bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical modeling of elliptical cylindrical shells, containing flowing fluid
Authors: Bochkarev Sergey , Lekomtsev Sergey , Matveenko Valery 
Published: November 2013

AbstractThe paper presents a finite‐element algorithm for investigation of the dynamic behavior of elastic shells with arbitrary cross sections containing a flowing fluid. A curvilinear surface of the structure is approximated by a set of plane elements, which are subjected to both membrane and bending forces. Description of the shell motion is based on the variable principle of virtual displacements, which includes the linearized Bernoulli equation for calculation of hydrodynamic pressure. A compressible non‐viscous fluid is considered in the framework of the potential theory, the equations of which are transformed with the use of the Bubnov‐Galerkin method. The performance of the algorithm is demonstrated by the example of two shells with a circular and elliptical cross section. Numerical simulation have been carried out to analyze the influence of the ratio of the ellipse semi‐axes, the linear dimensions of the structure and the level of shell filling on the hydrodynamic stability of the connected “shell‐fluid” system. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear Modeling of the Elastic Beam with Different Order Couplings
Authors: Luu Quang Khanh , Söffker Dirk 
Published: November 2013

AbstractNew structures become larger, lighter, and slender in practical applications. The problem of large elastic deformations undergoing overall motion in these structures has to be considered in the dynamic modeling. Using descriptions considering the nonlinear strain displacement relationships, the couplings between overall motions and the flexible deformations can be taken into account. Several approaches exist in the literature, but are not compared. These models are briefly introduced and explained with respect to the above mentioned problem. Effects of different couplings of different order combining nonlinear kinematics and higher order kinetics of flexible deformations are therfore investigated systematically. The results allow a deep insight and therfore understanding of related effects. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A cap model for soils featuring a smooth transition from partially to fully saturated state
Authors: Gamnitzer Peter , Hofstetter Günter 
Published: November 2013

AbstractSoils consist of a porous soil skeleton filled by fluids like air and water. The accurate description of their mechanical behaviour requires a coupled solid‐fluid approach. The analysis is based on a set of balance equations, kinematic equations and constitutive equations, the latter including a material model for the soil. Depending on the degree of saturation, the soil behaviour has to be modelled in both, partially and fully saturated state. We present a constitutive model for soils developed from the cap model proposed by Kohler and Hofstetter. The elasto‐plastic model is formulated in terms of two independent stress variables, generalised effective stress σij☆ and matric suction pc. It is applicable to partially and fully saturated state. The yield surface includes a shear failure envelope and a hardening cap surface. Its evolution in terms of matric suction is controlled by the load collapse (LC) yield curve and parameters defining the suction‐dependent intersection of the shear failure envelope with the 1☆‐pc‐plane, where 1☆ = tr(σij☆). Our extension of the model includes an improved LC yield curve to enable a better representation of wetting/drying paths and to allow a smooth transition from partially to fully saturated state. Numerical results for a low to medium plasticity clay are in good agreement with experimental data. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Predicting the onset of delamination in layered fiber‐reinforced composites
Authors: Simon Jaan‐Willem , Stier Bertram , Reese Stefanie 
Published: November 2013

AbstractIn this paper, composite structures are considered which consist of several layers of carbon fiber reinforced plastics (CFRP). For such layered composite structures, delamination constitutes one of the major failure modes and hence predicting its initiation is essential for their design. Evaluating stress‐strength relation based onset criteria requires an accurate representation of the through‐the‐thickness stress distribution, which can be particularly delicate in the case of shell‐like structures. Thus, in this paper, a solid‐shell finite element is utilized, which allows for incorporating a fully three‐dimensional material model, still being suited for application to thin structures. Moreover, locking phenomena are cured by using both the EAS and the ANS concept, and numerical efficiency is ensured through reduced integration. The proposed anisotropic material model accounts for the material's micro‐structure by using the concept of structural tensors. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Heat Transfer in Rotor/Rotor and Rotor/Stator Cavity: Physics, Correlations and Numerical Modeling
Authors: Kielczewski Kamil , Tuliszka‐Sznitko Ewa 
Published: November 2013

AbstractThe transitional and turbulent flow in the near wall sublayer is now mostly modeled based on the existing knowledge of simple 2D flows. To determine the effect of three dimensionality on the turbulent flow structures and turbulent heat transfer in the near wall areas the authors investigate numerically (SVV) turbulent flow in rotor/stator and rotor/rotor flows (with and without axial throughflow). These simple model flows contain most of the phenomena that are needed to understand more complex, 3D transitional and turbulent flows. Attention is focused on the turbulent characteristics which should have more universal character. To stabilize calculations for high Reynolds numbers (up to Re=800 000) the SVV operator is introduced into the Navier‐Stokes and energy equations solver for cylindrical coordinate system without using complex numbers. Code optimization and parallelization have speeded up computations 20 times. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear Homogenization of Microstructures in Steel with Temperature‐Controlled Phase Transformation
Authors: Neumann Rudolf , Böhlke Thomas 
Published: November 2013

AbstractFor the description of the phase transformation effect TRIP (transformation induced plasticity), a thermo‐micro‐mechanical model is introduced. The scale transition is realized by a Hashin‐Shtrikman type homogenization scheme. The macroscopical behavior is purely based on micro‐mechanical, thermo‐mechanical constitutive models. The model takes into account the thermal strains arising during cooling, and the Greenwood‐Johnson effect. The Greenwood‐Johnson effect describes the TRIP strain developing during the growth of a product phase in the parent phase. The TRIP strain is determined by a micromechanical model gained by an extended Leblond ansatz. For the diffusion driven phase transformation, the JMAK model is incorporated into the homogenization scheme. The diffusionless transformation is described by a rate law of Koistinen‐Marburger type. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some experimental results on flow in a diverging 2D channel
Authors: Antoš Pavel , Hladík Ondřej , Jonáš Pavel , Uruba Václav 
Published: November 2013

AbstractThe effect of the free stream turbulence (FST) on the essential flow characteristics was investigated in the diverging 2D channel. The diverging channel was modelled in the closed type working section by fastening a displacement body above the flat plate that is parallel with the wind‐tunnel axis. The angle of the channel expansion 11 degree induced the pressure gradient parameter $K = \nu (dU_0/dx)/U_0^2 \approx 0.16 \div -0.28$ with the flow velocity U0 30 m/s at the start of expansion, x = 0. The height of the channel is 0.15 m at x = 0. FST was either natural 0.3 percent or amplified by turbulence generating grids/screens with turbulence levels up to 5 percent. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Simulation of the Ising Surfaces of the Cylinder and Profile
Authors: Alekseyenko Sergey 
Published: November 2013

AbstractThe basic models and research methods of airfoil icing processes, meteorological parameters, types of clouds, types of ice and their influence on aerodynamic performance are analyzed. For description of impinging water droplets on the surface are used: model of interpenetrating mediums, trajectory model and homogeneous model. Computational procedures of in flight ice accretion are considered. The results of numerical simulation of an ice growing on the cylinder and profile streamlined with two‐phase, viscous, compressible stream, taking into account the interaction of both carrier and liquid phases, the form of existence of moisture on a surface, the change of streamline body geometry and the influence of this change towards external stream are presented. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A New Method for the Assessment of Noise Pollution in Urban Agglomerations
Authors: Arghir Mariana , Macovescu Sorin Constantin 
Published: November 2013

AbstractThis work introduces a new method for the assessment of sound pollution in urban agglomeration. The method is based on fuzzy technique, which is a not used method until at this time for the pollution evaluation, but it will prove to be particularly useful and competitiveness. Starting from the classics design of the crowd and element of a crowd, shall be determined characteristics called degrees of belonging. The work presents the theoretical appropriateness for the application of fuzzy technique, the steps necessary to apply it, the program for the application of this technique, but also the computerized results obtained by application of the new methods, for the assessment of sound pollution by fuzzy technique. Concrete Implementation of a study from municipal area, with the implementation of the evaluation system based on fuzzy crowd is a rapid method, non‐invasive, and has been obtained from the indicator of the impact on an intense inhabited road and powerful intense polluted from the movement of motor vehicles. Results of the study obtained from the application of technique fuzzy, compared with the measurement results in the same places, have proved viable and thus fuzzy technique becomes a useful tool, quick and non ‐destructive test for the assessment noise pollution in urban agglomerations. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Model Identification for Flow Simulations in Geothermal Reservoirs: Towards Optimally Drilling Boreholes
Authors: Padalkina Kateryna , Bücker H. Martin , Herty Michael , Rath Volker , Seidler Ralf 
Published: November 2013

AbstractIn geothermal reservoir engineering, one is interested in determining the location of boreholes such that measurements taken therein, say temperature, will allow the estimation of unknown parameters such as porosity and permeability. We formulate such a particular borehole location problem and find its solution by techniques from optimal experimental design. More precisely, we minimize the D‐optimality criterion to find an optimal location of a single borehole to estimate hydraulic permeability from temperature measurements in two boreholes. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linearized Elasticity as Γ‐Limit of Finite Elasticity in the Case of Cracks
Authors: Gussmann Pascal 
Published: November 2013

AbstractThe small‐deformation limit of finite elasticity is considered in presence of a fixed crack. The rescaled finite energies with the constraint of global injectivity are shown to Γ‐converge to the linearized elastic energy with a local constraint of noninterpenetrability on the crack. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Uniqueness of Integrable Solutions ∇ζ = Gζ, ζ∣Γ = 0 for Integrable Tensor‐Coefficients G and Applications to Elasticity
Authors: Lankeit Johannes , Neff Patrizio , Pauly Dirk 
Published: November 2013

AbstractLet $\Omega\subset R^N$ be bounded Lipschitz and $\emptyset\neq\Gamma\subset \partial\Omega$ relatively open. We show that the solution to the linear first order system 1:

vanishes if $G \in {\rm L}^1(\Omega;{\rm I\!R}^{(N \times N)\times N})$ and $\zeta \in {\rm W}^{1,1}(\Omega;{\rm I\!R}^N)$, (e.g. $\zeta \in L^2, G \in L^2$). We prove

to be a norm if $P \in {\rm L}^\infty (\Omega;{\rm I\!R}^{3\times 3})$ with ${\rm Curl}\; P \in {\rm L}^p (\Omega;{\rm I\!R}^{3\times 3})$, ${\rm Curl}\; P^{-1} \in {\rm L}^q (\Omega;{\rm I\!R}^{3\times 3})$ for some p, q > 1 with 1/p + 1/q = 1 and ${\rm det}P \geq c^{+} > 0$. We give a new proof for the so called ‘in‐finitesimal rigid displacement lemma’ in curvilinear coordinates: Let $\Phi \in {\rm H}^1(\Omega;{\rm I\!R}^{3}), \Omega \in {\rm I\!R}^{3}$, satisfy ${\rm sym} (\nabla\Phi^{\rm T} \nabla\Psi) = 0$ for some $\Psi \in {\rm W}^{1,\infty} (\Omega;{\rm I\!R}^{3}) \cap {\rm H}^2 (\Omega;{\rm I\!R}^{3})$ with ${\rm det}\nabla\Psi \geq c^{+} > 0$. Then there are $a \in {\rm I\!R}^{3}$ and a constant skew‐symmetric matrix $A \in {\rm so}(3)$, such that $\Phi = A\Psi +a$. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Singular fractional differential equations
Authors: Stojanovic Mirjana 
Published: November 2013

AbstractFractional differential equations have received increasing attention during recent years since the behavior of many physical systems can be properly described using the fractional order system theory.By fractional analog for Duhamel principle we give the existence‐uniqueness result for linear and nonlinear time fractional evolution equations with singularities in corresponding norm in extended Colombeau algebra of generalized functions. In order to find the explicit solutions we use integral representation of the solution obtained via Laplace and Fourier transforms in succession and their inverses. We deal with some nonlinear models with singularities appearing in viscoelasticity and in anomalous processes, extending the results in viscoelasticity, continuum random walk, seismology, continuum mechanics and many other branches of life and science. The main task is finding existence‐uniqueness results like in the case of evolution equations with entire derivatives. By examining the fractional evolution equations it turns out that they lead to till now known results from the evolution equations with entire derivatives in limiting case. They give more, behavior of the solution when order of derivatives are inside the intervals of entire points. In this way we can follow the influence of the operators generated by entire derivative in many fractional time evolution PDEs especially with singular initial data, and non‐Lipschitz's nonlinear term.Apart from evolution equations we prove also an existence‐uniqueness result for an initial value problem with singularities for linear and nonlinear fractional elliptic equation of Helmholtz type and fractional order α, where 1 < Re(α) ≤ 2, with respect to the one variable from R+. As a framework, we employ also Colombeau algebra of generalized functions containing fractional derivatives and operations among them in order to deal with the fractional equations with singularities. We apply the same techniques to the fractional Laplace and Poisson equation linear and nonlinear ones. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Uncertainty Quantification and Non‐Linear Bayesian Update of PCE Coefficients
Authors: Litvinenko Alexander , Matthies Hermann G. 
Published: November 2013

AbstractThe Bayesian Update is quite vital for uncertainty quantification. With BU we can take into account the given measurements of our physical model and update the a priori probability density function (which is very often far away from the truth) of the uncertain parameter. The standard full BU is based on sampling and sampling is not always acceptable or possible. In addition, it can require a very large number of samples and is expensive. This led to the development of sampling‐free Bayesian updates. We derive it from the variational problem associated with conditional expectation. Whereas the linear BU is a linear function of the prediction mismatch, here we used higher order polynomials. As an example we took the chaotic Lorenz 84 model. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surf‐Riding Threshold of Ships in Random Seas
Authors: Dostal Leo , Kreuzer Edwin 
Published: November 2013

AbstractA possible stability failure in ship dynamics is surf‐riding of the ship in waves followed by broaching‐to. In order to exclude broaching one thus seeks to prevent the ship from surf‐riding. We analyze the surf‐riding problem of a ship in random seas as a weakly perturbed Hamiltonian system, where the excitation owing to irregular sea waves is modeled as a Gaussian process. Then, an approximation of the probability of surf‐riding in irregular sea waves is obtained using the stochastic Melnikov's method, by which means transitions from the asymmetric periodic surging motion to the surf‐riding equilibrium are identified. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Infinite‐Dimensional Semismooth Newton Method for Elasto‐Plastic Contact Problems
Authors: Hintermüller Michael , Rösel Simon 
Published: November 2013

AbstractA Fenchel dualization scheme for the one‐step time‐discretized elasto‐plastic contact problem with kinematic or isotropic hardening is considered. The associated path is induced by a combined Moreau‐Yosida / Tichonov regularization of the dual problem. The sequence of solutions to the regularized problems is shown to converge strongly to the solution of the original problem. This property relies on the density of the intersection of certain convex sets. The corresponding conditions are worked out and customary regularization approaches are shown to be valid in this context.It is also argued that without higher regularity assumptions on the data the resulting problems possess Newton differentiable optimality systems in infinite dimensions [2]. Consequently, each regularized subsystem can be solved mesh‐independently at a local superlinear rate of convergence [6]. Numerically the problems are solved using conforming finite elements. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sparse‐Grid Surrogate Models for Uncertainty Analysis
Authors: Walz Nico‐Philipp , Hanss Michael 
Published: November 2013

AbstractThe computation of fuzzy arithmetical solutions of problems involving uncertain, fuzzy‐valued model parameters can be formulated as a nested sequence of optimization problems. In order to reduce the amount of model evaluations, which is often a limiting factor for the applicability of uncertainty analysis if the original model is evaluated, a surrogate‐model approach based on sparse‐grid interpolation is investigated. The optimization process is then performed on the basis of the surrogate representation, leading to a significant improvement with respect to the computation time. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The extended Kalman Filter and the unscented Kalman Filter for Material Parameter Identification with Application in Tunneling
Authors: Nguyen Luan T. , Nestorović Tamara 
Published: November 2013

AbstractWe present in this work the use of the extended Kalman filter (EKF) and unscented Kalman filter (UKF) for identification of constitutive material parameters with application in mechanized tunneling. Although both filters are based on the principle of recursive least squares estimation, one differs from another in terms of where approximation is made. Whereas in the EKF first‐order Taylor series expansion is used to approximate the nonlinear modeling equation, in the UKF approximation of the probability density of the state is made using a small number of well defined points. To validate the methods, we performed parameter identification of the Hardening Soil constitutive model used for describing the soil behavior in an tunnel excavation model. Both methods showed fast and stable convergence of the considered soil parameters ‐ the four parameters of the Hardening Soil model. Although the EKF requires less number of forward calculations of the numerical model, the UKF is favored since it does not require calculation of the derivatives of the observables with respect to the identifying parameters. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inverse Design of a Displacement Body with a discrete Adjoint Method
Authors: Stapel Waldemar 
Published: November 2013

AbstractWind tunnel experiments at German Aerospace Center (DLR) for the analysis of laminar turbulent transition showed that a nearly linearly decreasing pressure distribution at a plate is able to suppress Tollmien‐Schlichting boundary layer instabilities. Nevertheless, this pressure distribution leads to the growth of nonlinear instabilities in cross flow direction. Within up‐ucoming research projects at DLR it is intended to further investigate this cross flow boundary layer instabilities. The experimental setup consists of a flat plate, a displacement body mounted above the plate and an additional supporting wing. The supporting wing prevents flow separations. The displacement body imposes the particular pressure distribution upon the upper side of the plate. However, contour and position of the displacement body is not known by detail. Therefore, the given pressure distribution is to be recreated by an inverse design procedure. The task can be seen as a design optimisation to a given pressure function. To provide a fast evaluation the discrete adjoint method of the TAU‐Code is used. The problem's cost function is regarded as the residual of the current and the target pressure. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A modified adaptive‐order rational Arnoldi method for model order reduction
Authors: Bodendiek André , Bollhöfer Matthias 
Published: November 2013

AbstractA Greedy‐type expansion point selection for moment‐matching methods in model order reduction mainly depends on the computation of a sequence of reduced order models. Typically, the adaptive‐order rational Arnoldi (AORA) method resembles an efficient way for the computation of a Galerkin projection corresponding to a set of expansion points. We will provide an extension of the AORA method, in order to reuse the orthonormal basis from previous calls of the AORA method. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bernstein Polynomial Collocation Method for Elliptic Boundary Value Problems
Authors: Mirkov Nikola , Rašuo Boško 
Published: November 2013

AbstractWe present a summary of recent developments in application of Bernstein polynomials to solution of elliptic boundary value problems with a pseudospectral method. Solution is approximated using Benstein polynomial interpolant defined at points of the extrema of Chebyshev polynomials i.e. the Chebyshev‐Gauss‐Lobatto (CGL) nodes. This approach brings impovement comparing to the Bernstein interpolation at equidistant nodes we used previously [1]. We show that this approach leads to spectral convergence and accuracy comparable to that of pseudospectral methods with orthogonal polynomials (Chebyshev, Legendre). The algorithm is implemented in open source librarybernstein‐poly, which is available online. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Modification of the Shishkin Discretization Mesh
Authors: Vulanović Relja , Teofanov Ljiljana 
Published: November 2013

AbstractIn this paper we consider a modification of the Shishkin discretization mesh designed for the numerical solution of one‐dimensional linear convection‐diffusion singularly perturbed problems. The modification consists of a slightly different choice of the transition point between the fine and coarse parts of the mesh. This leads to a better layer‐resolving mesh and to an improvement in the accuracy of the computed solution although the convergence order remains the same. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)