bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling Abrasive Wear Caused by Small Solid Particles of Different Sizes
Authors: Beck Florian , Eberhard Peter 
Published: October 2016

AbstractAbrasive wear is one of the mechanisms which cause the decrease of efficiency of hydraulic machines. The working fluid of a hydraulic machine, e.g., a turbine of a hydroelectric power plant, transports small solid particles of different sizes. Those small particles damage the surface of the hydraulic machine when contacting. In contrast to classical approaches in fluid dynamics, here, we present an approach where only mesh‐free methods are applied. The Smoothed Particle Hydrodynamics (SPH) method is used for modeling the fluid in this study. The SPH method is a mesh‐free method which has its advantages in describing transient fluid flows with free surfaces and large motions. The loading of the fluid consists of small solid particles of different sizes. A coupled approach for describing the loading is used. For the larger abrasive particles the Discrete Element Method and for smaller ones a transport equation is utilized. In doing so it is possible to model a loading of the fluid consisting of small particles of different sizes. The abrasive wear is described with an abrasive wear model. The wear model takes into account different parameters like the size, the velocity of the abrasive particles, and of course material parameters of both the target and the particles. On impact of an abrasive particle, the amount of removed material is stored at the boundary and in doing so the removed material over time is identified.In this work, a representative numerical example is presented. The simulations were performed with the code Pasimodo, developed at the Institute of Engineering and Computational Mechanics. It is the aim of this work to point out that it is possible to model abrasive wear due to abrasive particles with different sizes with a mesh‐free approach. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermo‐mechanically coupled modelling of cellular MgO‐C refractories under thermal shock
Authors: Bleistein Thomas , Jung Anne , Diebels Stefan 
Published: October 2016

AbstractRefractory materials such as magnesium oxide carbon (MgO‐C) composites are used in the steel‐making industry for furnaces, ladles or oxygen converters. A new class of composites are cellular MgO‐C materials, consisting of carbon foams filled with magnesium oxide and inclusions of gas filled pores. Cellular MgO‐C composites have the advantage of significantly improving the thermo‐mechanical properties [1]. This contribution focuses on the FEM implementation of a fully coupled thermo‐mechanical continuum model. It is based on the theory of porous media (TPM) restricted by a kinematic coupling of the displacement field of all constituents. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A thermo‐mechanical energetic cohesive zone model accounting for Kapitza interfaces
Authors: Esmaeili Ali , Javili Ali , Steinmann Paul 
Published: October 2016

AbstractThe objective of this contribution is to study computational aspects of modeling thermo‐mechanical solids containing mechanically energetic, geometrically non‐coherent Kapitza interfaces under cyclic loading. The interface is termed energetic in the sense that it possesses its own energy, entropy, constitutive relations and dissipation. To date, classical thermo‐mechanical cohesive zone models do not account for elastic interfaces. Therefore we propose a novel interface model that couples the classical cohesive zone formulation to the interface elasticity theory under the Kapitza assumption within a thermo‐mechanical framework. In other words, such an interface model allows for discontinuities in geometry, temperature and normal stress fields, while not permitting a jump in the normal heat flux across the interface. The equations governing a fully non‐linear transient problem are given. In particular, a comparison is made between the results of the classical thermo‐mechanical cohesive zone model and our novel (cohesive + energetic Kapitza) interface formulation. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of hydraulic fracture of porous materials using the phase‐field modeling approach
Authors: Heider Yousef , Markert Bernd 
Published: October 2016

AbstractIn this contribution, the numerical simulation of hydraulic fracture of fluid‐saturated porous materials is carried out on a continuum‐mechanical scale using the theory of porous media (TPM), extended by a phase‐field modeling (PFM) approach. Following this, behaviors such as crack nucleation and propagation, solid matrix deformation and interstitial‐fluid flow change from Darcy to Stokes‐like flow in the cracked region can be realized. Moreover, permanent changes of the local physics due to occurrence of the crack, such as of the volume fractions and the permeability, are taken into consideration. The mathematical modeling of this problem yields a strongly coupled system of differential algebraic equations (DAE). Thus, special descretization schemes for a stable and efficient solution are needed. To reveal the ability of the proposed model to simulate the important features of hydraulic cracking, a two‐dimensional example using the finite element method is presented. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Flexible C++ Framework for the Efficient Solution of Strongly Coupled Multifield Problems
Authors: König Marcel , Radtke Lars , Düster Alexander 
Published: October 2016

AbstractCoupled multifield problems occur in a wide variety of engineering applications. Due to the ever increasing available computational ressources, the numerical analysis of multifield phenomena has gained much interest in recent years. Partitioned solution strategies have been demonstrated to be a flexible and efficient way to solve even strongly coupled multifield problems. Major advantages of these approaches are the possibility to use different spatial and temporal discretizations for each of the subproblems and to employ existing, specialized solvers for their solution. In this work, we propose the software framework comana, which incorporates a partitioned solution strategy for the efficient numerical treatment of general multifield problems. Drawing on a highly modular architecture, comana greatly facilitates exchanging solvers and allows to easily implement tuned coupling algorithms. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical investigation of seismic attenuation in fluid‐saturated fractured media: An extended view of the Skempton coefficient
Authors: Pollmann Nele , Jänicke Ralf , Renner Jörg , Steeb Holger 
Published: October 2016

AbstractThe interpretation of data from seismic exploration gains from consideration of hydro‐mechanical processes in particular when the waves propagate through fluid‐filled fractured porous rocks. We specifically investigate attenuation processes in porous rock containing complex fracture networks with the main objective to identify effective hydro‐mechanical material properties by computational homogenization. To this end, we generate stochastic fracture ensembles and approximate fractures as ellipses with low aspect ratio (1/100). In other words, the fractures constitute thin and long hydraulic conduits with high permeability. Full periodic boundary conditions are employed on the small scale. We observe a strongly heterogeneous pressure propagation in the fracture network and the surrounding rock. The properties of the macroscopic substitute model are derived by means of a volume averaging technique. We identify a dependence of effective properties on fluid saturation and amount of fractures. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micromechanics of Electro‐ and Magneto‐active Soft Composites
Authors: Rudykh Stephan 
Published: October 2016

AbstractWe study the coupled behavior in soft active microstructured materials undergoing large deformations in the presence of an external electric or magnetic field. We focus on the role of the microstructures on the coupled behavior, and examine the phenomenon in the composites with (a) periodic composites with rectangular and hexagonal periodic unit cells, and (b) in composites with the random distributions of active particles embedded in a soft matrix. We show that for these similar microstructures exhibit very different responses in terms of the actuation, and the coupling phenomenon. Next, we consider the macroscopic and microscopic instabilities in the active composites. We show that the external field has a significant influence of the instability phenomena, and can stabilize or destabilize the composites depending on the direction relative to composite geometry. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Advanced FEM for free surface flow with application to landslides
Authors: Schauer Marco , Reinstädler Sven , Dinkler Dieter 
Published: October 2016

AbstractAn advanced space‐time finite element method is presented to investigate movements of landslides and their interaction with flexible structures. The mechanics of liquefied soil is described by Navier‐Stokes‐equations for visco‐plastic non‐newtonian fluid. Likewise the fluid the kinematics of the structure is described by velocities, taking large rotations into account. This leads to a monolithic fluid‐structure interaction approach considering the multi‐field problem as a whole. The discretized model equations are assembled in a single set of algebraic equations, which are solved by applying Newton‐Raphson scheme. Free surface motion of landslide is described by the level‐set method. To reduce computational effort the fragmented finite element method is used, where only active finite elements are evaluated. A pde‐based extrapolation of the velocity‐field is applied to ensure an accurate transport of distance function, which defines the profile in space and time of the free surfaces. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermomigration in Sn‐Pb solder bumps: Modelling and simulation
Authors: Schuß Stefan , Hesch Christian , Weinberg Kerstin 
Published: October 2016

AbstractIt is well known a homogeneous binary alloy subjected to a temperature gradient will become inhomogeneous. This decomposition phenomenon is called thermomigration or thermotransport or Soret effect, which is a cross‐effect in irreversible processes between heat conduction and atomic diffusion. In the present contribution we focus on a diffuse interface model for separation processes affected by temperature gradients coupled with a heat diffusion equation in order to describe thermomigration effects caused by joule‐heating. To be specific, we focus on phase separation in solder bumps consisting of tin and lead. Therefore we discuss the modelling of a Gibbs' configurational free energy density as well as the modelling of the chemical mobility, mobility of thermotransport and Dufour coefficient as sufficiently smooth functions in particle concentration and absolute temperature. The resulting set of partial differential equations involves spatial derivatives of fourth order. Consequently, the variational formulation of the problem mandates approximation functions which are at least C1‐continuous. In order to fulfill this requirement a B‐Spline based finite element scheme is provided. One of the main advantages of B‐Splines is the possibility to represent complex geometries exactly. However, it has been shown that especially curved B‐Spline geometries can not be treated in a straight forward manner in finite element analysis. For this reason we demonstrate the implementation of boundary conditions to avoid the arising numerical perturbations. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coupled simulation in vehicle engineering
Authors: Burger Michael , Schneider Fabio , Steidel Stefan 
Published: October 2016

AbstractModern vehicles are highly complex systems consisting of many subsystems in various physical domains, e.g. electric, electronic, hydraulic and control systems that dynamically interact. For any subsystem, there are tailored simulation tools with specifically developed and adapted numerical solvers. In this context, co‐simulation strategies are particularly attractive, where each submodel is solved with appropriate numerical methods. In industrial applications, one is hereby confronted with enormous numerical challenges with respect to efficiency, accuracy and numerical stability – especially in online applications. In this article, we present co‐simulation strategies by means of selected application examples from the field of vehicle engineering. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strongly‐coupled modelling and analysis of energy harvesting devices
Authors: Zilian Andreas , Ravi Srivathsan 
Published: October 2016

AbstractA monolithic approach is proposed that provides simultaneous modelling and analysis of the harvester, which involves surface‐coupled fluid‐structure interaction, volume‐coupled electro‐ mechanics and a controlling energy harvesting circuit for applications in energy harvesting. A space‐time finite element approximation is used for numerical solution of the weighted residual form of the governing equations of the flow‐driven piezoelectric energy harvesting device. This method enables time‐domain investigation of different types of structures (plate, shells) subject to exterior/interior flow with varying cross sections, material compositions, and attached electrical circuits with respect to the electrical power output generated. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Remarks on coupled multi‐scale simulations and high performance computation
Authors: Bartel Florian , Ricken Tim , Schröder Jörg , Bluhm Joachim 
Published: October 2016

AbstractTo describe material behaviour more precisely than nowadays, tomorrows simulation software will include multi‐scale homogenisation techniques. State of the art are various scale bridging strategies, like FE‐ODE, FE‐Phasefield or FE2‐Method. We are dealing with the FE2‐Method, see [3], [4], which gives us the possibility to take the geometric, discrete micro‐structure of a material into account. Furthermore, it allows to integrate enhanced continuum mechanical models. Here, we are researching on two‐scale approach with poro‐mechanical coupling based on the Theory of Porous Media (TPM), for more details see [1] or [2]. The framework is demanding and need a lot of computational effort. In order to receive industrial recognition, it is necessary to decrease the computation runtime. One way to go is definitely using high performance cluster. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homogenization of thermomechanical tread‐road contact for the investigation of tire rolling resistance
Authors: Beyer Robert , Nackenhorst Udo 
Published: October 2016

AbstractA homogenization framework for the stochastic average meso‐scale tread‐road interaction with emphasis on macro‐scale rolling resistance calculations is presented in this contribution. This framework accounts for large scale, high‐frequency penetration of tread rubber by the highest asperities as well as for the nonlinear thermo‐viscoelastic material behavior of this tread rubber in the regime of finite strains. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Computational Homogenization of Transient Diffusion Problems
Authors: Kaessmair Stefan , Steinmann Paul 
Published: October 2016

AbstractIn this contribution, we address the computational treatment of transient diffusion problems with heterogeneous microstructures using first‐order homogenization. There, we treat two different cases, firstly, when the transient part at the microscale can be neglected due to the vanishingly small size of the representative volume element (RVE) and secondly, when no steady state is reached at the microscale. This is the case when dealing with a relaxed version of the scale separation condition. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural optimisation of multiscale problems based on variational sensitivity analysis
Authors: Kijanski Wojciech , Barthold Franz‐Joseph 
Published: October 2016

AbstractThe contribution presents the essential steps for the extension of the well‐known FE2 method by elements from variational design sensitivity analysis. The derived sensitivity information for a given structure can be used to suggest improved designs using methods for structural optimisation with objective functions, constraints and design variables on multiple scales. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational Homogenisation using Reduced‐Order Modelling applied to Hyperelasticity
Authors: Soldner Dominic , Brands Benjamin , Zabihyan Reza , Steinmann Paul , Mergheim Julia 
Published: October 2016

AbstractWithin this study nonlinear reduced‐order modelling for hyperelastic material is applied for the boundary value problem on the micro‐scale which arises in the context of computational homogenisation. This involves the Proper Orthogonal Decomposition and the Discrete Empirical Interpolation Method for the nonlinear term. Considered error measures are the errors of the displacement field, the averaged stresses and the effective elasticity tensor. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling the effective permeability of microcracked materials using continuum and lattice micromechanics
Authors: Timothy Jithender J. , Meschke Günther 
Published: October 2016

AbstractUsing the framework of the mean‐field homogenization method, we propose a continuum and a lattice version of the cascade micromechanics model for the estimation of the effective permeability of microcracked materials. Estimates for the critical microcrack density below which the REV becomes effectively impermeable are derived for both the continuum and the lattice idealizations. A validation example that compares model predictions with direct numerical simulations for the effective permeability as a function of the microcrack volume fraction is provided. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerische Strömungsanalyse und Optimierung von Kraftwerksbuchten bei Laufwasserkraftanlagen
Authors: Ostermann Lars , Seidel Christian 
Published: October 2016

AbstractFür den wasserbaulichen Entwurf von Wasserkraftanlagen und ihre strömungsmechanische Optimierung werden neben dem rein auf Erfahrungswerten basierenden Entwurf vor allem experimentelle Untersuchungen am physikalischen Teilmodell oder Vollmodell im Wasserbaulabor eingesetzt. Strömungsmechanische Untersuchungen mit Hilfe numerischer Strömungsprogramme auf der Basis von 2D‐ und 3D‐Verfahren kommen teilweise zum Einsatz und stellen eine sinnvolle Ergänzung zu den experimentellen Verfahren dar. Für die Optimierung von Wasserkraftanlagen bieten sich schnelle numerische Lösungsverfahren an, die die Untersuchung einer größeren Anzahl von Optimierungsparametern und Strömungszuständen ermöglicht. Bei den 2D‐Verfahren eignen sich besonders Flachwassergleichungsbasierte Verfahren, da für diese Verfahren auf Grund ihrer weitverbreiteten Anwendung bei der Untersuchung strömungsmechanischer Fragestellungen im Wasserbau eine Vielzahl von Erfahrungswerten vorliegt, die häufig durch Insitu‐Messungen verifiziert sind. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impact of the regularity of the sediment bed on bed‐load transport
Authors: Jain Ramandeep , Vowinckel Bernhard , Fröhlich Jochen 
Published: October 2016

AbstractThe present study analyzes the impact of regularly arranged sediment bed on the particle clustering by introducing an artificial non‐uniformity in the particle packing. Two simulations only differing in their sediment bed configuration are reported with the non‐uniform roughness created through a random vertical displacement of the fixed particles constituting the rough wall. It is found that the irregular roughness enhances particle clustering as well as bed‐load transport compared to the case of uniform roughness. As a result the statistics of disperse and continuous phase are markedly different. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhanced mass transfer in micro‐capillary two‐phase flow
Authors: Lakshmanan Peter , Ehrhard Peter 
Published: October 2016

AbstractProcess design of multi‐phase unit operations on the micro‐scale relies on the detailed knowledge of the hydrodynamics and mass transfer of discrete disperse fluid particles. The present work examines gas bubbles in micro‐capillaries. For the case of bubbles rising in vertical capillary, the hydrodynamics and concentration fields are determined over a wide field of parameters (Re, Sc, dbubble/dcapillary) using a combination of level‐set and body‐fitted mesh methods. Drag coefficients and Sherwood numbers are computed from the results and can be used to derive empirical correlations for each parameter and mode of operation. These correlations allow for the individual optimization of the mass transfer process in micro‐capillaries. The results are compared to experimental data and available correlations in literature with generally good agreement. It can be shown that mass transfer can be enhanced by using small geometries like micro‐capillaries. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerische Modellierung der Freispiegelströmung am Beispiel eines Kreissegmentschützes
Authors: Schippke Hans‐Henning , Seidel Christian , Dinkler Dieter 
Published: October 2016

AbstractEs wird ein Berechnungsmodell vorgestellt mit dem eine numerische Analyse der Überströmung von Verschlussorganen möglich ist. Der Arbeitsschwerpunkt liegt auf der Untersuchung der Stabilität des Lösungsverfahren unter Berücksichtigung der zu wählenden komplexen Randbedingungen sowie der physikalischen und numerischen Parameter. Die Güte der dabei gewonnen Ergebnisse wird mit experimentellen Untersuchungen abgeglichen. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the flow around Glauert‐Goldschmied body in the narrow channel and separation control strategy
Authors: Procházka Pavel , Uruba Václav 
Published: October 2016

AbstractPreviously, there was tested a wire dielectric barrier discharge (DBD) plasma actuator to generate sufficiently strong ionic wind to affect freely developed boundary layer in the narrow channel. This paper will report about next step – to installation of actuator inside a streamlined body. The experiment will take place inside perspex rectangular (250 × 100 mm) channel and main task is to find the appropriate place for actuator fitting for three different flow regimes. Hence, the separation point and recirculation area will be investigated via PIV anemometry for base case and for active flow control methods (e.g. plasma actuator) as well as frequency spectrum of the flow will be evaluated to describe the nature of the flow. The measurement plane will be perpendicular to the bottom of the channel and in longitudinal level. These essential information will be used for actuator design, actuator embedding and to tune actuator frequency in order to suppress the recirculation area as much as possible. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Hahn polynomial expansion of a continuous function of bounded variation
Authors: Goertz René 
Published: October 2016

AbstractWe consider the well‐known method of least squares (cf., e.g., [1, p. 217]) on an equidistant grid with N + 1 nodes on the interval [−1, 1]. We investigate the following problem: For which ratio N/n, do we have pointwise convergence of the least square operator LSNn : C[−1,[1][→[Pn? To solve this problem we investigate the relation between the Jacobi polynomials Pα,βk (cf., e.g., [2, p. 216]) and the Hahn polynomials Qk (·; α, β, N) (cf., e.g., [2, p. 204]). In particular, we present the following result: Let f ∈ {g ∈ C1[−1, 1] : g′∈ BV [−1, 1]} and let (Nn)n be a sequence of natural numbers with n4/Nn → 0. Then the least square method LSNn [f] converges for each x ∈ [−1, 1]. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)