Simulation of Gas-Water Two-Phase Flow in Tight Gas Reservoirs Considering the Gas Slip Effect

A mathematical model for the gas-water two-phase flow in tight gas reservoirs is elaborated.The model can account for the gas slip effect,stress sensitivity,and high-speed non-Darcy factors.The related equations are solved in the framework of a finite element method.The results are validated against those obtained by using the commercial software CMG(Computer Modeling Group software for advanced recovery process simulation).It is shown that the proposed method is reliable.It can capture the fracture rejection characteristics of tight gas reservoirs better than the CMG.A sensitivity analysis of various control factors(initial water saturation,reservoir parameters,and fracturing parameters)affecting the production in tight gas wells is conducted accordingly.Finally,a series of theoretical arguments are provided for a rational and effective development/exploitation of tight sandstone gas reservoirs.

Slip effects on shearing flows in a porous medium

This paper deals with the magnetohydrodynamic （MHD） flow of an Oldroyd 8-constant fluid in a porous medium when no-slip condition is no longer valid. Modified Darcy＇s law is used in the flow modelling. The non-linear differential equation with non-linear boundary conditions is solved numerically using finite difference scheme in combination with an iterative technique. Numerical results are obtained for the Couette, Poiseuille and generalized Couette flows. The effects of slip parameters on the velocity profile are discussed.

Natural convection flow of a couple stress fluid between two vertical parallel plates with Hall and ion-slip effects

The Hall and ion-slip effects on fully developed electrically conducting couple stress fluid flow between vertical parallel plates in the presence of a temperature dependent heat source are investigated. The governing non-linear partial differential equations are transformed into a system of ordinary differential equations using similarity transformations. The resulting equations are then solved using the homotopy analysis method （HAM）. The effects of the magnetic parameter, Hall parameter, ion-slip parameter and couple stress fluid parameter on velocity and temperature are discussed and shown graphically

Reiner-Rivlin nanomaterial heat transfer over a rotating disk with distinct heat source and multiple slip effects

The thermodynamic features of the Reiner-Rivlin nanoliquid flow induced by a spinning disk are analyzed numerically.The non-homogeneous two-phase nanofluid model is considered to analyze the effect of nanoparticles on the thermodynamics of the Reiner-Rivlin nanomaterial,which also includes a temperature-dependent heat source(THS)and an exponential space-dependent heat source(ESHS).Further,the transfer of heat and mass is analyzed with velocity slip,volume fraction jump,and temperature jump boundary conditions.The finite difference method-based routine is used to solve the complicated differential equations formed after using the von-Karman similarity technique.Limiting cases of the present problem are found to be in good agreement with benchmarking studies.The relationship of the pertinent parameters with the heat and mass transport is scrutinized using correlation,which is further evaluated based on the probable error estimates.Multivariable models are fitted for the friction factor at the disk and heat transport,which accurately predict the dependent variables.The Reiner-Rivlin nanoliquid temperature is influenced comparatively more by the ESHS than by THS.The Nusselt number is decreased by the ESHS and THS,whereas the friction factor at the disk is predominantly decremented by the wall roughness aspect.The increment in the non-Newtonian characteristic of the liquid leads more fluid to drain away in the radial direction far from the disk compared with the fluid nearby the disk in the presence of the centrifugal force during rotation.The increased thermal and volume fraction slip lowers the nanoliquid temperature and nanoparticle volume fraction profiles.

Numerical Solution for Variable Accelerated Flow Subject to Slip Effect

In this paper, we examine the unsteady magneto hydrodynamic (MHD) flow generated by a disc that is making non-coaxial rotations with a third grade fluid at infinity and moving with a variable acceleration. The fluid is assumed to satisfy slip boundary condition on the disc. The governing equations are three dimensional and highly non-linear in nature. The assumed slip boundary condition is non-linear as well. The governing equations are transformed to a nonlinear boundary value problem which is solved numerically. Comparison of this generalized problem with uniformly accelerated disk satisfying no slip condition is made. Variations of the characterizing dimensionless parameters such as slip parameter λ, acceleration parameter c, unsteady parameter τ, third grade parameter β, suction parameter S, and magnetic parameter N on the flow field are discussed and analyzed graphically.

A Clot Model Examination: with Impulsion of Nanoparticles under Influence of Variable Viscosity and Slip Effects

In this speculative analysis, our main focused is to address the neurotic condition that occurs due to accumulation of blood components on the wall of the artery that results in blood coagulation. Specifically, to perceive this phenomena clot model is considered. To discuss this analysis mathematical model is formed in the presence of the effective thermal conductivity and variable viscosity of base fluid. Appropriate slip conditions are employed to obtain the close form solutions of temperature and velocity profile. The graphical illustrations have been presented for the assessment of pressure rise, pressure gradient and velocity profile. The effects of several parameters on the flow quantities for theoretical observation are investigated. At the end, the results confirmed that the impulsion of copper and silver nanoparticles as drug agent enlarges the amplitude of the velocity and hence nanoparticles play an important role in engineering and biomedical applications such as drug delivery system.

Effect of slip velocity on Casson thin film flow and heat transfer due to unsteady stretching sheet in presence of variable heat flux and viscous dissipation

The aim of the present paper is to study flow and heat transfer charac- teristics of a viscous Casson thin film flow over an unsteady stretching sheet subject to variable heat flux in the presence of slip velocity condition and viscous dissipation. The governing equations are partial differential equations. They are reduced to a set of highly nonlinear ordinary differential equations by suitable similarity transformations. The re- sulting similarity equations are solved numerically with a shooting method. Comparisons with previous works are macle, and the results are found to be in excellent agreement. In the present work, the effects of the unsteadiness parameter, the Casson parameter, the Eckert number, the slip velocity parameter, and the Prandtl number on flow and heat transfer characteristics are discussed. Also, the local skin-friction coefficient and the local Nusselt number at the stretching sheet are computed and discussed.

Flow behavior in microchannel made of different materials with wall slip velocity and electro-viscous effects

In a microfluidic system, flow slip velocity on a solid wall can be the same order of magnitude as the average velocity in a microchannel. The flow-electricity interaction in a complex microfluidic system subjected to joint action of wall slip and electro-viscous effect is an important topic. This paper presents an analytic solution of pressuredriven liquid flow velocity and flow-induced electric field in a two-dimensional microchannel made of different materials with wall slip and electro-viscous effects. The Poisson- Boltzmann equation and the Navier-Stokes equation are solved for the analytic solutions. The analytic solutions agree well with the numerical solutions. It was found that the wall slip amplifies the fow-induced electric field and enhances the electro-viscous effect on flow. Thus the electro-viscous effect can be significant in a relatively wide microchannel with relatively large kh, the ratio of channel width to thickness of electric double layer, in comparison with the channel without wall slip.

Slip on the surface of silicon wafers under laser irradiation:Scale effect

The slip mechanism on the surface of silicon wafers under laser irradiation was studied by numerical simulations and experiments. Firstly, the slip was explained by an analysis of the generalized stacking fault energy and the associated restoring forces. Activation of unexpected {110} slip planes was predicted to be a surface phenomenon. Experimentally,{110} slip planes were activated by changing doping concentrations of wafers and laser parameters respectively. Slip planes were {110} when slipping started within several atomic layers under the surface and turned into {111} with deeper slip.The scale effect was shown to be an intrinsic property of silicon.

Closed-form solution for shear lag effects of steel-concrete composite box beams considering shear deformation and slip

Based on the consideration of longitudinal warp caused by shear lag effects on concrete slabs and bottom plates of steel beams,shear deformation of steel beams and interface slip between steel beams and concrete slabs,the governing differential equations and boundary conditions of the steel-concrete composite box beams under lateral loading were derived using energy-variational method.The closed-form solutions for stress,deflection and slip of box beams under lateral loading were obtained,and the comparison of the analytical results and the experimental results for steel-concrete composite box beams under concentrated loading or uniform loading verifies the closed-form solution.The investigation of the parameters of load effects on composite box beams shows that:1) Slip stiffness has considerable impact on mid-span deflection and end slip when it is comparatively small;the mid-span deflection and end slip decrease significantly with the increase of slip stiffness,but when the slip stiffness reaches a certain value,its impact on mid-span deflection and end slip decreases to be negligible.2) The shear deformation has certain influence on mid-span deflection,and the larger the load is,the greater the influence is.3) The impact of shear deformation on end slip can be neglected.4) The strain of bottom plate of steel beam decreases with the increase of slip stiffness,while the shear lag effect becomes more significant.

Influence of permeation effect on themicrofabric of the slip zone soils: A case study from the Huangtupolandslide

This study aims to investigate the correlation between the permeation effect and microfabric of the slip zone soils with Huangtupo landslide in the Three Gorges Reservoir as the study case. Based on the permeability test and scanning electron microscope(SEM) images analysis, the fractal theory and probability entropy are used to quantify the characteristics of the remodeling specimens. First, the relationships between initial moisture content(IMC) and microstructure of the soil(percentage of particle area(PPA), pore roundness(Rp)) before and after permeability test are summarized. Then, the fractal dimension of the soil(pore distribution(Dpd), pore size(Dps)) are analyzed under the permeation effect. Based on the probability entropy, the entropy of pore(Ep) is used to characterize the porosity orientation, and the rose diagrams are used to show the particle orientation under the permeation effect. Finally, the relationship between the microstructure of the soil and its mechanical property is discussed. Results show that under the permeation effect, the microstructure of the soil has undergone tremendous changes. A flat long pore channel is formed. The order of the pore arrangement is enhanced, and soil particles switch the long axis to parallel infiltration direction to reach a new steady state. It can be inferred that the strength of soil would be weakened if the fractal dimension of soil pore decreases under any external environment.

SYNCHRONOUS EFFECT OF SLIPPING HEAVY LOADS ON RO-RO SHIP ROLLING IN WAVES

Common effect of wave and slip of internal vehicles will make rolling of the roll-on ship serious. This is one of the important reasons for overturn of ro-ro ships. The multibody system with a floating base is composed of ro-ro ship and slipping vehicles. Takes the rolling angle of the ship and the transverse displacements of the slipping vehicles on desk as freedoms. Making use of the analysis of apparent gravitation and apparent buoyancy, the wave rolling moment is derived. By means of dynamic method of multibody system, dynamic equations of the system are established. Taking a certain channel ferry as an example, a set of numerical calculation have been carried out for rolling response of the multibody system with a floating base of a ro-ro ship and displacements response of the slipping vehicles under common effect of free slipping vehicles and wave, and a conclusion has been drawn that the motion of the numerous free slipping heavy loads will trend to be synchronous under restraining of the side-wall bulkhead with time because of repeated collision.

基岩油气成藏特征与中国陆上深层基岩油气勘探方向

基于全球基岩油气藏数据库和中国基岩油气藏解剖,深入分析基岩油气成藏特征,探讨深层基岩油气成藏的有利条件和勘探方向。研究表明:全球已发现的基岩油气田主要分布在埋深小于4500 m的中浅层,层位以太古宇和前寒武系为主,储集层岩性以花岗岩和变质岩为主;规模较大的基岩油气田主要分布在中新生代构造运动活跃的裂谷盆地、弧后盆地和前陆盆地。基岩油气成藏特征主要表现为:(1)以孔隙-裂缝型低孔特低渗储集层为主,非均质性强,强抗压实作用导致储集层物性不受埋深控制,规模成储期为盆地基底风化剥蚀期及后期构造改造期;(2)他源供烃,成藏组合可划分为烃源岩-基岩接触型和烃源岩-基岩分离型两大类;(3)烃源岩异常高压和基岩储集层常压-低压,导致烃源岩与储集层之间存在较大的压力差,有利于深层基岩抽吸成藏。基底构造活动性、成藏组合关系、深大断裂(尤其走滑断裂)发育程度及区域性盖层等是深层基岩选区评价的主要参数;古老克拉通盆地陆内裂谷边缘的前寒武系结晶基底、紧邻生烃凹陷的古生代褶皱基底和中新生代块断基底,均具有较好的成藏条件,是未来深层基岩油气勘探的主要方向。

新型可拆卸式钢-UHPC组合板的抗弯性能

为探究钢-薄层超高性能混凝土(ultra-high performance concrete,UHPC)轻型组合桥面体系在局部轮载下的抗弯性能,设计并开展了4块基于高强螺栓连接的可拆卸式钢-UHPC组合板的四点弯曲试验,研究了钢板类型、抗剪连接件间距对可拆卸式钢-UHPC组合板的破坏模式、荷载-挠度曲线、界面相对滑移、裂缝宽度、截面应变分布等影响规律,研究结果表明:在正弯矩荷载作用下,采用Q355钢板的组合板的破坏模式为高强螺栓被剪断,而采用负泊松比(negative Poisson’s ratio,NPR)钢板的组合板的破坏模式为部分高强螺栓被剪断、部分预埋带垫加长螺母被拔出、UHPC板由于失稳大面积压溃等;在相同的高强螺栓间距下,采用NPR钢板的组合板的板端相对滑移较小,说明NPR钢板有效延缓并限制了钢板与UHPC板的相对滑移,从而提升两者的协同变形能力,继而提高组合板的抗弯刚度及承载力等;由截面应变分析可知,由于NPR钢板的负泊松比效应、高刚度、高屈服强度,整个加载过程NPR钢板与底部UHPC层的拉应变保持着应变协调性,随着荷载的增大截面塑性中和轴的上移幅度可忽略不计。因此,在采用NPR钢板提升钢-UHPC组合板抗弯性能的前提下,应使UHPC厚度与NPR钢板的性能进行匹配,充分发挥两者的材料性能,避免失稳破坏先于UHPC材料强度破坏。

基于CT扫描技术的煤样三维重构及气体表观渗透率研究

基于CT扫描技术对煤样扫描成像,并进行滤波和二值化处理,获取孔裂隙尺寸、孔隙率等特征参数。通过盒维法计算煤样的分形维数,推导煤样孔裂隙的平均迂曲度及迂曲度维数。结合分形理论和克努森数,推导煤体中经滑移修正的气体表观渗透率模型并进行验证。通过ANASY有限元软件研究煤体中的瓦斯渗流规律。结果表明,瓦斯在孔裂隙弯折处压力变化剧烈,渗流速度在孔裂隙弯折处达到最大,瓦斯在个别孔隙发生凝滞、不流通。采用经过滑移修正的气体表观渗透率模型计算瓦斯表观渗透率,并与通过Forchheimer公式拟合得到的瓦斯表观渗透率及通过FT模型计算得到的瓦斯表观渗透率相比较,发现经过滑移修正后的气体表观渗透率模型适用于微尺度介质中气体表观渗透率研究。

考虑滑移的钢-混凝土组合箱梁畸变效应研究

通过引入滑移转角位移函数,建立考虑滑移的畸变翘曲正应力,基于势能驻值原理,推导考虑滑移效应的畸变微分方程。定义了一个畸变的滑移影响系数κ,此系数仅与混凝土与钢材材料特性、栓钉类型及栓钉布置形式有关,并给出均布荷载和集中荷载作用下的微分方程初参数解。建立一个考虑滑移的钢-混凝土组合箱梁的Ansys有限元模型,均布荷载作用下畸变应力与畸变角与本文理论吻合良好,验证了本文理论的正确性。将考虑滑移与不考虑滑移的结果进行对比,分析表明,均布荷载作用下考虑滑移的畸变角与畸变翘曲均小于不考虑滑移的情况,且考虑滑移的畸变角更加接近于有限元计算结果。重新定义了考虑滑移的畸变矩和畸变双力矩且考虑滑移影响的结果均大于不考虑滑移的结果。

考虑波形腹板剪切的端部固支组合梁挠度分析

波形钢腹板组合梁因其优良性能得到广泛应用,其挠度问题是研究的重点之一,近年来我国对波形钢腹板组合梁挠度计算方法的研究虽有长足的进步,但多集中于静定结构,并且端部固支的超静定结构体系在桥梁工程中应用广泛。为了探讨不同支承下波形钢腹板组合梁滑移附加挠度变化的规律,并为波形钢腹板组合梁的后续研究提供理论基础和参考,在足够刚度的前提下将端部固支波形钢腹板梁简化为两端固支和一端固支一端活动铰支的端部约束条件,推导了其考虑滑移和腹板剪切变形影响时的跨中挠度计算公式,找到适用于实际桥型的挠度计算方法;基于试验梁和有限元模型对本文公式进行了验证,结果表明:端部固支波形钢腹板组合梁的滑移附加挠度占比随剪切刚度的变化趋势显著区别于一端固定铰支一端活动铰支的抛物线型而呈线性变化;不对称约束放大了波形钢腹板组合梁腹板的剪切变形和滑移效应。

近直下型断层的地铁车站结构地震响应

目前在近断层场地中地下地铁车站抗震性能水平认识方面相对匮乏,鉴于此,提出了一种考虑发震断层-地下结构全过程地震响应的IBE-FEM联合求解分析方法。首先,基于运动学有限断层模型,采用间接边界元方法(IBE)求解直下型走滑断层错动作用下上覆软土沉积层场地内的地震波场,并验证了有限元法(FEM)间接求解地震波场的可行性;在此基础上,通过建立土-地下连续墙-主体结构非线性静-动力耦合的二维整体时域有限元模型,初步探究了断层-软土场地耦合效应对地铁车站抗震性能的影响规律。结果表明:在近断层区域,地铁车站结构震害具有典型的断层上盘效应和震害集中效应,更容易进入塑性变形发展阶段;在远断层区域,由于断层-场地效应耦合作用,断层下盘场地内地震波场衰减较缓,其内车站结构整体震害略大于断层上盘。本文研究方法为近断层场地条件下地下结构地震响应分析开辟新思路,也可为相关场地区域内的地下结构抗震设计提供技术参考。

Lattice Boltzmann Simulations of the Klinkenberg Effect in Porous Media

格子Boltzmann数值模拟方法是研究复杂的多孔介质结构特别是Klinkenberg效应的有效方法之一,对处理复杂边值问题尤其有效.用格子Boltzmann方法研究了气流穿越多孔介质问题,并将数值计算结果与实验结果进行了比较,结果表明格子Boltzmann方法是数值模拟气流穿越多孔介质问题的有效方法之一.

内饰材料摩擦异响兼容性研究

为了在汽车内饰正向开发流程中提前降低内饰摩擦异响风险,减少实物验证的试错周期和成本。文章介绍了材料粘滑效应基本原理和材料粘滑摩擦试验,分析了常用内饰材料在不同工况下的摩擦异响风险等级,建立了常温常湿工况下常用内饰材料摩擦异响兼容数据库,为产品设计前期材料选择提供了指导。同时介绍了内饰材料异响兼容数据库的工程应用,指导了内饰摩擦异响的正向管控。