In the present paper, weakly enforced no-slip wall boundary conditions are revisited in the context of Large-Eddy Simulations (LES) with near-wall modeling. A new formulation is proposed in the framework of weakly enforced no-slip conditions that is better aligned with traditional near-wall modeling approaches than its predecessors. The new formulation is tested on turbulent open-channel flows at friction-velocity-based Reynolds numbers _Reτ=395Reτ=395 and 950 benchmark problems.

Seamless and minimally invasive three-dimensional interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating the syringe injection (and subsequent unfolding) of sub-micrometre-thick, centimetre-scale macroporous mesh electronics through needles with a diameter as small as 100 μm.

Most of the auxetic materials that have been characterized experimentally or studied analytically are anisotropic and this limits their possible applications, as they need to be carefully oriented during operation. Here, through a combined numerical and experimental approach, we demonstrate that 2D auxetic materials with isotropic response can be easily realized by perforating a sheet with elongated cuts arranged to form a periodic pattern with either six-fold or three-fold symmetry.

Recently we published a paper in Physical Review Applied. It can be downloaded from the link

 http://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.3.064014

 Abstract of the article is below:

Reconfigurable metamaterials -- putting the holes in the right place

Shu Yang¹ and Jie Yin²

¹Department of Materials Science and Engineering, University of Pennsylvania, E-mail: shuyang [at] seas.upenn.edu (shuyang[at]seas[dot]upenn[dot]edu)

The Computational Mechanics group at The University of Iowa, led by Professor S. Rahman, is looking for new Ph.D. students, who are capable of and interested in performing high-quality research on engineering design. The research, supported by National Science Foundation and others, entails building a solid mathematical foundation, devising efficient numerical algorithms, and developing practical computational tools for stochastic design optimization. A substantial background in solid mechanics and structural optimization is a must; exposures to stochastics and probabilistic methods are highly desirable.

If you are interested in pursuing a Ph.D. degree at Iowa, please contact and send a resume to: Professor Sharif Rahman at sharif-rahman [at] uiowa.edu. Please note that we are interested in students who already have M.S. degrees in engineering or mathematics. The desired start date is Spring 2016 or sooner.

Recently we published a paper in Composite Structures. It can be freely downloaded from the link

http://authors.elsevier.com/a/1RGr0x-7hNgCX

Abstract of the article is below:

Development of advanced materials for high-end applications is driven by the increasing understanding of the dynamics and properties of defect microstructures, leading to the ability to synthesize and control materials microstructures to meet specific application demands. Dislocation motion is the fundamental physical mechanism of the plastic deformation process in crystalline materials.

Special Issue on 

Nanoscale Biological Materials 

Call for Papers

与中国一起走向世界，与世界一起走向未来

锁志刚

西安交通大学毕业典礼，2015.6.27

尊敬的张迈曾书记，尊敬的王树国校长，

各位嘉宾，各位老师，各位同学，各位家长，

大家上午好！

感谢学校让我作为校友在毕业典礼上致辞。年轻的同学们，我想和你们谈一个大家都关心的话题：机会。

三十年前，也就是一九八五年，我从西安交通大学本科毕业。毕业典礼上，汪应洛副校长讲话。主题是技术革命与中国振兴。当时技术革命的热点是光纤维。当时普遍认为中国比发达国家落后几十年，赶超世界是一个遥远的梦想。汪应洛教授指出，中国不需要走西方的老路，不需要先普及电话，再建设互联网。在光纤维的时代，中国与世界站在同一个起跑线上。光纤维是中国振兴的一个机会。