Theoretical and Applied Mechanics最新文献_第8页

Estimation of wind turbine blade aerodynamic performances computed using different numerical approaches 用不同数值方法计算风力机叶片气动性能的估计

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Theoretical and Applied Mechanics Pub Date : 2018-01-01 DOI: 10.2298/tam171130004s

J. Svorcan, Ognjen Peković, Toni Ivanov

{"title":"Estimation of wind turbine blade aerodynamic performances computed using different numerical approaches","authors":"J. Svorcan, Ognjen Peković, Toni Ivanov","doi":"10.2298/tam171130004s","DOIUrl":"https://doi.org/10.2298/tam171130004s","url":null,"abstract":". Although much employed, wind energy systems still present an open, contemporary topic of many research studies. Special attention is given to precise aerodynamic modeling performed in the beginning since overall wind turbine performances directly depend on blade aerodynamic performances. Several models different in complexity and computational requirements are still widely used. Most common numerical approaches include: i) momentum balance models, ii) potential flow methods and iii) full computational fluid dynamics solutions. Short explanations, reviews and comparison of the existing computational concepts are presented in the paper. Simpler models are described and im- plemented while numerous numerical investigations of isolated horizontal-axis wind turbine rotor consisting of three blades have also been performed in ANSYS FLUENT 16.2. Flow field is modeled by Reynolds Averaged Navier– Stokes (RANS) equations closed by two different turbulence models. Results including global parameters such as thrust and power coefficients as well as local distributions along the blade obtained by different models are compared to available experimental data. Presented results include fluid flow visualizations in the form of velocity contours, sectional pressure distributions and values of power and thrust force coefficients for a range of operational regimes. Although obtained numerical results vary in accuracy, all presented numerical settings seem to slightly under- or over-estimate the global wind turbine parameters (power and thrust force coefficients). Turbulence can greatly affect the wind turbine aerodynamics and should be modeled with care.","PeriodicalId":44059,"journal":{"name":"Theoretical and Applied Mechanics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86658724","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: 4

On a property of differential equations integrable using meromorphic double-periodic functions 用亚纯双周期函数研究微分方程可积的性质

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Theoretical and Applied Mechanics Pub Date : 2018-01-01 DOI: 10.2298/TAM1801121P

M. Petrovitch

引用次数: 2

Analysis of dynamics variation against thixotropic parameter’s preferential range 触变参数优先范围的动力学变化分析

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Theoretical and Applied Mechanics Pub Date : 2018-01-01 DOI: 10.2298/TAM180819013S

N. Shahid

引用次数: 0

Some sigmoid and reverse-sigmoid response patterns emerging from high-power loading of solids 高功率固体载荷下出现的一些s型和反s型响应模式

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Theoretical and Applied Mechanics Pub Date : 2018-01-01 DOI: 10.2298/TAM171203007M

S. Mastilovic

{"title":"Some sigmoid and reverse-sigmoid response patterns emerging from high-power loading of solids","authors":"S. Mastilovic","doi":"10.2298/TAM171203007M","DOIUrl":"https://doi.org/10.2298/TAM171203007M","url":null,"abstract":". The objective of the present review is twofold. First, it aims at highlighting some sigmoid and reverse-sigmoid response patterns observed re- cently in the course of simulations of the high-strain-rate loading of (mostly, quasibrittle) solids. Second, it aims at reviewing various properties of two models used frequently as curve fitting tools for nonlinear and saturable phenomena. These two models-inspired by the Hill and the Weibull cumula- tive distribution functions-are bounded by two horizontal asymptotes with a smooth transition between the baseline and the final saturation state, char- acterized by a non-negative (a non-positive) derivative at each point for the sigmoid (the reverse-sigmoid) shape. Although they were used primarily for data fitting because of their flexibility and effectiveness, these nonlinear models possess other properties useful for the analysis of the irreversible, nonlinear and far-from-equilibrium phenomena. The main features of these two models are systematically examined in this review. In spite of the fact that satis- factory curve-fitting of data could not be considered a proof of causality it could underline a pattern of behavior and, perhaps, provide an investigation guidance.","PeriodicalId":44059,"journal":{"name":"Theoretical and Applied Mechanics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78267797","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: 3

Mathematical analysis of hydrodynamics and tissue deformation inside an isolated solid tumor 孤立实体瘤内流体力学和组织变形的数学分析

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Theoretical and Applied Mechanics Pub Date : 2018-01-01 DOI: 10.2298/TAM180810014A

Meraj Alam, Bibaswan Dey, G. Raja

{"title":"Mathematical analysis of hydrodynamics and tissue deformation inside an isolated solid tumor","authors":"Meraj Alam, Bibaswan Dey, G. Raja","doi":"10.2298/TAM180810014A","DOIUrl":"https://doi.org/10.2298/TAM180810014A","url":null,"abstract":"In this article, we present a biphasic mixture theory based mathematical model for the hydrodynamics of interstitial fluid motion and mechanical behavior of the solid phase inside a solid tumor. The tumor tissue considered here is an isolated deformable biological medium. The solid phase of the tumor is constituted by vasculature, tumor cells, and extracellular matrix, which are wet by a physiological extracellular fluid. Since the tumor is deformable in nature, the mass and momentum equations for both the phases are presented. The momentum equations are coupled due to the interaction (or drag) force term. These governing equations reduce to a one-way coupled system under the assumption of infinitesimal deformation of the solid phase. The well-posedness of this model is shown in the weak sense by using the inf-sup (Babuska–Brezzi) condition and Lax–Milgram theorem in 2D and 3D. Further, we discuss a one-dimensional spherical symmetry model and present some results on the stress fields and energy of the system based on L2 and Sobolev norms. We discuss the so-called phenomena of “necrosis” inside a solid tumor using the energy of the system.","PeriodicalId":44059,"journal":{"name":"Theoretical and Applied Mechanics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86048800","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: 3

Effects of small boundary perturbation on the MHD duct flow 小边界扰动对MHD管道流动的影响

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Theoretical and Applied Mechanics Pub Date : 2017-07-02 DOI: 10.2298/TAM170511004M

U. Mahabaleshwar, Igor Pažanin, M. Radulović, F. S. Grau

引用次数: 6

Extended Lagrangian formalism for rheonomic systems with variable mass 变质量流变系统的扩展拉格朗日形式

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Theoretical and Applied Mechanics Pub Date : 2017-01-01 DOI: 10.2298/TAM170601006M

D. Mušicki

{"title":"Extended Lagrangian formalism for rheonomic systems with variable mass","authors":"D. Mušicki","doi":"10.2298/TAM170601006M","DOIUrl":"https://doi.org/10.2298/TAM170601006M","url":null,"abstract":"In this paper the extended Lagrangian formalism for the rheonomic systems (Dj. Mušicki, 2004), which began with the modification of the mechanics of such systems (V. Vujičić, 1987), is extended to the systems with variable mass, with emphasis on the corresponding energy relations. This extended Lagrangian formalism is based on the extension of the set of chosen generalized coordinates by new quantities, suggested by the form of nonstationary constraints, which determine the position of the frame of reference in respect to which these generalized coordinates refer. As a consequence, an extended system of the Lagrangian equations is formulated, accommodated to the variability of the masses of particles, where the additional ones correspond to the additional generalized coordinates. By means of these equations, the energy relations of such systems have been studied, where it is demonstrated that here there are four types of energy conservation laws. The obtained energy laws are more complete and natural than the corresponding ones in the usual Lagrangian formulation for such systems. It is demonstrated that the obtained energy laws, are in full accordance with the energy laws in the corresponding vector formulation, if they are expressed in terms of the quantities introduced in this formulation of mechanics. The obtained results are illustrated by an example: the motion of a rocket, which ejects the gasses backwards, while this rocket moves up a straight line on an oblique plane, which glides uniformly in a horizontal direction.","PeriodicalId":44059,"journal":{"name":"Theoretical and Applied Mechanics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77738670","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: 2

A theory of strain-gradient plasticity with effect of internal microforce 考虑内力影响的应变梯度塑性理论

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Theoretical and Applied Mechanics Pub Date : 2017-01-01 DOI: 10.2298/TAM160312010B

A. Borokinni, A. Akinola, O. Layeni

{"title":"A theory of strain-gradient plasticity with effect of internal microforce","authors":"A. Borokinni, A. Akinola, O. Layeni","doi":"10.2298/TAM160312010B","DOIUrl":"https://doi.org/10.2298/TAM160312010B","url":null,"abstract":"This paper develops a theory of strain gradient plasticity for isotropic bodies undergoing small deformation in the absence of plastic spin. The proposed theory is based on a system of microstresses which include a microstress vector consistent with microforce balance; the mechanical form of the second law of thermodynamics which includes work performed by the microstresses during plastic flow; and a constitutive theory that allows the free energy to depend on the elastic strain Ee, divergence of plastic strain divEp and the Burgers tensor G. Substitution of the constitutive relations into the microforce balance leads to a nonlinear partial differential equation in the plastic strain known as flow rule which captures the presence of an additional energetic length scale arising from the accounting of microstress vector. In addition to the flow rule, nonstandard boundary conditions are obtained, and as an aid to finite element solution a variational formulation of the flow rule is deduced. Finite element solution is obtained of one-dimensional problem of viscoplastic simple shearing under gravity force, where it is shown that for a fixed dissipative length scale, increase in the energetic length scales will result in decrease in the plastic strain.","PeriodicalId":44059,"journal":{"name":"Theoretical and Applied Mechanics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90218923","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: 3

The brachistochronic motion of a vertical disk rolling on a horizontal plane without slip 无滑移的垂直圆盘在水平面上滚动的腕部慢性运动

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Theoretical and Applied Mechanics Pub Date : 2017-01-01 DOI: 10.2298/tam171002015o

A. Obradović, S. Šalinić, R. Radulović

引用次数: 5

On damage tensor in linear anisotropic elasticity 线性各向异性弹性中的损伤张量

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Theoretical and Applied Mechanics Pub Date : 2017-01-01 DOI: 10.2298/TAM170306018J

J. Jarić, D. Kuzmanović

引用次数: 1