bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Non‐newtonian Flow Behavior on Local Hemodynamics
Authors: Perktold K. , Karner G. , Leuprecht A. , Hofer M. 
Published: March 2011

AbstractThe influence of non‐Newtonian blood flow in large arteries is studied numerically. The model studies are carried out to demonstrate the shear thinning effect at increased shear rates resulting from the reversible destruction of red blood cell aggregates and to show basic viscoelastic effects. The mathematical models considered use the conservation of momentum and of mass and constitutive relations describing the shear thinning behavior and relations of Jeffreys type (Oldroyd‐B model). The numerical approach applies the finite element method. The non‐Newtonian inelastic effects are demonstrated in a curved tube model and in an anatomically and physiologically realistic artery bifurcation model. The viscoelastic flow study is carried out using an axisymmetric tube with a local constriction modeling a stenosed blood vessel. The assumption of physiologically realistic shear thinning behavior shows a minor quantitative influence on local flow patterns compared with Newtonian reference flow.
Modelling Finite Deformation of Polycrystals Using Local Objective Frames
Authors: Forest S. , Pilvin P. 
Published: March 2011

AbstractThe formulation of constitutive models at finite strain using local objective frames is applied to solids with microstructure. Priviledged space frames are introduced at both the material level and the micro structure level. For single crystals, the method leads to a model almost equivalent to Mandel's theory. For polycrystals, an explicit concentration rule written in the corotational frame is proposed. Simulations of texture evolutions are then presented.
Experimentelle Untersuchungen der Nachlaufströmung eines stumpfen Körpers mit einfacher Geometrie
Authors: May F. , Schwarz V. 
Published: March 2011

AbstractDie Nachlaufströmung eines Grundkörpers mit rundem Querschnitt und stumpfem Heck wurde mit Windkanalmessungen experimentell untersucht. Ferner wurden die Wirkungen von Maßnahmen im Nachlauf des Körpers auf den Widerstand des Körpers und auf die Wirbeldynamik dm Nachlauf analysiert. Bei den untersuchten Maßnahmen handelte es sich um eine kreisförmige Nachlaufscheibe, die parallel zur Basisfläche angeordnet war und um ein Gleichrichterkreuz. Die Widerstandsbeiwerte des Körpers in den verschiedenen Konfigurationen wurden mittels ei‐ner Windkanalwaage ermittelt. Die Wirbeldynamik wurde unter Verwendung von Hitzdrahtmessungen im Nachlauf des Körpers analysiert. Dazu waren acht Hitzdrahtsonden kreisförmig im Nachlauf angeordnet. Zusätzlich wurden mit Hitzdrahtsonden in gerader Anordnung die zeitlich gemittelten Nachlaufdellen der einzelnen Konfigurationen bestimmt. Die Messungen zeigten, daß sowohl mit der Nachlaufscheibe als auch mit dem Gleichrichterkreuz eine Widerstandsreduktion erzielt wird, die Auswertung der Hitzdrahtmessungen ergab jedoch, daß die Wirkungsprinzipien dieser Maßnahmen völlig unterschiedlich sind.
Comparison of the tangent model predictions to finite element results for the solution of the inclusion problem in viscoplasticity
Authors: Molinari A. , El‐Houdaigui F. , Tóth L. S. 
Published: March 2011

AbstractUsing the tangent viscoplastic model of Molinari, Canova and Abzi (1987) in its general anisotropic formulation, the strain localisation behaviour of spherical inclusions is examined for the case of von Mises type viscoplastic creep. The obtained results are compared to the finite element results of Gilormini and Germain (1987) and good agreements have been obtained.
Finite Element Modeling of 3D Elastic‐Elastic Rolling Contact
Authors: Nackenhorst U. , Zastrau B. W. , Jarewski J. 
Published: March 2011

AbstractThe three dimensional rolling contact of elastic bodies is simulated numerically by a finite element approach. The relative kinematics is described by an Arbitrary Lagrangian Eulerian description. Special emphasis has to be laid onto the tangential contact condition because the slip, i.e. the relative tangential displacement of the contacting particles, is not obtained a priory. Numerical examples from the railway wheel rolling on the rail underline the applicability of the suggested method.
On Smooth Finite Element Discretizations for Frictional Contact Problems
Authors: Wriggers P. , Krstulovič‐Opara L. 
Published: March 2011

Abstract2D frictional polynomial node to segment contact elements are developed using the Mathematica SMS (Symbolic Mechanics System) package. The weak formulation and the penalty method are used for the description of large deformation frictional contact problems. Presented approach, based on non‐associated frictional law and elastic‐plastic tangential slip decomposition, is resulting into the quadratic rate of convergence within Newton‐Raphson iteration loop.
Resonant wave response to obstacle forcing in two layer fluid flow
Authors: Cox E. A. , Kluwick A. , Scheichl S T. 
Published: March 2011

AbstractThe paper is concerned with the propagation of weakly nonlinear gravity waves in a two layer fluid over bottom topography when the fluid is assumed to be inviscid and incompressible. Specifically, we investigate disturbances of a homogeneous critical state. As a consequence, the resulting (free surface or internal) wave is trapped which leads to a resonant wave response to obstacle forcing. In general the wave motion is found to be governed by a kinematic wave equation with quadratic nonlinearity where the bottom topography enters as a source term. In the case of internal waves, however, there exists a flow regime in which both quadratic and cubic nonlinear terms have to be taken into account.
Constitutive relations for thermo‐elastic porous solids
Authors: Bluhm J. 
Published: March 2011

AbstractBused on the theory of porous media (TPM), constitutive relations for the so‐called “effective” stresses of the thermo‐elastic compressible or incompressible solid phase of a fluid saturated or an empty porous solid will be presented. For the description of a compressible solid within the framework of finite deformation processes, well‐known constitutive laws for one‐component materials can be used. For incompressible porous solids, one has to consider that the so‐culled compression point exists (in this point all pores are closed and no further volume compression can occur). With respect to the description of the aforementioned effect, constitutive relations for incompressible solids are developed following the structure of the constitutive laws for compressible solids.
Application of Minkowski Space to Description of Anisotropic Pore Space Structure in Porous Materials
Authors: Cleszko M. 
Published: March 2011

AbstractThe subject of this note is the modelling of an anisotropic pore space structure in rigid porous materials capable of fluid flow through its pores. In this paper, the new macroscopic model of a saturated porous medium is proposed in which a fluid flow through porous skeleton of an anisotropic pore structure is considered as a motion of the material continuum in the plane anisotropic metric space ‐ Minkowski space ‐ immersed in a Euclidean one that is used as the model of the physical space. This model takes into consideration the fundamental fact, concerning kinematics of a fluid‐saturated porous solid, that the pore space of permeable skeleton forms the real space for a fluid motion and its structure imposes restrictions on that motion.The metrics of Minkowski and Euclidean spaces are applied in the paper to determine the respective measures of any line, surface, and volume elements. The new metric tensors of surface and volume elements in these spaces have been proposed that are directly related to the metric tensors of distance. This enables one to define the geometrical parameters characterising pore structure of such materials.: the tortuosity, the volume, and surface porosity. It has been shown that the structure of isotropic pore space of porous materials is described only by two independent scalar parameters.
A contact zone approach for an interface crack in a piezoelectric anisotropic bimaterial
Authors: Loboda V. V. , Herrmann K. P. 
Published: March 2011

AbstractAn exact analytical solution for an interface crack with an artificial contact zone situated between two piezoelectric semi‐infinite spaces has been found. The classical interface crack model and the contact zone model can be obtained as particular cases of this solution. Analytical relationships between the fracture mechanical parameters of these different models are given. On the base of these relations a numerical algorithm has been developed for the determination of fracture mechanical parameters at an interface crack tip situated in the material interface of a finite‐sized anisotropic piezoelectric bimaterial.
An Asymptotic Method for Effective Properties of Visco‐Elastic Composite Materials
Authors: Aadrianov I. V. , Danishevs'kyy V. V. , Toearzewski S. 
Published: March 2011

AbstractWe consider visco‐elastic two‐components composite materials, consisting of an infinite regular arrays of fibers inclusions embedded in a matrix. Analytical formulas for Laplace transforms of the effective shear relaxation and creep functions are derived. For this aim an asymptotic technique, based on the homogenization method, the three‐phase model, the method of boundary perturbation, Pade and quasifractional approximants, is used Obtained results also allow us to evaluate the effective complex shear modulus and loss tangent for stationary harmonic oscillations of considered composite material. Derived solutions are valid for all values of the components concentrations and properties. Our method may be effectively used for determining various effective properties of visco‐elastic composite materials with different inclusions geometries.
State Diagram of fine cohesive powders at zero shear
Authors: Castellanos A. , Valverde J. M. , Watson P. K. 
Published: March 2011

AbstractWe present measurements of the tensile strength for a set of model toners, with a typical diameter of 10 microns, as a function of the consolidation stress and void fraction. The technique used to change the consolidation state is to centrifuge the powder. For each consolidation state the tensile strength is measured by subjecting the powder to a tensile stress by means of a direct gas flow. The average free volume is calculated by measuring the powder bed height by means of an ultrasonic device. All these processes allow us to draw the State Diagram of the powder at zero shear. The influence of the hardness, and size of the asperities, both controlled by flow control additives, as well as the influence of the radius of the particle, is determined, We find that, contrary to the case of low consolidations where the tensile strength was a linear function of the consolidation stress, at high consolidation stresses the tensile strength is a sublinear function of the compressive stresses.
Numerical Study of the Flow of Sheet Metal Between Circular Drawbeads
Authors: Courvoisier L. , Martiy M. , Ferron G. 
Published: March 2011

AbstractThis paper analyses the evolutions of stresses and strains for a sheet metal band plastically deformed along a drawbead. Numerical simulations are conducted to model the process of drawing and to study the mechanics of drawbead process of drawing and to study the mechanics of drawbead restraint.
Stress‐induced martensitic transformation in polycrystalline alloys
Authors: Patoor E. , Entemeyer D. , Eberhardt A. , Berveillxr M. 
Published: March 2011

AbstractModern scale transition methods developed in mechanics of materials these last years are successfully applied to model the particular behaviour exhibited by shape memory alloys. Starting from a local kinematical analysis based on crystallographic considerations and determining the thermodynamical forces associated to the martensitic phase transformation local relationships are determinde using the self‐consistent approximation. This framework is applied to simulate different loading conditions using mechanical of thermal loading paths with uniaxial of multiaxial conditions. Results such obtained are compared with experimental results.
Pseudoelastic NiTi‐Alloys under Cyclic Loading
Authors: Schmidt I. , Lammerling R. 
Published: March 2011

AbstractIn addition to the shape memory effect, shape memory alloys show two further properties that are useful for mechanical applications: pseudoelasticity and a very high damping capacity compared to other metals. Beside the temperature both characteristics depend on the amplitude and rate of the mechanical load, as well as on the load history. In cyclic tensile tests the mechanical behaviour of binary NiTi‐alloys is investigated in order to make use of them in engineering applications.
The ε‐Relaxed Approach in Topology Optimization for Various ε Functions
Authors: Kutylowski R. 
Published: March 2011

AbstractThe inspiration of this contribution was a paper written by Cheng and Guo ]1[ where the E‐relaxed approach for structural topology optimization was applied and a second one paper by Duysinx and Bendsoe ]2[ where continuum structure with stress constraints was considered. In this contribution various ε functions are proposed and discussed for continuum structure from the convergence point of view. The problem is illustrated by FEM examples.
Temporal Commutation Errors in Large‐Eddy Simulation
Authors: Franke J. , Frank W. 
Published: March 2011

AbstractThe spatial filtering applied in large eddy simulations leads to additional closure problems if the filter width varies in space and time. While the spatial commutation error has been examined, the temporal commutation error has not been studied, despite its relevance for in‐cylinder flow simulations ]1[. Here some theoretical results for the temporal commutation error are presented. It is shown that a temporally varying domain leads to an additional constraint on the filter function. The results are illustrated for a simple scalar problem.
On the Distribution of the Zeros of Polynomials Related to the Daubechies Wavelets
Authors: Boese F. G. 
Published: March 2011

AbstractTo locate all zeros of the polynomials qn(z) from (1) as precise as possible is our aim. These polynomials are related to the sequence of Daubechies wavelets. Zero enclosures up to a separation of all zeros are communicated. The enclosing sets are conformal lemniscate rectangles.
The Two‐Sided Lid‐Driven Cavity: Aspect‐Ratio Dependence of the Flow Stability
Authors: Blohm C. , Albensoeder S. , Kuhlmann H. C. , Broda M. , Rath H. J. 
Published: March 2011

AbstractThe transition from two‐dimensional (2D) steady to three‐dimensional (3D) flow is investigated experimentally in a two‐sided lid‐driven cavity for anti‐parallel motion of two facing walls. Both wall speeds (Reynolds numbers) have the same absolute value. We present critical Reynolds numbers at the onset of steady three‐dimensional flow as a function of the cross‐sectional aspect ratio. The critical curve is composed of different neutral branches belonging to different instability modes. Comparison with numerical results enables insight into the corresponding mechanisms.
Linear Stability Theory of Non‐Isothermal Flow Between Two Rotating Disks
Authors: Tuliszka‐Sznitko Ewa , Soong Chyi‐Yeou 
Published: March 2011

AbstractThe objective of the present study is to investigate the flow stability of mixed convection in non‐isothermal rotating fluids between a rotating disk and a stationary one. The buoyancy effects stemmed from the rotational forces, including centrifugal and Coriolis, are taken into account. A similarity model of thermal flow with the assumption of Boussinesq fluids is formulated for generating axially symmetric solutions of the basic state. Disturbance equations are derived by using the concept of small perturbation of normal mode expressions, and then solved by the Chebyshev collocation spectral method. The influences of the rotation‐induced buoyancy effects and the rotational conditions on the flow stability characteristics of the two‐disk rotating fluid motion are explored. The present results disclose the mechanisms and the significance of the rotation‐induced buoyancy on flow stability characteristics of the non‐isothermal fluids in the rotor‐stator disk systems.
Creeping Newtonian Film Flow Down an Inclined Wavy Plane. Part II
Authors: Wierschem A. , Scholle M. , Aksel N. 
Published: March 2011

AbstractWe consider the creeping film flow down an inclined wavy plane. For large wavelengths and thin films we consider two different approaches depending on the order of the amplitude of the wavy bottom profile and compare them to experimental results.
Heat transfer from hot wires at small forced‐flow velocities
Authors: Henselowsky C. , Kuhlmann H. C. , Rath H. J. 
Published: March 2011

AbstractAt very low velocities (v ≤ 0.1 m/s), hot‐wire measurements are significantly influenced by free convection. To assess the contribution of free‐convection heat transfer to the heat balance of hot‐wire probes, measurements under gravitational and under microgravity conditions are compared in a velocity range 0 ≤ v ≤ 0.3 m/s corresponding to a Reynolds number range Re ≤ 0.1. The measurements were made with horizontal hot‐wire probes in cross flow in air at 21.8°C. For creeping flow three distinct regions can be observed in which different factors dominate the heat transport. While free convection prevails at Re = 0, forced convection dominates for Re > Gr1/3. At intermediate Reynolds numbers both transport mechanisms must be considered.
Stability of thermocapillary flow in cylindrical liquid bridges: Rotation of the hot disk
Authors: Lee Y.‐S. , Kuhlmann H. C. , Rath H. J. , Chun Ch.‐H. 
Published: March 2011

AbstractThe thermocapillary flow in a differentially heated cylindrical liquid bridge under steady rotation of the hot disk is considered in the limit of zero capillary number. Steady flow states and their three‐dimensional stability are calculated numerically. It is shown that the vortex breakdown caused by the rotation is strongly affected by the thermocapillary flow. A linear stability analysis reveals that the most dangerous perturbations are oscillatory with azimuthal wavenumber m = 1 or m = 2 depending on the parameters.
Combustion of the Diesel Fuel Spray
Authors: Marcic M. , Zgonik M. , Avsec J. 
Published: March 2011

AbstractThe paper deals with the computer simulation of the Diesel fuel spray combustion under the similar conditions as in Diesel engines. A mathematical model of the spray propulsion and combustion is treated which allows the observation of the phenomena in the spray during its movement through air. Fuel droplets of the spray are vaporized due to the transfer of heat from hot air. In a certain moment when required conditions are met selfignition of mixture occurs. In order to determine the points where selfignitions occurs first, we have introduced the term “ignition probability” referring to the local air ratio and fuel dispersion in the spray.
Schalltransmission durch Isolierfenster
Authors: Langer S. , Antes H. 
Published: March 2011

AbstractDer Nachweis der Schalldämmwirkung von Isolierfenstern erfolgt bisher im Allgemeinen durch Messungen unter normierten Bedingungen, obwohl eine numerische Simulation schneller und effektiver wäre. Deshalb wird dafür hier ein Berechnungsmodell entwickelt, dass die Schallwellenausbreitung und den Schalldurchgang durch zweifach‐verglaste Fenster sowie alle auftretenden dynamischen Wechselwirkungsvorgänge beinhaltet.Dazu wird sowohl für die Biegewellen der als elastische, dünne Kirchhoff‐Platten modellierten Glasscheiben wie für die Schalldruckwellen in der Luft der Scheibenzwischenräume und des Gebäudeinnenraums die Finite‐Element‐Methode (FEM) verwendet. Die Umgebung ausserhalb des Gebäudes stellt ein halbunendliches Gebiet dar, so dass wegen der Abstrahlbedingung dort die Randelementmethode (REM) bevorzugt wird. Die Kopplung der Fluidgebiete mit den Glasscheiben erfolgt jeweils über die virtuellen Arbeiten an den Koppelflächen. Die Lösung liefert sowohl das dynamische Verhalten der Glasscheiben wie die Schalldruckverteilung in der Luft. Damit ist dort der Schallpegel bekannt und kann das Schalldämm‐Maß des Fensters ermittelt werden.
Hochgenaue Konturliniengenerierung
Authors: Callies M. , Callies R. 
Published: March 2011

AbstractAutomatisierte Meßverfahren tasten Gegenstände mit hoher Genauigkeit ab. Die entstehenden Datenmengen sind für eine direkte Weiterverarbeitung in FE‐Programmen zu umfangreich. Ein datenreduzierender, auf multivariates, NURBS basierender Ansatz wird vorgestellt, mit dem sich Konturkurven und‐flächen mit hoher Präzision aus Meßwerten ableiten lassen. Die Approximationsqualität wird zur strikt an die Größe der Meßfehler angepaßten mathematischen Nebenbedingung, unter der die primären Zielfunktionale zu optimieren sind. Lokal adaptive Verfeinerungen erhöhen signifikant die Flexibilität der Ansätze. Alle Schritte unterliegen einer strikten Optimierung über SQP‐Verfahren. Beispielhaft wird die automatische Präzisionsauswertung von Schichtbildern aus der Computertomographie vorgestellt. Man erreicht Approximationsgenauigkeiten der Konturlinien von 0.05 mm bei einer Datenreduktion um mehr als den Faktor 5.
Numerical analysis of the polygonalization of railway wheels
Authors: Langemann Dirk 
Published: March 2011

AbstractThe formation of irregular wear patterns on wheels in high‐speed trains is an important problem because it affects negatively the convenience of passengers and increases maintenance costs. Finally, nonhomogeneous contact geometry leads to considerable variations of loading conditions and is hence a security hazard.An algorithm is presented to analyze the development of irregular wear patterns quantitatively and to predict wear formation of wheel/rail‐systems. It is based on the concept of ergodicity and it is time‐expensive but reliable. The algorithm is applied on a 3D‐model using different parameters.
Neighbourhood immigrant acculturation and diet among Hispanic female residents of New York City
Authors: Park Yoosun , Neckerman Kathryn , Quinn James , Weiss Christopher , Jacobson Judith , Rundle Andrew 
Published: March 2011

AbstractObjectiveTo identify predominant dietary patterns among Hispanic women and to determine whether adherence to dietary patterns is predicted by neighbourhood-level factors: linguistic isolation, poverty rate and the retail food environment.DesignCross-sectional analyses of predictors of adherence to dietary patterns identified from principal component analysis of data collected using the Study of Women's Health Across the Nation FFQ. Census data were used to measure poverty rates and the percentage of Spanish-speaking families in the neighbourhood in which no person aged ≥14 years spoke English very well (linguistic isolation) and the retail food environment was measured using business listings data.SettingNew York City.SubjectsA total of 345 Hispanic women.ResultsTwo major dietary patterns were identified: a healthy dietary pattern loading high for vegetables, legumes, potatoes, fish and other seafood, which explained 17 % of the variance in the FFQ data and an energy-dense dietary pattern loading high for red meat, poultry, pizza, french fries and high-energy drinks, which explained 9 % of the variance in the FFQ data. Adherence to the healthy dietary pattern was positively associated with neighbourhood linguistic isolation and negatively associated with neighbourhood poverty. Presence of more fast-food restaurants per square kilometre in the neighbourhood was significantly associated with lower adherence to the healthy diet. Adherence to the energy-dense dietary pattern was inversely, but not significantly, associated with neighbourhood linguistic isolation.ConclusionsThese results are consistent with the hypothesis that living in immigrant enclaves is associated with healthy dietary patterns among Hispanics.