首页 | 综合通知 | 教务教学 | 学术交流 | 留学信息 | 科研管理 | 文献服务 | 招标信息 | 网络服务 
当前位置: 校园公告>>学术交流>>正文
【学术讲座】111引智基地系列讲座 —《Physics of Fluid》主编GIACOMIN(杰克明)教授学术报告会
2018-09-04 11:20   航空学院 审核人:   (点击: )

报告人:《Physics of Fluid》主编GIACOMIN(杰克明)教授

邀请人:郗恒东教授

主办单位:飞行器复杂流动与控制学科创新引智基地

时间:9月7日(星期五)9:00-11:30

地点:航空楼A706

 

时间:9:00-10:00

报告题目:The New Physics of Fluids

报告摘要:

Professor Giacomin has led Physics of Fluids as its Editor-in-Chief since 2016. This lecture is designed to interest authors, new and old. It tells the story of the journal’s surging success, with special focus on growth from China.

 

时间:10:30-11:30

报告题目:Exploiting Large-Amplitude Oscillatory Shear Flow

报告摘要:

Large-amplitude oscillatory shear flow (LAOS) is the most popular laboratory experiment for investigating the nonlinear rheological behavior of polymeric liquids (see Fig. 1). This nonlinear experiment brings out distortion in the stress response. Attempts to analyze this distortion using continuum approaches have lead us to quantitative responses but these teach us little about the molecular origins of the distortions, namely molecular structure and orientation. Here, we investigate stress responses from LAOS from continuum and molecular approaches. We also explore traverse the bridge between these two approaches, which we callmacromolecular continua.

In the continuum framework, the Oldroyd 8-constant framework2is a versatile set of popular fluid models3. Moreover, when generalized to multimode fluid using the Spriggs relations, this fluid model can successfully predict nonlinear behaviour of polymeric liquids. Finally, the Oldroyd 8-constant framework yields exact solutions, for both shear stress and normal stress difference responses. Whereas these exact solutions give us general idea on how material reacts to nonlinear input, using them can be cumbersome. We can exploit these exact solutions to get simpler forms called Padé approximants. Under some circumstances, the best of these, for either the shear stress or the normal stress differences, gives the same level of accuracy as the exact expression. Lastly, we can also exploit these exact solutions for the thermodynamic analysis of flow stability to depict when LAOS is unstable (see Fig. 2).

Molecular structure and orientation are the primary causes of nonlinearity in viscoelastic behaviors of polymeric liquids. To explain the molecular origins of polymer fluid elasticity, we find the rigid dumbbell suspension to be the simplest relevant. By relevant we at least mean, predicting distortion in the stress responses. The stress expressions for molecular models take the approximate form of truncated power series. We can thus exploit the best Padé approximants to perfect these truncated expansions. Since arriving at these truncated expansions involves difficulty, perfecting these so easily is useful.

Figure. 1.Rigid dumbbells in LAOS in Cartesian coordinates.

Figure 2.Ziegler instability corotational Maxwell fluid in LAOS and over Pipkin space.

References

1.T-T. Tee, and J.M. Dealy,Trans. Soc. Rheol.,19, 595 (1975);T.-T. Tee,Large amplitude oscillatory shearing of polymer melts, Ph.D. Thesis, Chem. Eng. Dept., McGill University, Montreal, Canada, 1974

2. J.G. Oldroyd,Proc. Royal Soc. A,245, 278 (1958).

3. C. Saengow, A.J. Giacomin, and C. Kolitawong,Physics of Fluids,29(4), 043101 (2017).

关闭窗口
最新公告
材料学院陕西省材料分析研究中心关于...
驻校艺术家计划——学生书画作品展及...
【通知公告】Haiyan Su副教授 “Stati...
关于学习贯彻《新时代高校教师职业行...
关于申报“2019年度西北工业大学在华...
驻校艺术家计划《书画名家工作坊》开...
国家审计走进西北工业大学 财经法治...
关于高雅艺术进校园——国家京剧院赴...
【会议通知】2018年仿真学术交流会
西北工业大学2018迎新文艺晚会预告
西工大主页  招聘信息  就业信息  本科招生  研招信息
版权所有©西北工业大学  地址:西安市友谊西路127号 邮编:710072