the other extreme, we have unstirred systems. Here, concentrations can vary throughout the system, position is a key independent variable, and diffusion plays an essential role, leading to the development of waves and patterns. Geometrically, the system is three-dimensional, though for mathematical convenience, or because one length is very different from the other two, we may be able to approximate it as one- or two-dimensional. In reality, we hardly ever find either extreme—that of perfect mixing or that of pure, unmixed diffusion. In the laboratory, where experiments in beakers or CSTRs are typically stirred at hundreds of revolutions per minute, we shall see that there is overwhelming evidence that, even if efforts are made to improve the mixing efficiency, significant concentration gradients arise and persist. Increasing the stirring rate helps somewhat, but beyond about 2000 rpm, cavitation (the formation of stirring-induced bubbles in the solution) begins to set in. Even close to this limit, mixing is not perfect. In unstirred aqueous systems, as we have seen in Chapter 9, it is difficult to avoid convective mixing. Preventing small amounts of mechanically induced mixing requires considerable effort in isolating the system from external vibrations, even those caused by the occasional truck making a delivery to the laboratory stockroom. It is possible to suppress the effects of convection and mechanical motion in highly viscous media, such as the gels used in the experiments on Turing patterns as discussed in the previous chapter. There, we can finally study a pure reaction-diffusion system. Systems in nature—the oceans, the atmosphere, a living cell—are important examples in which chemical reactions with nonlinear kinetics occur under conditions of imperfect mixing.
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"Fig. 14 Scraped-surface anchor agitator with auxiliary crossbar agitator. (From Ref. 20.) have many deleterious effects on it. First, the emulsion may have components that cannot stand the wall temperature, which may be as high as 110-125°C. This is even more important if the dosage has active ingredients that decompose at these temperatures. Second, if the temperature is hot enough, the product may actually stick or burn on the sidewall. Cooling of product through sidewall heat transfer can cause almost as many prob-lems as heating. During cooling, the viscosity of a product almost always increases. A viscous product that is not physically removed from the sidewall builds up and forms an insulating layer than resists efficient heat transfer. Again, once this condition oc-curs, it is very difficult to reverse it. There is a variety of different designs of scraper blades. Some are arranged in rows. Some are offset on either side of the anchor, allowing some overlap as an an-chor makes a complete revolution. Some actually are designed to allow the anchor to revolve in opposite directions, which can prevent the buildup of product on the fol-lowing edge of the anchor. Some designs use a spring to force the blade against the wall. Most modern designs use the force of the liquid flowing into the blade to bring it close to the wall. Scraped-surface agitators are definitely required in emulsification equipment where heat transfers are necessary. These anchor agitators with scraping blades can be just as simple anchors or part of complex multishaft mixers. 5. Counterrotation Anchor-type agitators have a decided weakness when handling high-viscosity products of more than about 75,000-100,000 centipoise. They tend to rotate only the product,." In Pharmaceutical Dosage Forms. CRC Press, 1998. http://dx.doi.org/10.1201/9781420000955-41.
Full textConference papers on the topic "The cloven viscount"
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Shu, Jian-Jun. "Two-Dimensional Unsteady Viscous Flows." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62465.
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A number of new closed-form fundamental solutions for the two-dimensional generalized unsteady Oseen and Stokes flows associated with arbitrary time-dependent translational and rotational motions have been developed. As an example of application, the hydrodynamic force acting on a circular cylinder translating in an unsteady flow field at low Reynolds numbers is calculated using the new generalized fundamental solutions.
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Burmasheva, N. V., E. A. Larina, and E. Yu Prosviryakov. "Unidirectional convective flows of a viscous incompressible fluid with slippage in a closed layer." In MECHANICS, RESOURCE AND DIAGNOSTICS OF MATERIALS AND STRUCTURES (MRDMS-2019): Proceedings of the 13th International Conference on Mechanics, Resource and Diagnostics of Materials and Structures. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5135147.
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Liu, Li-qin, Jin-shuang Man, and Yu Qiu. "The Added Mass and Viscous Damping of a Spar Platform With Semi-Closed Moon Pool." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41067.
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The CFD (Computational Fluent Dynamics) method was used to calculate the added mass and the viscous damping of the Spar platform considering the semi-closed moon pool in this paper. The three-dimensional models of the platform with water inside the semi-closed moon pool were established by the VOF (Volume of Fluid) method. The UDF (User Defined Function) was adopted to oscillate the platform. The added mass and the damping coefficients were calculated under different KC (Keulegan-Carpenter) number and flow velocity for different opening ratio of the moon pool. The viscous damping and natural period of the platform heaving were obtained by calculating the platform motion in the static water. The influences of water inside the moon pool on the Spar platform motion were analyzed.
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S¸eker, Deniz, and Nilufer Eg˘rican. "Turbulent Heat and Mass Transfer Inside Open and Closed Cavities." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42820.
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Natural convection inside open and closed cavities provides a suitable benchmarking problem for viscous flow calculations. The necessity of solving the energy equation coupled with momentum equations, the difficulty to determine the boundary conditions on the cavity walls and absence of an appropriate turbulence model for that type of flows remain the problem unsolved.
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Xu, L. "Assessing Viscous Body Forces for Unsteady Calculations." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30359.
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A strategy has been developed to model the three dimensional unsteady flows through turbomachines subject to non-axisymmetric flow/geometrical conditions such as low order distortions with relatively long length scale unsteadiness, by modelling the viscous effects as local source terms for a coarse computational mesh but not calculating them directly. In general full annulus multirow calculations are required for such flows but currently the computational resources are devoted to resolving detailed viscous flow very close to the walls, which in some cases is not the centre of concern. By avoiding resolving detailed viscous effects the model can accelerate the calculation by at least two orders of magnitude. The method has been illustrated to be able to resolve disturbances down to the blade passing frequency and give good estimates of overall unsteady blade forces due to blade row interactions. Obviously the correct modelling of the viscous body force as source terms in the governing equations is the key for accuracy of such calculations. Different ways of constructing/approximating the viscous body force term are discussed and their adequacy in unsteady flow calculations is assessed. It is found that in general the viscous force is relatively small compared to the total blade force, even smaller the unsteady fluctuation of the viscous force and a simple drag coefficient model is quite adequate to model both time mean and dynamic viscous effects. Whilst for the cases when separations are present variations in the drag coefficient may become large and more detailed modelling may be required.
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Holmes, Samuel, Joseph Gebara, and Allan Magee. "Centerwell Water Motions and Hydrodynamic Loading Using Viscous Flow Calculations." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57882.
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Most Spar platforms have a wet centerwell which provides a termination point for umbilicals and risers. The column of water in the centerwell is a dynamic system which can be excited by the wave action around the Spar as well as the platform’s own motions. When the exciting frequencies are close to the natural frequency of the water column, the vertical motion of the water in the centerwell can become large in large seastates. This might damage structures within the centerwell. A natural response to this problem is to restrict the fluid flow at the bottom of the centerwell by adding a plated structure to partially close the opening. The remaining open area in the centerwell determines the amount of damping as well as the loads on the plating which can be quite large in heavy seas. The problem addressed in this paper is the determination of the appropriate open area in the centerwell plate that will control the fluid vertical motion without requiring expensive reinforcements to the plating beyond the riser guide structure already present. Traditional design tools based on potential flow models appear to perform poorly for this problem because they do not model the viscous damping in the flow correctly. In this paper we use a Navier-Stokes solver to study the centerwell motions and centerwell plate loads for three centerwell plate geometries. It is found that the Spar motions and the free surface waves need to be included in these simulations. The centerwell water motions and centerwell plate loads are compared with those measured in a scale model experiment. Full-scale calculations are also carried out to determine the corresponding centerwell plate loads and centerwell water motions to assess scale effects.
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Bouscasse, Benjamin, Andrea Colagrossi, Salvatore Marrone, and Antonio Souto-Iglesias. "High Froude Number Viscous Flow Past a Circular Cylinder." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41857.
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Two-dimensional monophasic flow past a circular cylinder intersecting or close to a free surface at Reynolds 180 is numerically investigated using the Smoothed Particle Hydrodynamics (SPH) method. The wake behaviour for a range of conditions with Froude numbers between 0.3 and 2.0, a gap ratio of 0.55 and for a half-submerged cylinder are studied. The SPH technique allows for a non-diffusive computation of the free surface evolution, even while breaking and fragmentation may occur. Vorticity shed by the cylinder, vortex generation due to free surface breaking, mixing processes, and drag and lift coefficients behaviour are discussed. It has been found that, for certain Froude numbers and for the analysed submergence ratio, a vorticity layer remains spatially localized between the cylinder and the free surface and a large recirculating wake area develops, which eventually gets detached after several shedding cycles, being advected downstream, a previously unreported form of wake instability, to the authors’ knowledge. This behaviour is blocked when the cylinder is intersecting the free surface.
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Burmasheva, N. V., E. A. Larina, and E. Yu Prosviryakov. "Unidirectional convective flow of viscous incompressible fluid in a closed horizontal layer with the perfect slip condition." In MECHANICS, RESOURCE AND DIAGNOSTICS OF MATERIALS AND STRUCTURES (MRDMS-2020): Proceeding of the 14th International Conference on Mechanics, Resource and Diagnostics of Materials and Structures. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0036714.
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Haller, Brian. "Development of New High AN2 Last LP Stage Turbine and Exhaust Systems: A Cost Effective Solution for the 21st Century." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90009.
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A new high AN2 last LP stage turbine has been developed to provide leading performance for turbomachines in the 21st Century. It required a multi-disciplinary design approach involving aerodynamics, materials, mechanics (stress and vibration) and manufacturing technologies. The objective of the design was to achieve around 5% gain in last stage total-to-static efficiency, relative to the current competitive datum, for a very compact machine with few parts count ie reduced cost. It is shown how the optimum aerodynamic design was achieved for the stage. The paper presents details of the novel approaches used for the design including preliminary optimization, blading design and results from multistage 3D viscous predictions. The new stage has been tested in a Warm Air Turbine test rig at full scale engine representative conditions. The “loop was closed” by comparing the detailed test measurements with throughflow and 3D viscous analyses. This gives high confidence in the new approaches used. Additionally, the development of new compact high performance axial-radial and axial exhaust systems, which were designed to operate downstream of the new last LP stage, are described. To achieve the optimum performance, the last LP stage has to designed as a coupled system with the exhaust diffusers. The new LP technologies have already been scaled and cloned to a new engine design and sold by the Company.
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Bahrainian, Seyed Saied, and Zahra Mehrdoost. "A Novel Hybrid Approach for Unstructured Viscous Grid Generation." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24325.
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Accurate solution of boundary layer and wake flow require generation of high aspect ratio grids in these regions. A hybrid approach for the efficient generation of inviscid and viscous unstructured grids has been introduced. A novel feature of the current work is its ability to produce boundary layer and wake grids that enables accurate flow solutions in viscous flow regions. The grid generation algorithm starts with a very coarse initial grid. In the inviscid region, isotropic cells of excellent quality are produced using a combination of point insertion and cell subdivision techniques. Simultaneously, a directional grid refinement strategy is used to construct highly stretched triangular cells in viscous regions. First, anisotropic unstructured grids are produced in the stream wise direction. Then, cells close to the solid surface are refined to highly stretched layer of triangles suitable for boundary layer region. Smooth transition between the boundary layer grid and the outer isotropic grid is easily obtained with a user specified cell size and stretch. The accuracy of the current grid generation approach is assessed by laminar and turbulent compressible flow solutions around NACA0012 and RAE2822 airfoils. The results of the numerical flow simulations are compared with published experimental and numerical data. Comparisons point to the ability of the proposed unstructured boundary layer and wake grid generation procedure.