bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical modeling of a non‐linear viscous flow in order to determine how parameters in constitutive relations influence the entropy production
Authors: Müller Wolfgang H. , Abali B. Emek 
Published: December 2012

AbstractSome rheological materials, such as melting polymers, cosmetic creams, ketchup, toothpaste, can be modeled as non‐NEWTONian fluids by using a non‐linear constitutive relation. An incompressible flow of this kind of amorphous matter can be considered as a thermodynamic process, and a solution for the pressure, velocity and temperature fields describe it fully. Since such flow processes are generally irreversible, entropy is produced leading to dissipation in the system. This energy loss can be measured indirectly in a cone/plate viscometer which is used to determine viscosity of a BINGHAM fluid. While dissipation is an observable quantity we also want to be able to calculate it. Thus the goal of this work is to explain briefly how to compute a transient flow of a viscous fluid in two‐dimensional channel under a sinusoidal traction and calculate the dissipated energy for non‐NEWTONian fluids. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of Healing Processes in a Polymer Matrix
Authors: Specht Steffen , Bluhm Joachim , Schröder Jörg 
Published: December 2012

AbstractIn this article, a macroscopic 4‐phase model, based on the Theory of Porous Media, is presented to simulate healing processes in a polymere matrix. The healing process is described by the phase transition of two constituents, i.e., from liquid like healing agents to solid like healed material. As a first step, the healing mechanism begins at a certain time and is not driven by a healing criterion. A numerical example will be presented to demonstrate the applicability of the model in view of the description of healing processes. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modifications of hypergraphs of subsystems of mechatronic system as an effect of their analysis by means of different methods
Authors: Buchacz Andrzej 
Published: December 2012

AbstractPurpose of this paper is creating of the hypergraphs of the beam concerning of two methods of analysis of vibrating beam by the exact and approximate methods. This approach make possible to nominate the relevance or irrelevance between the characteristics obtained by considered methods – especially concerning the relevance of the natural frequencies‐poles of beams characteristics. The main subject of the research is the continuous free‐sliding (F‐S) beam as a subsystems of vibrating beam‐system. Findings this approach is a fact, that approximate solutions fulfill all conditions for vibrating beams and can be introduction to synthesis of these systems modeled by hypergraphs. Research limitation is that linear continuous transverse vibrating (F‐S) beam is considered. Practical implications of this study is the main point is the introduction to synthesis of transverse vibrating continuous beam‐systems. Originality of this approach considers the application Galerkin's method which concerns the analysis of beams and modeling them of transformed hypergraphs. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of different crack‐face boundary conditions on the dynamic intensity factors in linear magnetoelectroelastic solids
Authors: Wünsche Michael , Zhang Chuanzeng 
Published: December 2012

AbstractNew multifield materials for the development of smart devices and structures are receiving increasing attentions. Composite materials consisting of piezoelectric and piezomagnetic phases with an additional magnetoelectric coupling effect [1] offer advanced opportunities and may be used for broadband sensing, actuating devices and many other smart devices and structures which are required in engineering sciences. The dynamic crack analysis of magnetoelectroelastic solids is of special importance because such materials are often very brittle and the corresponding results have a direct relevance to the design and optimization of smart structures. The boundary element method (BEM) has been shown to be very attractive and efficient for solving dynamic crack problems in linear magnetoelectroelastic solids [3]. A critical issue in the numerical simulation of crack problems in linear magnetoelectroelastic solids is a realistic description of the mechanical and electromagnetical crack‐face boundary conditions, which is considered in this paper. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A projection method for phase field models in micromagnetics
Authors: Ethiraj Gautam , Miehe Christian 
Published: December 2012

AbstractMagnetic materials have been finding increasingly wider areas of application in industry and therefore, as indicated by the reviews [1], [2] and [3], there is an increased interest in the efficient modeling of such materials that have an inherent coupling between the magnetic and mechanical characteristics. A particular challenge in the modeling of such materials is the algorithmic preservation of the geometric constraint on the magnetization field, that remains constant in magnitude [4]. In earlier works, [5] and [6], we presented a phase field model within a geometrically exact incremental variational framework where the geometric property of the magnetization director is exactly preserved pointwise by nonlinear rotational updates at the nodes. In the current work however, we present an alternative approach that involves an operator split along with a projection step for the magnetization vector. This method provides significant advantages in terms of speed and ease of implementation at the cost of the maximum time step size used. The current work therefore presents comparative study of the the two methods. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental evaluation of phase velocities and tortuosity in fluid saturated highly porous media
Authors: Gueven Ibrahim , Kurzeja Patrick , Luding Stefan , Steeb Holger 
Published: December 2012

AbstractIn the current contribution, we present a novel method for the determination of the high frequency tortuosity parameter, α∞ in high porous media. Therefore, time‐domain measurements of ultrasonic signals are performed with a transmission technique. Aluminium foams with different pore fluids will be under the scope of experimental investigation. Finally, the experimental results are compared with analytical wave propagation tests. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical assessment of disorder effects in metal foam core sandwich beams based on a local homogenization procedure
Authors: Beckmann Carla , Hohe Jörg 
Published: December 2012

AbstractThe present study is concerned with a numerical procedure for prediction of uncertainty effects in sandwich structures with disordered cores. The approach is based on probability distributions of different material properties and their spatial correlation which are the results of the multiple homogenization analysis of testing volume elements. In order to illustrate the essential difference in the results of material uncertainties between computations using random fields and a deterministic approach both methods are applied to a single edge clamped sandwich beam with a metal foam core which is loaded by a force at the free end. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Data‐driven estimation of atomistic support for continuum stress using the Gaussian mixture model
Authors: Moran Sean J. , Ulz Manfred H. 
Published: December 2012

AbstractThe notion of stress being an inherent continuum concept has been a matter of discussion at the atomistic level. The atomistic stress measure at a given spatial position contains a space averaging volume over nearby atoms to provide an averaged macroscopic stress measure. Previous work on atomistic stress measures introduce the characteristic length as an a priori given parameter. In this contribution we learn the characteristic length directly from the atomistic data itself. Central to our proposed approach is the grouping of atoms with highly similar values of position and stress into the same atomistic sub‐population. We hypothesise that atoms with similar values for position and stress are those atoms which harbour the greatest influence over each other and therefore should be contained within the same space averaging volume. Consequently the characteristic length can be computed directly from the discovered sub‐populations by averaging over the maximum extent of each sub‐population. We motivate the Gaussian mixture model (GMM) as a principled probabilistic method of estimating the similarity between atoms within position‐stress space. The GMM parameters are learnt from the atomistic data using the Expectation Maximization (EM) algorithm. To form a parsimonious representation of the dataset we regularise our model using the Bayesian Information Criterion (BIC) which maintains a balance between too few and too many atomistic sub‐populations. We use the GMM to segment the atoms into homogeneous sub‐populations based on the probability of each atom belonging to a particular sub‐population. Thorough evaluation is conducted on a numerical example of an edge dislocation in a single crystal. We derive estimates of the space averaging volume which are in very close agreement to the corresponding analytical solution. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Selective Damping for Weakly Coupled FE‐MD models
Authors: Shan Wenzhe , Nackenhorst Udo 
Published: December 2012

AbstractWhen dynamic problems are of interest, the high‐frequency waves reflected from the coupling boundary will pollute the solution in the MD domain quickly and render the results from the multiscale model meaningless. In this contribution, we show that by applying artificial damping only to the high‐frequency part of the displacement field in the coupling domain in the weak coupling method can significantly reduce the reflections in the MD domain while not affecting the low‐frequency part that can be transmitted into the FE domain. The frequency analysis shows the errors in the magnitudes and phases of wave components are orders of magnitudes smaller than that in the bridging domain model or undamped weak coupling model. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plane stress finite element analysis of filler reinforced polymers
Authors: Sodhani Deepanshu , Reese Stefanie 
Published: December 2012

AbstractThe characteristics of polymers such as force‐deformation behaviour, strength, fatigue and wear resistance, can be tailored by embedding it with filler particles. The influence of the fillers on the material behaviour significantly depends on the size and geometric form of the filler aggregates, which vary under mechanical loading. The concept of super element is used to model filler particles. This is now coupled with the polymer matrix to generate a finite element model of filler reinforced polymers. In this work, we investigate the effect of filler geometry and volume fraction of fillers on the overall stiffness of the filler reinforced polymer. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale failure Modeling of composites using generalized finite element method
Authors: Pal Mahendra Kumar , Rajagopal Amirtham 
Published: December 2012

AbstractIn this work multiscale failure modeling of composites is made using generalized finite element method (GFEM). In this method the global approximation are constructed by combining the local basis with partition of unity functions. The enrichment functions for the GFEM approximation are computed using a proper orthogonal decomposition (POD) technique. The approximation is then used in a two scale Galerkin scheme for failure modeling of composites. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An insight into the rotational stall delay
Authors: Dumitrescu Horia , Vladimir Cardos , Frunzulica Florin 
Published: December 2012

AbstractBlade element momentum (BEM) theory which is based on the two‐dimensional (2D) aerodynamic properties of airfoil blade element is the most common computational engineering method for the prediction of loads and power curves of wind turbines. Although most BEM models yield acceptable results for high tip‐speed ratios where the local angles of attack are small, no generally accepted model exists up to date that consistently predicts the loads and power in stall regime for stall‐controlled turbines. Understanding of the stall delay phenomenon on wind turbines remains, to this day, incomplete. The lack of a conceptual model for the complex three‐dimensional (3D) flow field on the rotor blade, where stall is begins, how it progresses and where stall is practically terminated, has hindered the finding of a unanimously accepted solution. The paper aims at giving a better understanding of the delayed stall events and a reasonably simple correction model that complements the 2D airfoil characteristics used to a BEM method. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Allocation of the particle concentration for the SPH‐method
Authors: Stein Anika , Wünsch Olaf , Rütten Markus , Künemund Jens , Saalfeld Stefan 
Published: December 2012

AbstractIn this paper a method is presented to optimize the number of particles in three‐dimensional computations using the SPH method, based on the nearest neighbour. The process is presented for the breaking dam problem. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non isothermal simulation of non‐Newtonian flow in the shot sleeve of semi‐solid die casting processes
Authors: Laouar Roudouane , Wünsch Olaf 
Published: December 2012

AbstractThis work present a numerical study of the non isothermal flow of metal in the semi‐solid state in the shot sleeve of horizontal die casting machine during the injection process. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crude estimate of velocity distributions from Truckenbrodt's energy and momentum coefficients
Authors: Niessner Herbert 
Published: December 2012

AbstractOne of the simplest models for the velocity distribution in a pipe cross‐section dependent on two parameters consists of two layers of different thickness and velocity. Unfortunately relative thickness and velocity of the wall layer cannot be expressed analytically in terms of Truckenbrodt's energy and momentum coefficents. But relative thicknesses of a three‐layer model with wall and intermediate layer having opposite core and zero velocity can be. Reasonable in case of strong reverse wall flow only they allow a crude estimate of the parameters of the two‐layer model, which may then serve as initial values in computing them iteratively. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of bubbly flow in a vertical turbulent channel
Authors: Santarelli Claudio , Fröhlich Jochen 
Published: December 2012

AbstractThe paper presents results of Direct Numerical Simulation of bubbly flow to analyse the interaction between the turbulent fluid and the bubbles. The simulations aim to investigate the effect of the bubble Reynolds number, related to the bubble size, and the void fraction. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of bed load transport in turbulent open channel flow
Authors: Vowinckel Bernhard , Fröhlich Jochen 
Published: December 2012

AbstractThe paper reports on direct numerical simulations of a particle‐laden open channel flow carried out to investigate the interaction between the dispersed and the continuous phase. The dispersed phase is represented by an immersed boundary method. The particle‐particle collisions are accounted for by a physically motivated collision model. Two cases, one with shear stress below the threshold of mobilization and the other with shear stress above the threshold are considered. The different density ratios lead to different types of modification of the flow field by the formation of density‐specific patterns of the particles. Light particles do not attain resting states but saltate evenly distributed in span‐wise direction. Heavy particles tend to form stream‐wise clusters of inactive particles. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular dynamics simulation of lubricated contact between textured surfaces
Authors: Khromov Oleg , Shan Wenzhe , Nackenhorst Udo 
Published: December 2012

AbstractIn this contribution, the friction at atomical scale has been investigated by using molecular dynamics (MD) simulations. This work surves as a preliminary study on the influence of surface texture on the friction at atomic scale, where simple rectangular grooves are added to the contact surface. Our results suggest definite dependence of the friction on the orientation of the grooves, which decreases as the velocity increases. For a given velocity, an optimal direction of sliding which gives the minimum averaged friction coefficient can be identified. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature effects in thin droplets
Authors: Boettcher Konrad , Hötzel Jonas , Ehrhard Peter 
Published: December 2012

AbstractThin droplets spreading on a solid substrate are investigated, with a special focus on temperature effects. The aim is to manipulate the fingering instability which may occur in the spreading in a spin coating process. The analysis bases on lubrication approximation, valid for flat thin droplets, which usually is the case. The dynamic of the wetting is implemented by using a generalized law of Tanner, coupling the contact angle (CA) of the droplet at the (apparent) contact line (CL) with its speed. A one‐way coupling is used to investigate, whether viscous heating has to be taken into account. It can be derived that its role is negligible in the spreading process of a thin droplet, even for a relatively large viscous influence (large capillary number). Analyzing the results of a linear stability analysis of the fingering instability and taking Marangoni‐stresses (MS) into account reveals, that the instability may be suppressed by cooling the ambient gas or heating the substrate during the spreading. Unfortunately an comparison with experiments for spreading droplets in a heated gas shows deviations for larger spreading radii. The influence of temperature on density is investigated and on the way a criteria, from which it may be obtained whether a simple Boussinesq‐approximation (BA) is appropriate or not. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linearly implicit time discretization for free surface problems
Authors: Bänsch Eberhard , Weller Stephan 
Published: December 2012

AbstractDeeper investigation of time discretization for free surface problems is a widely neglected problem. Many existing approaches use an explicit decoupling which is only conditionally stable. Only few unconditionally stable methods are known, and known methods may suffer from too strong numerical dissipativity. They are also usually of first rder only [1, 9]. We are therefore looking for unconditionally stable, minimally dissipative methods of higher order.Linearly implicit Runge‐Kutta (LIRK) methods are a class of one‐step methods that require the solution of linear systems in each time step of a nonlinear system. They are well suited for discretized PDEs, e.g. parabolic problems [7]. They have been used successfully to solve the incompressible Navier‐Stokes equations [5]. We suggest an adaption of these methods for free surface problems and compare different approximations to the Jacobian matrix needed for such methods. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of sediment transport at the interface of a porous and a free flow domain
Authors: Reisner Timo , Steeb Holger , Renner Joerg 
Published: December 2012

AbstractSediment transport involves fluid flow in two different regions. In the free flow domain, the flow is governed by the viscous Newtonian fluid; sediment only occurs as suspended particles. In the porous domain however, the flow is governed by the pore geometry of the porous skeleton consisting of sedimented grains. In nature, the interface between these two domains is not a no‐slip boundary for the free flow. In this study, we quantify how sediment transport is affected by the interaction of the two different flows. We do this by comparing fluid flow in no‐slip bounded flow channels to fluid flow in channels containing both a free and a porous domain. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A VOF Method for Isobaric Expandable Flows
Authors: Shevchuk Illya , Rauschenberger Philipp , Janicka Johannes 
Published: December 2012

AbstractIn this paper a method is described to simulate isobaric multiphase flows at low Mach numbers with steep temperature gradients for fluids with non‐negligible thermal expansivity. Governing equations and solution procedure are outlined. Further, a test case is shown in order to verify the model. Single phase natural convection flows with large temperature differences and either constant or temperature dependent transport properties were simulated to prove the solution of coupled Navier‐Stokes and energy equations. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of a Nozzle‐Jet Configuration Including the Acoustic Near‐Field
Authors: Bühler S. , Kleiser L. 
Published: December 2012

AbstractA numerical simulation setup is presented which allows to study a circular jet flow configuration in which the nozzle is included in the simulation domain. Direct Numerical Simulations (DNS) are performed using up to 10th order compact finite‐difference schemes which are stabilized by applying a mild low‐pass filter. A parallelization approach has been implemented which shows good weak and strong scaling behavior. At the inflow the Synthetic Eddy Method is employed to generate turbulent fluctuations in the nozzle boundary layer with prescribed statistics, which are imposed by a sponge (forcing) layer technique. Simulation results for the jet flow field obtained at Reynolds number ReD = 19000 and a Mach number Ma = 0.9 as well as for the acoustic near‐field are found to be in good agreement with recent nozzle‐jet simulation results as well as experimental findings. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the impact of thermal sources on noise generation
Authors: Hahnenkamm A. , Masood R.M.A. , Münsch M. , Lienhart H. , Lopez E. , Zhou L. , Grilliat J. , Delgado A. 
Published: December 2012

AbstractSound emission is nowadays considered as a major environmental issue. The sound emission is generated, amongst other sources, due to an increasing amount of traffic and transport, i.e. road transport, rail and air traffic. Here, sound emission presents a significant risk to public health and a major cause of stress, especially in industrial countries. In this framework the present work is dedicated to the topic of active noise control with the target of noise reduction. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variation of friction drag via spanwise transversal surface waves
Authors: Meysonnat Pascal , Klumpp Stephan , Meinke Matthias , Schröder Wolfgang 
Published: December 2012

AbstractIntroducing spanwise velocity components into the near‐wall flow field of a turbulent boundary layer has shown to be an effective mean of influencing the wall shear stress. The underlying physical mechanisms leading to the drag reduction have however not been fully understood. The presented investigation uses sinusoidal transversal travelling surface waves to influence the near‐wall turbulence to achieve drag reduction. Two distinct wave configurations are analysed in detail and compared to an unactuated turbulent flat plate boundary layer flow to gain inside into the drag reducing mechanisms. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)