Communications in Numerical Methods in Engineering最新文献_第2页

Diffuse interface method for simulation of the chemical vapor deposition of pyrolytic carbon: Aspects of the mathematical formulation 模拟热解碳化学气相沉积的扩散界面法:数学公式的几个方面

Communications in Numerical Methods in Engineering Pub Date : 2008-12-01 DOI: 10.1002/CNM.1083

S. Dimitrov, Alexander Ekhlakov, T. Langhoff

{"title":"Diffuse interface method for simulation of the chemical vapor deposition of pyrolytic carbon: Aspects of the mathematical formulation","authors":"S. Dimitrov, Alexander Ekhlakov, T. Langhoff","doi":"10.1002/CNM.1083","DOIUrl":"https://doi.org/10.1002/CNM.1083","url":null,"abstract":"The present work is inspired by Anderson et al. (Phys. D Nonlinear Phenom. 2000; 135(1¯2):175¯194) and Noll (http://www.math.cmu.edu/wn0g/noll) and falls in the conceptual line of the Ginzburg-Landau class of first-order phase-transition models based on the concept of phase-field parameter. Trying to keep the exposition as much general as possible, we develop below a thermodynamically consistent rationalization of the physical process of (anisotropic) deposition of pyrolytic carbon from a gas phase. The derivation line we follow is well established in the field of the modern continuum physics. From the covariance of the first principle of thermodynamics, the second Newton's law and the Liouville's theorem with respect to the one-dimensional Lie groups of transformations, the balance laws for the temperature, linear momentum and density are formulated. This system of partial differential equations is comprehended further by the constitutive laws for the phase field, the stress, and the heat and entropy fluxes obtained in a form consistent with the Clausius-Duhem understanding of the second law. The result referred to as a local, strongly coupled initial boundary value problem of chemical vapor deposition (IBVP-CVD) constitutes the general mathematical description of the CVD process. The weak form of isotropic IBVP-CVD is then derived and discretized by means of the discontinuous Galerkin method. At the end of the paper, we also derive the weak formulations for the local lifting operators that provide the stabilization mechanism for the discontinuous Galerkin discretization scheme.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1083","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51533886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Thermal and mechanical numerical modelling of electric discharge machining process 电火花加工过程的热力学数值模拟

Communications in Numerical Methods in Engineering Pub Date : 2008-12-01 DOI: 10.1002/CNM.1091

N. B. Salah, Farhat Ghanem, K. B. Atig

引用次数: 28

The effects of variable fluid properties and magnetic field on the flow of non‐Newtonian fluid film on an unsteady stretching sheet through a porous medium 变流体性质和磁场对非定常拉伸片上非牛顿流体膜在多孔介质中流动的影响

Communications in Numerical Methods in Engineering Pub Date : 2008-12-01 DOI: 10.1002/CNM.1099

N. S. Elgazery, M. Hassan

{"title":"The effects of variable fluid properties and magnetic field on the flow of non‐Newtonian fluid film on an unsteady stretching sheet through a porous medium","authors":"N. S. Elgazery, M. Hassan","doi":"10.1002/CNM.1099","DOIUrl":"https://doi.org/10.1002/CNM.1099","url":null,"abstract":"The effects of variable viscosity, variable thermal diffusivity and magnetic field on the flow and heat transfer in a laminar liquid film of non-Newtonian fluid on a horizontal stretching sheet through a porous medium are analyzed. Using a similarity transformation, the governing time-dependent boundary-layer equations for momentum and thermal energy are reduced to a set of coupled nonlinear ordinary differential equations. The resulting seven-parameter problem is solved numerically by using Chebyshev pseudospectral method for some representative value of the parameters. The numerical results show that variable viscosity, variable thermal diffusivity, the upper limit of apparent viscosity according to biviscosity model, the unsteadiness parameter, the magnetic parameter, and the permeability parameter have significant influences on the velocity and temperature profiles, shear stress, and Nusselt number. \u0000 \u0000 \u0000 \u0000It is observed that the presence as well as the increase in the unsteadiness parameter S, variable viscosity parameter β1, the upper limit of apparent viscosity β, and the magnetic parameter M lead to decrease in the fluid film thickness η∞. Also, as film thickness approaches zero as S comes close to the critical value; then, there is no available solution for the problem. The velocity profiles supported this result, since close to this critical value the velocity of the fluid vanishes. Copyright © 2008 John Wiley & Sons, Ltd.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1099","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51535503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 20

Numerical performance of compact fourth‐order formulation of the Navier–Stokes equations Navier-Stokes方程紧致四阶公式的数值性能

Communications in Numerical Methods in Engineering Pub Date : 2008-12-01 DOI: 10.1002/cnm.1090

E. Erturk

引用次数: 6

On decoupled time step/subcycling and iteration strategies for multiphysics problems 多物理场问题的解耦时间步长/子循环和迭代策略

Communications in Numerical Methods in Engineering Pub Date : 2008-12-01 DOI: 10.1002/CNM.1085

A. Valli, G. Carey, A. Coutinho

引用次数: 15

The mechanical response of Achilles tendon during different kinds of sports 不同运动形式下跟腱的力学反应

Communications in Numerical Methods in Engineering Pub Date : 2008-12-01 DOI: 10.1002/CNM.1096

Y. Gu, J. S. Li, M. Lake, X. Ren, Yanjun Zeng

引用次数: 7

Numerical studies of the influence of textural gradients on the local stress concentrations around fibers in carbon/carbon composites 织构梯度对碳/碳复合材料纤维周围局部应力集中影响的数值研究

Communications in Numerical Methods in Engineering Pub Date : 2008-02-07 DOI: 10.1002/CNM.1081

R. Piat, I. Tsukrov, T. Böhlke, Norbert Bronzel, Tilottama Shrinivasa, B. Reznik, D. Gerthsen

{"title":"Numerical studies of the influence of textural gradients on the local stress concentrations around fibers in carbon/carbon composites","authors":"R. Piat, I. Tsukrov, T. Böhlke, Norbert Bronzel, Tilottama Shrinivasa, B. Reznik, D. Gerthsen","doi":"10.1002/CNM.1081","DOIUrl":"https://doi.org/10.1002/CNM.1081","url":null,"abstract":"SUMMARY Carbon/carbon composites produced by chemical vapor infiltration consist of carbon fibers embedded in a matrix of pyrolytic carbon with anisotropic mechanical properties. The matrix around fibers consists of cylindrically shaped pyrolytic carbon layers of coating, which may have different textures with different mechanical properties in the axial, radial and circumferential directions. The goal of the present numerical study is to investigate the influence of the coating microstructure on stress concentrations and possible modes of failure in the carbon composite. Numerical modeling was performed on two length scales. First, the material properties of the differently textured pyrolytic carbon layers were determined on the nanometer scale using methodology based on the Eshelby theory for continuously distributed inclusions. Then, the obtained material parameters for each layer were used as input for the finite element models on the micrometer scale. The numerical simulations were conducted for three basic loading scenarios: uniaxial tension, shear loading and hydrostatic compression. The calculated stress distributions show zones of maximum stress concentrations and provide information on the possible failure regions for each material under all considered loading cases. The numerical results demonstrate good correspondence with experimentally identified failure regions. Copyright q 2008 John Wiley & Sons, Ltd.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1081","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51533811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Phase-field model for deposition of pyrolytic carbon 热解碳沉积的相场模型

Communications in Numerical Methods in Engineering Pub Date : 2008-01-24 DOI: 10.1002/CNM.1082

Alexander Ekhlakov, S. Dimitrov, T. Langhoff, E. Schnack

引用次数: 6

An explicit drive algorithm for aiding the design of firing sequence in side-drive micromotor 一种辅助侧驱式微马达发射顺序设计的显式驱动算法

Communications in Numerical Methods in Engineering Pub Date : 2008-01-24 DOI: 10.1002/CNM.1100

William K. S. Pao, W. Wong, A. Lai

引用次数: 4

Second-order explicit integrator via composition for coupled rotating rigid bodies applied to roller cone drill bits 应用于牙轮钻头的耦合旋转刚体二阶显式积分法

Communications in Numerical Methods in Engineering Pub Date : 2007-12-27 DOI: 10.1002/CNM.1079

L. Endres, P. Krysl

{"title":"Second-order explicit integrator via composition for coupled rotating rigid bodies applied to roller cone drill bits","authors":"L. Endres, P. Krysl","doi":"10.1002/CNM.1079","DOIUrl":"https://doi.org/10.1002/CNM.1079","url":null,"abstract":"We present a derivation of the equations of motion of a roller cone bit as an example of coupled rotating rigid bodies and apply a state-of-the-art numerical integrator to produce an algorithm for use in a bit dynamics software application. The equations are derived using the virtual power method, which naturally handles the constraint between the bit body and the cones. These equations are fully three-dimensional (three degrees of freedom for the body, plus one degree of freedom for each cone) and nicely parallel to the equations of motion of a single rigid body. We apply the composition of adjoint first-order integrators (reminiscent of the approach used earlier to derive an explicit midpoint Lie method (Int. J. Numer. Meth. Eng. 2005; 63:2171–2193) to produce an algorithm that maintains the properties of the original three degree-of-freedom integrator: second-order convergence, symplecticness, remarkable accuracy, and momentum conservation. This algorithm can be applied to other applications where one or more rigid bodies with a single rotational degree of freedom are attached to another rotating rigid body. Copyright © 2007 John Wiley & Sons, Ltd.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1079","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51534108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1