Forced Volume Research Articles

Numerical and experimental study of field synergy analysis in water jet impingement based on minimum entropy generation method

Most detailed reviews of field synergy principle FSP are mainly focused on numerical approaches, while validating first deduction of FSP experimentally is very rare. Therefore, an experimental analysis is carried out on a simple heated plate surface. Experiments are conducted using infrared thermal-vision system and a professional high-speed camera. The field study concerns the hydrodynamic and water jet velocity ratio based on four different configurations under relatively low jet Reynolds number ranging from 2602 to 6505 and to be optimized by FSP. New analytical equations are developed to verify experimentally the synergy between velocity streamline and temperature field as well as synergy number especially in the mid integral areas where images have clear appearance along the lateral direction of the heated plate. Laminar heat flow field synergy equation is developed based on the minimum entropy generation MEG method, and it is treated for relatively low Reynolds number in order to reduce computational effort and time cost. The new proposed laminar heat synergy optimization equation is deduced by setting irreversibility of heat transfer process under the additional assumption that constraint of thermal generation by mechanism of viscous dissipation is considered. The variation principles with respect to velocity give new Navier–Stokes equation with additional volume force, which is constructed through functional variation of Lagrange multipliers to numerically simulate convective heat transfer. Solving simultaneously the field synergy equations (Fx​, Fy​, Fz) for input constant related to viscous dissipation equal to −1.0E05 will give several synergy flow fields which are followed by gradual increase of entropy generation rate as ratio of H/D increases.

The linear response of turbulent flow to a volume force: comparison between eddy-viscosity model and DNS

We identify a benchmark problem simple enough that it can be solved both by an eddy-viscosity model and by direct numerical simulation: this is the linear response of a turbulent flow’s mean-velocity profile to an external volume force. An example of such a force was found in a study of the perturbation induced by bottom topography by Luchini & Charru (J. Fluid Mech., vol. 656, 2010, pp. 337–341). On the other hand, a modification of the method by Quadrio & Luchini (Proceedings of the IX European Turbulence Conference, Southampton, UK, 2002, pp. 715–718) and Luchiniet al. (Phys. Fluids, vol. 18, 2006, 121702) to compute the linear impulse response of a wall-bounded turbulent flow allows the response to a volume force to be computed directly. The comparison exhibits significant differences and suggests that there might be fundamental obstacles to designing an eddy-viscosity model that provides the correct result.

Économie et finances publiques des cités grecques, vol. 2 : Choix d'articles publiés de 2002 à 2014 by Léopold Migeotte

196 PHOENIX an argument for the continuing relevance of the Athenian conception of courage. By presupposing a less sharp distinction between individual and community, and emphasizing the importance of deliberation, Athenian democratic courage can inform contemporary discussions about the scope of courage and its connection to violence and justice in modern democracies. As is evident from the summary of this rather long book, Balot has mastered an impressive amount and range of primary sources, including historiography, oratory, tragedy, comedy, and philosophy, and provides an all-encompassing account of the ideology of democratic courage. The author does a masterful job in contextualizing Athenian courage, but his study goes beyond being a narrow analysis of the workings of a particular virtue in its cultural context. On the one hand, without ever losing focus on his central theme, Balot offers critical insights into wider aspects of Greek ethical thinking, such as the nature of human flourishing (eudaimonia) and the importance of shame as a motivating factor. On the other hand, by drawing on modern political theory, Balot highlights the universal significance of courage as a virtue and suggests ways in which Athenian courage may become relevant to modern political debates. The author offers novel and stimulating readings of well-known texts (the discussions of Plato’s Laches and Aristophanes ’ Lysistrata through the lens of democratic courage are two prominent examples), and though not all of his conclusions will satisfy all scholars (Balot’s insistence on the superiority of democratic courage as opposed to other forms may be a case in point), this is to be expected for a work on such a complex and contested topic. A major contribution of the book is the explicit link it draws between democratic ideology and the concept of eudaimonia, which was later to become a focal point in Plato and Aristotle, stressing thus the influence that Athenian democratic discourse had on the work of the philosophers, despite their critical stance towards democracy itself (that said, I would have expected a separate discussion of Aristotle’s account of courage in Balot’s book, although, of course, the author does often refer to the discussion of andreia in the Nicomachean Ethics). The writing is admirably clear throughout, the level of analysis is consistently high, and the meticulous and thoughtful analysis of the ancient sources is informed by a wealth of scholarly literature on a number of topics ranging from Greek ethics and social history to modern political theory and theories of emotion. Balot’s book is an important contribution that deepens our understanding of the workings of courage in democratic Athens and will therefore be of value to students and scholars in the fields of classics and ancient history, philosophy, and political theory. University of St Andrews Kleanthis Mantzouranis  Economie et finances publiques des cit es grecques, vol. 2 : Choix d'articles publi es de 2002 Á a 2014. Par L eopold Migeotte. Lyon : Maison de l’Orient et de la Méditerranée–Jean Pouilloux, Collection de la Maison de l’Orient 54. Pp. 466. Ce volume 2, qui rassemble un choix d’articles de Léopold Migeotte publiés de 2002 à 2014, fait suite au volume 1 (Lyon, 2010), qui rassemblait les articles du même savant publiés de 1976 à 2001. Aux trente-cinq articles du premier volume succèdent les trentedeux du second. Après L’emprunt public dans les cités grecques : recueil des documents et analyse critique (Québec et Paris, 1976) et Les souscriptions publiques dans les cités grecques (Genève BOOK REVIEWS/COMPTES RENDUS 197 et Québec, 1992), Léopold Migeotte a récemment publié son opus magnum, Les finances des cités grecques aux périodes classique et hellénistique (Paris, 2014). Au fil des années, pour mieux asseoir les raisonnements de ses divers ouvrages et pour s’éviter des démonstrations détaillées qui n’y auraient pas trouvé place, l’auteur a publié une impressionnante série d’articles et de comptes rendus dont la plupart se retrouvent dans les deux volumes de choix d’articles. Les études sont regroupées en six chapitres : « Gestion financière » (onze articles) ;« Taxation...

Numerical Simulation of Chip Ploughing Volume and Forces in 5-axis CNC Micro-milling Using Flat-end Mills

It is a challenging task to avoid ploughing effects in micro-milling. When one tooth of the cutting tool crosses the minimum chip thickness boundary, the tool would enter into the ploughing zone with no chip formation. Therefore, it is significant to predict the ploughing volume and forces in micro-milling. In this work, the ploughing mechanism for micro-milling is proposed by considering the minimum chip thickness effects. A 3D chip geometry is developed to calculate chip thickness, ploughing volume and ploughing forces in micro 5-axis flat-end milling with a flat-end mill. The local parallel sliced tool based method is then applied to get cutter-workpiece engagement domain where the cutting flutes entry and exit the workpiece, minimum chip thickness and depth of cut are required to predict ploughing forces. Local parallel sliced method divides the cutting tool into several slices that are perpendicular to the tool axis along the local coordinate system. On each layer, the removal chip area is dividing into ploughing zone and shearing zone by the minimum chip thickness. Ploughing zone is the area as chip thickness is less than the minimum chip thickness. In the shearing zone, chip thickness is larger than the minimum chip thickness. The total chip ploughing volume is obtained by adding all ploughing area along axial direction.

Modeling of weighing and filtration forces in the “dam-foundation” system

The authors carried out the modeling of weighing and filtration forces in the “dam-foundation” system through the methodology of modeling of piecewise-potential volume forces based on the equivalence of effects. They considered a uniform “dam-foundation” system with a drainage structure. The depression curve is taken as a broken line, therefore the filtration flow causes the influence of weighing and filtration forces on the part of this system. The modeling of the effect of filtration forces (which are potential ones) is performed by the method of the equivalence of effects. The experimental studies showed that the effects of the filtration flow at the level of the drainage structure were considerably weaker than those at the level of the foot of the dam. The effects by both the weighing forces and the filtration ones with the given domain configuration considerably reduce the compressive stresses in the foot of the dam at its upstream face caused by the effect of the dam mass, which makes worse the static work of the dam.

Jean-Jacques Rousseau et l’exigence d’authenticité: une question pour notre temps par Jean-François Perrin, Yves Citton

reste passionnante à condition que le lecteur fasse preuve de détermination. L’épilogue, bref et peu concluant, risque pourtant de le laisser perplexe. Bard College (NY) Éric Trudel Perrin, Jean-François, et Yves Citton, éd. Jean-Jacques Rousseau et l’exigence d’authenticité: une question pour notre temps. Paris: Garnier, 2014. ISBN 978-28124 -3080-0. Pp. 474. 49 a. Perrin and Citton have compiled twenty-two papers presented at a 2012 conference at Université Stendhal, Grenoble commemorating the tricentennial of Rousseau’s birth. This book’s theme treats the notion of authenticité as presented in the writings of Rousseau, of his contemporaries, and of those he influenced. It also attempts to show how Rousseau’s concept of authenticity continues to provoke thought and discussion. The selections are organized under four headings. The first section, “Confrontations,” places Rousseau’s definition of the term on a historical continuum of philosophical debate, which encompasses the ideas of both ancient and modern thinkers. Under “Tensions,” the title of the second grouping, contributors examine reactions to the theoretical, ethical, and existential contradictions prompted by authenticité and revealed in Rousseau’s works, thinking, and life. The third section focuses on the writings themselves. It is appropriately entitled “Compositions” and again targets Rousseau’s contradictions, this time, however, those penned by the author himself in various works.In the introduction,Perrin notes that if there is an authenticité in Rousseau, it can be read in the thinker’s own inconsistencies. The concluding portion “Évolutions” speaks to early influences on Rousseau’s ethic of truth and sincerity as well as his impact on literary works of the eighteenth century and beyond. Many of the most engaging essays are found in the second and third sections. For example, Antoine Lilti and John C. O’Neal tie in their reflections on authenticité to the current concepts of celebrity and media, making Rousseau and his idea of authenticity relevant to our era. Lilti underscores the obstacles that Rousseau faced as a public figure. In modern terminology, he was a star. As a victim of his own fame, he had to contend with critics who exposed contradictions between his words and actions. Consequently, he was forced to reaffirm his own sincerity in light of the public’s perception.As is the case with many of today’s public figures, Rousseau’s moral integrity, his“authenticité morale”(201) was threatened. The editors fittingly selected a related article on media and public opinion to follow. In his study, O’Neal hypothesizes Rousseau’s reaction to Facebook. Given his belief that happiness can be found only in our true or authentic selves, not in the opinion of others, Rousseau would be skeptical of the good of this cultural phenomenon. To him, it would signify an instrument of dehumanization and alienation. To Facebook’s millions of adherents, 276 FRENCH REVIEW 90.2 Reviews 277 loss of liberty matters little compared to the allure of unlimited friends and exposure that it offers. Independent Scholar Ivy Dyckman Romestaing, Alain, et Alain Schaffner, éd. Animaux d’écritures: le lien et l’abîme. Paris: Garnier, 2014. ISBN 978-2-81243-364-1. Pp. 198. 46 a. D’une grande diversité d’approches et d’objets, les contributions à ce volume ont pour préoccupation commune ce qui dans la question animale peut intensifier ou mener à ses limites la raison romanesque. Si l’enquête de ce numéro hors-série de la revue Romanesques ne se limite pas au roman (voir les belles pages d’Élisabeth Plas consacrées à Michelet naturaliste), elle envisage bien l’animal, par une attention soutenue à des questions de forme et aux possibles narratifs, en tant que problème d’écriture, et inquiétude du savoir littéraire. Les tropes, écrit Lucile Desblache au détour d’une discussion ambitieuse de l’allégorie chez Chamoiseau, sont des “instruments de prise de conscience du monde vivant”(109).Aussi certains essais du recueil, consacrés aux œuvres de Zola (Jean-Louis Cabanès), Louis Pergaud (Alain Schaffner), Maurice Genevoix (Nicolas Picard), dégagent dans les textes les voies précises d’une empathie possible, et qui incombe, face à la souffrance animale. Zola devance l...

Sapphic Fathers: Discourses of Same-Sex Desire from Nineteenth-Century France by Gretchen Schultz

Reviews 207 conservées à la bibliothèque municipale de Lyon, rédigée et copieusement annotée par Sophie Astier. Les éditeurs de ce volume ont voulu faire revivre la figure d’un polygraphe dont les seiziémistes rencontrent souvent le nom dans les textes publiés entre 1540 et 1550. Ils y sont remarquablement parvenus en offrant de stimulantes pistes de recherche pour ceux qui s’intéressent non seulement à la poésie de la Renaissance, mais plus généralement à l’histoire de la littérature, de la culture et de la poétique. University of Maryland, College Park Hervé-Thomas Campangne Schultz, Gretchen. Sapphic Fathers: Discourses of Same-Sex Desire from NineteenthCentury France. Toronto: UP of Toronto, 2015. ISBN 978-1-4426-4672-8. Pp. xix + 295. $65. From 1850 to 1900, France witnessed an explosion of lesbian-themed literature. A discourse produced chiefly by men (the“Fathers”of the title), the poetry and fiction about lesbians informed the nascent disciplines of sexology and psychology, and were, in their turn, influenced by the findings of the positivist scientific community. With the goal of exploring how representations of lesbianism become available to a sexual minority lacking an awareness of itself, Schultz begins her erudite and nuanced analysis with Baudelaire’s and Verlaine’s sapphic poetry in which she locates possibilities for sapphic investment as subjects of discourse. It is a unique moment of opportunity. All subsequent representations, at least until century’s end, treat the lesbian solely as object of discourse. Chapter two,“Tribades for Sale,”examines Adolphe Belot’s prolific lesbian-themed oeuvre within the context of the period’s expanding readership and publishing industry. Schultz moves deftly through Belot’s novelistic production as she traces the formation of clichés and stereotypes, and the hardening of the contours and conventions governing various genres. The next two chapters focus on Péladan’s The Gynander (1891) and Mendès’s Méphistophéla (1890) on the one hand, and the evolving scientific discourse on sexual“pathologies,”hysteria, prostitution , and heredity in France on the other. The latter analysis demonstrates the centrality of the figure of the lesbian to cultural anxieties about depopulation, loss of national prestige, democratization, and shifting gender roles. The subtle readings of the first four chapters culminate in “Intertexts and Afterlives,” in which the reader is afforded a romp through lesbian pulp fiction in the United States between the 1930s and the 1960s, and the role this flourishing industry might have played in lesbian identity formation. One of the amazing “take-aways” of this ambitious study is the uncovering of the enormous intertextual debt of the American lesbian pulp movement to the French “sapphic fathers.” Schultz has given us an elegant and sweeping survey of the discourses that converged and overlapped to produce representations of the lesbian in France in the last half of the nineteenth century. She has convincingly linked these representations to the shifting ideologies and political valences of the day. One of the beauties of her analysis of representations of lesbianism lies in the fact that Schultz consistently chooses ambiguity and ambivalence over easy categorization. She problematizes the moralizing stance of Belot’s popular novels by invoking his other, shadier pornographic oeuvre, which is more ambivalent about Lesbos. She shows Mendès’s work to be marked by similar ambiguities. Schultz’s willingness and ability to hold contradictions in suspension serve her well as she concludes that, in the absence of a consolidated sapphic community, and given a representational void, this French male-authored body of fiction, however much it objectified and occasionally vilified sapphist practices, nonetheless provided a site of self-recognition and identification . At the very least, the French sapphist fathers were a starting point for lesbian identity formation in the United States even if their representations would be challenged and transcended as the homophile movement gained traction over time. University of Maryland, College Park Carol Mossman Solomon, Nathalie. Voyages et fantasmes de voyages à l’époque romantique. Toulouse: PU du Mirail, 2014. ISBN 978-2-8107-0291-6. Pp. 307. 24 a. On s’étonnerait presque qu’un territoire aussi largement exploré que la littérature des voyages puisse...

Interfacial and mechanical properties of epoxy composites containing carbon nanotubes grafted with alkyl chains of different length

Dispersion of the nano-fillers is important in the manufacture of high performance nanocomposites. Dispersion of silane treated CNT/epoxy composites was analyzed for various alkyl chain lengths. Difference in mobility of alkyl chains of different length affects the excluded free volume and repulsive forces. An optimal chain length was observed to impart maximum mechanical and impact properties. Differences in the dispersion of CNT due to alterations in alkyl chain lengths were determined using electrical resistance measurement. Spreading of CNT/epoxy rearranged the CF tow resulting in a change in electrical resistance ratio (CERR) and the differences in alkyl chain length effected CNT spreading. Dispersion and wetting conditions with different alkyl chain lengths resulted in changes in CERR, ILSS and other proprieties. The butyl chain length was optimal of the alkyl chain lengths studied. This is attributed to the butyl chains known good mobility and steric repulsion effects compared to longer alkyl chain lengths.

Finite-Element Formulation of a Nonlocal Hereditary Fractional-Order Timoshenko Beam

AbstractA mechanically-based nonlocal Timoshenko beam model, recently proposed by the authors, hinges on the assumption that nonlocal effects can be modeled as elastic long-range volume forces and moments mutually exerted by nonadjacent beam segments, which contribute to the equilibrium of any beam segment along with the classical local stress resultants. Long-range volume forces/moments linearly depend on the product of the volumes of the interacting beam segments, and on pure deformation modes of the beam, through attenuation functions governing the space decay of nonlocal effects. This paper investigates the response of this nonlocal beam model when viscoelastic long-range interactions are included, modeled by Caputo’s fractional derivatives. The finite-element method is used to discretize the pertinent fractional-order equations of motion. Closed-form solutions are obtained for creep tests by typical tools of fractional calculus. Numerical results are presented for various nonlocal parameters.

Numerical Solution to a One-Dimensional, Nonlinear Problem of Thermoelasticity with Volume Force and Heat Supply in a Slab

A numerical solution is presented for a one-dimensional, nonlinear boundary-value problem of thermoelasticity with variable volume force and heat supply in a slab. One surface of the body is subjected to a given periodic displacement and Robin thermal condition, while the other is kept fixed and at zero temperature. Other conditions may be equally treated as well. The volume force and bulk heating simulate the effect of a beam of hot particles infiltrating the medium. The present study is a continuation of previous work by the same authors for the half-space [1]. The presented Figures display the process of propagation and reflection of the coupled nonlinear thermoelastic waves in the slab. They also show the effects of volume force and heat supply on the distributions of the mechanical displacements and temperature inside the medium. The propagation of beats provides evidence for sufficiently large time values.

Unsteady axisymmetric deformation of an elastic thick-walled sphere under the action of volume forces

This paper considers a homogeneous isotropic elastic body bounded by concentric spheres and acted upon by axisymmetric unsteady volume forces. Displacement fields are determined using series expansions in Legendre and Gegenbauer polynomials, Laplace transforms in time, and integral representations with kernels in the form of Green’s functions. Explicit formulas for the Green’s functions are constructed that allow accurate determination of the originals. Examples of the calculations are presented.

A path-conservative finite volume scheme for compressible multi-phase flows with surface tension

The accurate simulation of compressible multi-phase flows with surface tension effects is currently still one of the most challenging problems in computational fluid dynamics (CFD). The basic difficulties are the capturing of the correct interface dynamics between the two fluids as well as the computation of the interface curvature. In this paper, we present a novel path-conservative finite volume discretization of the continuum surface force method (CSF) of Brackbill et al. to account for the surface tension effect due to curvature of the phase interface. This is achieved in the context of a diffuse interface approach, based on the seven equation Baer–Nunziato model of compressible multi-phase flows. Such diffuse interface methods for compressible multi-phase flows including capillary effects have first been proposed by Perigaud and Saurel. In the CSF method, the surface tension effect is replaced by a volume force, which is usually integrated as a classical volume source term. However, since this source term contains the gradient of a color function that is convected with the flow velocity, we propose to integrate the CSF source term as a non-conservative product and not simply as a source term, following the ideas on path-conservative finite volume schemes put forward by Castro and Parés.For that purpose, we use the new generalized Osher-type Riemann solver (DOT), recently proposed by Dumbser and Toro and compare it with a path-conservative Roe and Rusanov scheme. Via numerical evidence we can show that if the curvature computation is exact, our new scheme is well-balanced for a steady circular bubble in equilibrium according to the Young–Laplace law. This means that the pressure jump term across the interface in the momentum equation is exactly balanced with the surface tension force.We apply our scheme to several one- and two-dimensional test problems, including 1D Riemann problems, an oscillating droplet, as well as a deforming droplet initially attached to a wall and which is subject to gravity and surface tension forces. Finally, we also check the rising of a gas bubble due to buoyancy forces. We compare our numerical results with those published previously in the literature.

Sliding droplets of Xanthan solutions: A joint experimental and numerical study.

We have investigated the sliding of droplets made of solutions of Xanthan, a stiff rodlike polysaccharide exhibiting a non-Newtonian behavior, notably characterized by a shear thinning viscosity accompanied by the emergence of normal stress difference as the polymer concentration is increased. These experimental results are quantitatively compared with those of Newtonian fluids (water). The impact of the non-Newtonian behavior on the sliding process was shown through the relation between the average dimensionless velocity (i.e. the capillary number) and the dimensionless volume forces (i.e. the Bond number). To this aim, it is needed to define operative strategies to compute the capillary number for the shear thinning fluids and compare with the corresponding Newtonian case. The resulting capillary number for the Xanthan solutions scales linearly with the Bond number at small inclinations, as well known for Newtonian fluids, while it shows a plateau as the Bond number is increased. Experimental data were complemented with lattice Boltzmann numerical simulations of sliding droplets, aimed to disentangle the specific contribution of shear thinning and elastic effects on the sliding behavior. In particular the deviation from the linear (Newtonian) trend is more likely attributed to the emergence of normal stresses inside the non-Newtonian droplet.

Steady state in a gas of inelastic rough spheres heated by a uniform stochastic force

We study here the steady state attained in a granular gas of inelastic rough spheres that is subject to a spatially uniform random volume force. The stochastic force has the form of the so-called white noise and acts by adding impulse to the particle translational velocities. We work out an analytical solution of the corresponding velocity distribution function from a Sonine polynomial expansion that displays energy non-equipartition between the translational and rotational modes, translational and rotational kurtoses, and translational-rotational velocity correlations. By comparison with a numerical solution of the Boltzmann kinetic equation (by means of the direct simulation Monte Carlo method), we show that our analytical solution provides a good description that is quantitatively very accurate in certain ranges of inelasticity and roughness. We also find three important features that make the forced granular gas steady state very different from the homogeneous cooling state (attained by an unforced granular gas). First, the marginal velocity distributions are always close to a Maxwellian. Second, there is a continuous transition to the purely smooth limit (where the effects of particle rotations are ignored). And third, the angular translational-rotational velocity correlations show a preference for a quasiperpendicular mutual orientation (which is called “lifted-tennis-ball” behavior).

The influence of plasma actuators material and geometry on the electromagnetic characteristics of the discharge and the specific thrust of synthetic jets

It was examined the effect of electrode material on the value of specific thrust of the synthetic jets produced by symmetric actuator. The dependences of specific thrust on the distance between external electrodes for copper, aluminium, nickel and titanium was made. A considerable effect of the shape of the external electrodes on the electric field and current density in the tape drive and the specific thrust of the synthetic jet were investigated. The role of autoelectronic emission on the current in streamers and the value of volume force acting on the stream were also evaluated.

Математическая модель нестационарного термоупругого деформирования многослойных демпфирующих покрытий в радиоэлектронной аппаратуре

Generation of new multilayer coatings of units and blocks in electronics for effective damping of thermo-mechanical impact loads requires the development of mathematical models suitable for engineering practice. Mathematical model and calculation method proposed in this paper allows investigate the passing and reflection of thermo-elastic waves in a multilayer body excited by non-stationary magnetic field at the conductive layer boundary. Also, the problem of estimating relative influence of volume forces induced by the magnetic field in the electrically conductive nonferromagnetic layer on the wave propagation in thermo-elastic polymer compounds was considered. It is assumed that the velocity of heat propagation is finite. Assumptions are introduced to simplify the fully coupled system of magneto-thermo-elastic equations that allow applying the numerical solution based on the method of characteristics for obtaining concrete results. A method for finding required quantities at the nodal points of the boundary between the layers is indicated. The suggested mathematical model and calculation method makes it possible, without making any significant changes in the computing system, to carry out numerical experiments on researching the damping properties of multilayer coatings with different geometrical and mechanical parameters under the conditions of the thermo-mechanical loadings. This calculation method of heterogeneous multilayer thermo-elastic structures can be used to identify the areas most disposed to the damage.

Free Boundary Problem of Magnetohydrodynamics

A free boundary problem controlling the motion of a finite isolated mass of a viscous incompressible electrically conducting fluid in vacuum is considered. The fluid is moving under the action of a magnetic field and volume forces. It is proved that this free boundary problem is solvable in an infinite time interval under additional smallness assumptions imposed on the initial data and the external forces.

Charging method of micro heat pipe for high‐power light‐emitting diode

Since high precision of working fluid charging is key to the evaluation of thermal performance, a novel perfusion method of a micro heat pipe (MHP) is presented. The MHP has a length of 26 mm, width of 20 mm and a thickness of ∼2.2 mm. The predetermined quantity of perfusion is 25 or 35 μl. Small volume and large capillary force render conventional vacuum perfusion methods quite impractical. To realise microscale and high precision of perfusion, the method of combining vacuum perfusion using a peristaltic pump and weight comparison before and after working fluid charging was used. The charging deviation of the method was <2 μl. After perfusion and sealing, the thermal performance testing of a MHP, which is engineered in light-emitting diode (LED) heat dissipation, was conducted and the input power varied from 1 to 7 W. The results show that high-power LEDs can reach the status of heat balance and can work steadily, and the maximum deviations of actual and simulated temperatures are 4.5 and 5.1°C, respectively, and the relative errors are 6.1 and 7.3%. Therefore, this perfusion method can be used for the working fluid perfusion of the MHP and makes it feasible for use in packaging manufacture of heat pipes.

Matrix-free Brownian dynamics simulation technique for semidilute polymeric solutions.

Evaluating the concentration dependence of static and dynamic properties of macromolecules in semidilute polymer solutions requires accurate calculation of long-range hydrodynamic interactions (HI) and short range excluded volume (EV) forces. In conventional Brownian dynamics simulations (BDS), computation of HI necessitates construction of a dense diffusion tensor commonly performed via Ewald summation. Krylov subspace techniques allow efficient decomposition of this tensor [computational cost scales as O(N^{2}), where N is the total number of beads in bead-spring representation of macromolecules in a simulation box] and computation of Brownian displacements in the box. In this paper, a matrix-free approach for calculation of HI is implemented which leads to O(NlogN) scaling of computational expense. The fidelity of the algorithm is demonstrated by evaluating the asymptotic value of center-of-mass diffusivity of polymer molecules at very low concentrations and their radius of gyration scaling as a function of number of beads for dilute and semidilute solutions (with concentrations up to 5 times the overlap concentration). In turn, a favorable comparison between our results and the blob theory is shown.

Evaluation of the time-resolved EHD force produced by a plasma actuator by particle image velocimetry - a parametric study

Surface plasma discharges, and more specifically dielectric barrier discharge, find several applications in aerodynamic due to their capability to produce a local flow at the dielectric wall. The present study proposes a numerical method to estimate the EHD force by using experimental velocity information. Here, this method is used in a parametric study and the obtained results are compared with force balance measurements. It is shown that the EHD volume force increases in space and in amplitude for increasing voltage and increasing AC frequency. Furthermore the force distribution expands in an homothetic manner.