14th WCCM-ECCOMAS Congress最新文献

Energy Preserving Multiphase Flows: Application to Falling Films 保能多相流:在降膜中的应用

14th WCCM-ECCOMAS Congress Pub Date : 2021-10-07 DOI: 10.23967/WCCM-ECCOMAS.2020.133

N. Valle, F. Trias, J. Castro

引用次数: 1

On the Quantification of Discretization Uncertainty: Comparison of Two Paradigms 关于离散化不确定性的量化:两种范式的比较

14th WCCM-ECCOMAS Congress Pub Date : 2021-03-25 DOI: 10.23967/wccm-eccomas.2020.260

J. Bect, S. Zio, G. Perrin, C. Cannamela, E. Vázquez

{"title":"On the Quantification of Discretization Uncertainty: Comparison of Two Paradigms","authors":"J. Bect, S. Zio, G. Perrin, C. Cannamela, E. Vázquez","doi":"10.23967/wccm-eccomas.2020.260","DOIUrl":"https://doi.org/10.23967/wccm-eccomas.2020.260","url":null,"abstract":"Numerical models based on partial differential equations (PDE), or integro-differential equations, are ubiquitous in engineering and science, making it possible to understand or design systems for which physical experiments would be expensive-sometimes impossible-to carry out. Such models usually construct an approximate solution of the underlying continuous equations, using discretization methods such as finite differences or the finite elements method. The resulting discretization error introduces a form of uncertainty on the exact but unknown value of any quantity of interest (QoI), which affects the predictions of the numerical model alongside other sources of uncertainty such as parametric uncertainty or model inadequacy. The present article deals with the quantification of this discretization uncertainty.A first approach to this problem, now standard in the V&V (Verification and Validation) literature, uses the grid convergence index (GCI) originally proposed by P. Roache in the field of computational fluid dynamics (CFD), which is based on the Richardson extrapolation technique. Another approach, based on Bayesian inference with Gaussian process models, was more recently introduced in the statistical literature. In this work we present and compare these two paradigms for the quantification of discretization uncertainty, which have been developped in different scientific communities, and assess the potential of the-younger-Bayesian approach to provide a replacement for the well-established GCI-based approach, with better probabilistic foundations. The methods are illustrated and evaluated on two standard test cases from the literature (lid-driven cavity and Timoshenko beam).","PeriodicalId":148883,"journal":{"name":"14th WCCM-ECCOMAS Congress","volume":"146 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115474007","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

Multiphysics Modelling of a Hybrid Rocket Engine 混合动力火箭发动机的多物理场建模

14th WCCM-ECCOMAS Congress Pub Date : 2021-03-12 DOI: 10.23967/WCCM-ECCOMAS.2020.213

A. Ferrero, F. Masseni, L. Muscarà, D. Pastrone

{"title":"Multiphysics Modelling of a Hybrid Rocket Engine","authors":"A. Ferrero, F. Masseni, L. Muscarà, D. Pastrone","doi":"10.23967/WCCM-ECCOMAS.2020.213","DOIUrl":"https://doi.org/10.23967/WCCM-ECCOMAS.2020.213","url":null,"abstract":"Hybrid rocket engines (HREs) present interesting advantages over liquid rocket engines (LREs) and solid rocket motors (SRMs). In order to appreciate these advantages, one should look into the different combustion characteristics; in the hybrid engines the combustion occurs in a macrodiffusion flame and the oxidizer to fuel ratio changes along the combustion chamber. In solid rockets the oxidizer and fuel are mechanically or chemically bound in a single solid phase and they burn with a microdiffusion flame while, in the liquid engines, the combustion results from a premixed flame. Thus, unlike hybrids, both these engines have an uniform mixture ratio. On the other hand, in hybrid engines it is possible to throttle by modulating only the liquid flow rate, which is simpler than in a liquid engine where two flow rates must be synchronized. Furthermore, the European Union is pushing to proscribe some dangerous liquid propellants such as the hydrazine derivatives. As a consequence, there is a huge interest for the “green” propellants and also in this case the HREs present an optimum choice since they employ low toxicity propellants. Indeed, most hybrid propellants and additives are essentially nontoxic, resulting in minimal local environmental impact. The physical separation of fuel and oxidizer serves also to reduce the probability of an accident, which could lead to propellant release in the environment. An interesting feature is that the HREs seem viable for the lift-off from Mars because the typical solid fuels employed in HREs, contrary from the ones used for SRMs, do not develop cracks when subjected to wide temperature ranges [1]. From an economical point of view the operational cost for hybrid systems is affordable thanks to their safety features and inert propellant [2]. Despite the several advantages of hybrid systems compared to liquid and solid systems, the hybrids have not seen yet a mass production unlike heritage propulsion systems. In fact, the","PeriodicalId":148883,"journal":{"name":"14th WCCM-ECCOMAS Congress","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130424520","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: 0

Energy-Momentum Scheme For Nonlinear Thermo-Electro-Elastodynamics 非线性热电弹性动力学的能量-动量格式

14th WCCM-ECCOMAS Congress Pub Date : 2021-03-11 DOI: 10.23967/WCCM-ECCOMAS.2020.134

M. Franke, R. Ortigosa, Amparo Gil, M. Hille

引用次数: 0

Three-Dimensional Direct Numerical Simulation (DNS) of Taylor Bubbles Rising in Non-Newtonian Environments 非牛顿环境中泰勒气泡上升的三维直接数值模拟

14th WCCM-ECCOMAS Congress Pub Date : 2021-03-11 DOI: 10.23967/WCCM-ECCOMAS.2020.343

A. Amani, J. Castro, A. Oliva

引用次数: 0

Cad-Based Adaptive Shape Parametrisation for Aerodynamic Shape Optimisation 基于cad的气动外形优化自适应参数化

14th WCCM-ECCOMAS Congress Pub Date : 2021-03-11 DOI: 10.23967/WCCM-ECCOMAS.2020.079

R. Jesudasan, J. Mueller

{"title":"Cad-Based Adaptive Shape Parametrisation for Aerodynamic Shape Optimisation","authors":"R. Jesudasan, J. Mueller","doi":"10.23967/WCCM-ECCOMAS.2020.079","DOIUrl":"https://doi.org/10.23967/WCCM-ECCOMAS.2020.079","url":null,"abstract":". Non-Uniform Rational B-Splines (NURBS) have become the industrial standard to represent and exchange a CAD geometry between CAD/CAE systems. CAD-based shape parameterisation uses parameters of a CAD model to modify the shape which allows to integrate a CAD model into the design loop. However, feature-trees of typical commercial CAD systems are not open and obtaining exact derivatives for gradient-based optimisation methods is not possible. Using the CAD-based NSPCC approach a designer can deform multiple NURBS patches in the design loop without violating geometric and/or thickness constraints. The NSPCC approach takes CAD descriptions as input and perturbs the control points of the NURBS boundary representation to modify the shape. In this work, an adaptive NSPCC method is proposed where the optimisation begins with a coarser design space and adapts to ﬁner parametrisation during the design process where more shape control is needed. The reﬁnement sensor is based on a comparison of smoothed node-based sensitivity compared to its projection onto the shape modes of the current parametrisation. Both static and adaptive parametrisation methods are coupled in the adjoint-based shape optimisation process to reduce the total pressure loss of a turbine blade internal cooling channel. The discrete adjoint ﬂow solver STAMPS is used to compute the ﬂow ﬁelds and their derivatives w.r.t. surface node displacements. The shape derivatives for gradient-based optimisation are obtained by application of reverse mode AD to the NSPCC","PeriodicalId":148883,"journal":{"name":"14th WCCM-ECCOMAS Congress","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129053818","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: 0

Modified Spectral Method of Anisotropic Turbulent Velocity Field Generation Preserving Incompressibility 保持不可压缩性的各向异性湍流速度场生成的修正谱法

14th WCCM-ECCOMAS Congress Pub Date : 2021-03-11 DOI: 10.23967/WCCM-ECCOMAS.2020.066

A. V. Alexandrov, L. Dorodnicyn, A. Duben, D. Kolyukhin

引用次数: 0

An Adjoint Method for the Optimal Boundary Control of Turbulent Flows Modeled with the Rans System 用Rans系统建模的湍流最优边界控制的伴随方法

14th WCCM-ECCOMAS Congress Pub Date : 2021-03-11 DOI: 10.23967/WCCM-ECCOMAS.2020.055

A. Chierici, L. Chirco, V. Giovacchini, S. Manservisi

引用次数: 0

Reversible Order-Disorder Transition in Ettringite-Metaettringite Conversion 钙矾石-偏钙矾石转换中的可逆有序-无序转变

14th WCCM-ECCOMAS Congress Pub Date : 2021-03-11 DOI: 10.23967/WCCM-ECCOMAS.2020.289

Tulio Honoro, S. A. Dandachli, Alexandra Bourdot

{"title":"Reversible Order-Disorder Transition in Ettringite-Metaettringite Conversion","authors":"Tulio Honoro, S. A. Dandachli, Alexandra Bourdot","doi":"10.23967/WCCM-ECCOMAS.2020.289","DOIUrl":"https://doi.org/10.23967/WCCM-ECCOMAS.2020.289","url":null,"abstract":". The stability of ettringite under sorption and the conversion into metaettringite are studied using hybrid Grand Canonical Monte Carlo (GCMC) and (classical) Molecular Dynamics (MD) simulations sampling the osmotic ensemble. The desorption branch obtained from simulation and the associated volume changes are in agreement with the experimental evidence. We pay special attention to the structural changes at low RH, which is associated with metaettringite conversion, which is recognized as a disordered polymorph of ettringite with an unknown structure to date. We show that the conversion of ettringite into metaettringite is associated with an increase in entropy. The adsorption branch obtained from simulations is reversible in the ettringite domain in agreement with experiments. The reversibility in the conversion of metaettringite into ettringite, which is observed experimentally, is not captured by the simulation approach adopted. The large deformations associated with ettringite desorption make it difﬁcult to capture reversibility with a direct sampling of the osmotic ensemble. Further, we discuss the role of hydrogen bonds on the hysteresis observed in sorption cycles in ettringite.","PeriodicalId":148883,"journal":{"name":"14th WCCM-ECCOMAS Congress","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127803662","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: 0

Numerical Investigation of Oleo-Pneumatic Shock Absorber: Setup and Validation 油压-气动减振器的数值研究:建立与验证

14th WCCM-ECCOMAS Congress Pub Date : 2021-03-11 DOI: 10.23967/WCCM-ECCOMAS.2020.231

A. A. Al-Shabab, D. Vitlaris, Zhonglu Lin, B. Grenko, Panagiotis Tsoutsanis, A. Antoniadis, M. Skote

引用次数: 0