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Physical mechanics investigation into carbon utilization and storage with enhancing shale oil and gas recovery

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Science China(Technological Sciences) 2022年第2期65卷 490-492页

作者： zhao yapu State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Over the last decade, the boom in hydrocarbon recovery from shale formations has revolutionized the world energy landscape [1–3]. This unconventional energy contributes to lower carbon dioxide (CO_(2)) and other criteria pollutant emissions. However, its extraction technologies, namely horizontal drilling and hydraulic fracturing (fracking), pose environmental risks. To address this environmental controversy, an option is to use supercritical CO_(2) to achieve waterless fracking. This is a feasible, economic.

关键词： shale formations landscape

Bridging length and time scales in moving contact line problems

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Science China(Physics,Mechanics & Astronomy) 2016年第11期59卷 87-89页

作者： yapu zhao State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of Sciences Beijing 100049China

Physical,mechanical,chemical,and biological processes for various problems span length and time scales of many orders of magnitude[1-6].As a typical dynamic process,moving contact line（MCL）problem or droplet spreading consists of 7-8 length and time scales from the atomistic to the continuum[2],as shown in Figure 1.A grand challenge in MCL problems is to link these vastly different length and time *** these length and time scales origin from the competition among governing forces[7],

关键词：时间尺度移动接触线长度桥接生物过程 MCL 数量级连续性

SELF-INSTABILITY AND BENDING BEHAVIORS OF NANO PLATES

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Acta Mechanica Solida Sinica 2009年第6期22卷 630-643页

作者： Zhiqiao Wang yapu zhao State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

This paper aims at investigating the size-dependent self-buckling and bending behaviors of nano plates through incorporating surface elasticity into the elasticity with residual stress fields. In the absence of external loading, positive surface tension induces a compressive residual stress field in the bulk of the nano plate and there may be self-equilibrium states corresponding to the plate self-buckling. The self-instability of nano plates is investigated and the critical self-instability size of simply supported rectangular nano plates is determined. In addition, the residual stress field in the bulk of the nano plate is usually neglected in the existing literatures, where the elastic response of the bulk is often described by the classical Hooke＇s law. The present paper considered the effect of the residual stress in the bulk induced by surface tension and adopted the elasticity with residual stress fields to study the bending behaviors of nano plates without buckling. The present results show that the surface effects only modify the coefficients in corresponding equations of the classical Kirchhoff plate theory.

关键词： nano plates self-buckling surface tension residual stress

THE UNIQUE PROPERTIES OF THE SOLID-LIKE CONFINED LIQUID FILMS:A LARGE SCALE MOLECULAR DYNAMICS SIMULATION APPROACH

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Acta Mechanica Solida Sinica 2011年第2期24卷 101-116页

作者： Fengchao Wang yapu zhao State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

The properties of the confined liquid are dramatically different from those of the bulk state, which were reviewed in the present work. We performed large-scale molecular dynamics simulations and full-atom nonequilibrium molecular dynamics simulations to investigate the shear response of the confined simple liquid as well as the n-hexadecane ultrathin films. The shear viscosity of the confined simple liquid increases with the decrease of the film thickness. Apart from the well-known ordered structure, the confined n-hexaxiecane exhibited a transition from 7 layers to 6 in our simulations while undergoing an increasing shear velocity. Various slip regimes of the confined n-hexadecane were obtained. Viscosity coefficients of individual layers were examined and the results revealed that the local viscosity＇coefficient varies with the distance from the wall. The individual n-hexadecane layers showed the shear-thinning behaviors which can be correlated with the occurrence of the slip. This study aimed at elucidating the detailed shear response of the confined liquid and may be used in the design and application of microand nano-devices.

关键词： confined liquid solid-like shear-thinning slip large scale molecular dynamics simulation

The effect of surface anisotropy on contact angles and the characterization of elliptical cap droplets

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Science China(Technological Sciences) 2018年第2期61卷 309-316页

作者： WANG ZhanLong CHEN EnHui zhao yapu State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

In this paper, the variation of contact angles of a droplet on grooved surfaces was studied from microscale to macroscale experimentally and theoretically. The experimental results indicated that the contact angle changes nonlinearly with anisotropic factor. To get clear of the changing process of contact angle on grooved surfaces from microscale to macroscale, we carried out theoretical analysis with moment equilibrium method being adopted. In addition, the variation of contact angles in different directions was investigated and a mathematic model to calculate arbitrary contact angles around the elliptic contact line was suggested. For the convenience of potential applications, a symbolic contact angle was proposed to characterize the ellipsoidal cap droplet on grooved surfaces. Our results will offer help to the future design of patterned surfaces in practical applications,and deepen the understanding of wetting behavior on grooved surfaces.

关键词： droplet contact angle ellipse contact line grooved surface

Solute transport and interface evolution in dissolutive wetting

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Science China(Physics,Mechanics & Astronomy) 2019年第12期62卷 48-56页

作者： JinHong Yang QuanZi Yuan yapu zhao State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Dissolutive wetting, i.e., droplet wetting on dissolvable surfaces, is essential for various natural phenomena and industrial applications such as the formation of sinkholes, enhancing shale gas recovery, drug design, MEMS, and so on. It is difficult to predict the evolution of concentration field and solid-liquid interface owing to the coupled effects of wetting, diffusion, and convection. This study makes substantial progress by proposing a new theory based on Onsager’s variational principle and finding two modes of solute transport, i.e., shifting and lifting modes. Furthermore, we investigate the influence of wetting and dissolution coupling on the interface shape using a phase diagram. Using our theory, we can predict and inversely predict the interface evolution.

关键词： wetting diffusion solid-liquid interface concentration distribution

Formation of wavy-ring crack in drying droplet of protein solutions

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Science China(Technological Sciences) 2018年第7期61卷 949-958页

作者： GAO MengNi HUANG XianFu zhao yapu State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences School of Engineering Science University of Chinese Academy of Sciences

The formations of desiccation cracks and their pattems in drying droplets of protein solutions are studied experimentally. The solvent evaporation causes the dehydration self-organization phenomenon in colloidal droplets, followed by the formations of desiccation cracks. Two categories of highly ordered crack patterns, which we name ＂daisy＂ and ＂wavy-ring＂, are identified in the drying droplets. We explore the shifting of crack patterns from the ＂daisy＂ to the ＂wavy-ring＂ by varying the concentration of protein droplets. The results show that the concentration correlates with the pattern of deposition film directly, and modulates the periodicity of the crack pattern. We investigate the formations and periodicities of these two kinds of crack patterns, and obtain the scaling law of periodicity of the ＂wavy-ring＂ crack pattern. The relationship between the deposition pattern and the highly ordered crack patterns is also examined. This study will help in understanding the formation mechanisms of crack patterns in drying droplets of protein solutions and assist the future design of crack patterns in practical applications.

关键词： coffee-ring effect spiral crack self-organization crack pattern desiccation

Molecular dynamics simulation of peeling a DNA molecule on substrate

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Acta Mechanica Sinica 2005年第3期21卷 249-256页

作者： Xinghua Shi Yong Kong yapu zhao Huajian Gao Max-Planck Institut für Metallforschung Heisenbergstr. 3 D-70569 Stuttgart Germany State Key Laboratory of Nonlinear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences. Beijing 100080 China

Molecular dynamics （MD） simulations are performed to study adhesion and peeling of a short fragment of single strand DNA （ssDNA） molecule from a graphite surface. The critical peel-off force is found to depend on both the peeling angle and the elasticity of ssDNA. For the short ssDNA strand under investigation, we show that the simulation results can be explained by a continuum model of an adhesive elastic band on substrate. The analysis suggests that it is often the peak value, rather than the mean value, of adhesion energy which determines the peeling of a nanoscale material.

关键词： Molecular dynamics simulation DNA Adhesion Peeling

Understanding formation mechanism of ZnO diatomic chain and multi-shell structure using physical mechanics:Molecular dynamics and first-principle simulations

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Science China(Physics,Mechanics & Astronomy) 2012年第6期55卷 1138-1146页

作者： WANG BinBin WANG FengChao zhao yapu State Key Laboratory of Nonlinear Mechanics(LNM) Institute of MechanicsChinese Academy of SciencesBeijing 100190China

In this paper,the possibility of the monatomic chain (MC) formation for ZnO material was studied by molecular dynamics (MD) *** process of MC formation and the effects of temperature,strain rate and size were studied *** tensile process can be divided to be five stages and the ZnO diatomic chain (DC) can be *** MD results show that most atoms in MC came from the original surface of ZnO nanowires (NWs).Temperature and strain rate are two important factors affecting the process,and both high temperature and low strain rate in a certain range would be beneficial to the formation of ***,the effects of strain rate and temperature could attribute to the Arrhenius model and the energy release ***,multi-shell structure was found for the samples under tensile strain and the layer-layer distance was about *** studies based on density functional theory showed that the most stable structure of ZnO DC was confirmed to be linear,and the I-V curve was also got using ATK.

关键词： diatomic chain multi-shell structure ZnO size effect temperature and strain rate effects