Study of the Influence of Nanoparticles on the Molecular Model of an Ideal Fluid

In the article a molecular model of oil with nanoparticles on the basis of the model of ideal fluid is considered. It is assumed that the molecular model of the oil can be represented as a homogenous distribution of identical molecules in space. It is assumed that the central interaction between the oil molecules and nanoparticles, results in a change of the model parameters. It is shown that for an ideal fluid the effect of nanoparticles is reduced to a change of the coefficient at the pressure.

A Finite-Mode Model of Ideal Fluid Dynamics on the 2-Sphere

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CVBEM and FVM Computational Model Comparison for Solving Ideal Fluid Flow in a 90-Degree Bend

While finite volume methodologies (FVM) have predominated in fluid flow computations, many flow problems, including groundwater models, would benefit from the use of boundary methods, such as the Complex Variable Boundary Element Method (CVBEM). However, to date, there has been no reporting of a comparison of computational results between the FVM and the CVBEM in the assessment of flow field characteristics. In this work, the CVBEM is used to develop a flow field vector outcome of ideal fluid flow in a 90-degree bend which is then compared to the computational results from a finite volume model of the same situation. The focus of the modelling comparison in the current work is flow field trajectory vectors of the fluid flow, with respect to vector magnitude and direction. Such a comparison is necessary to validate the development of flow field vectors from the CVBEM and is of interest to many engineering flow problems, specifically groundwater modelling. Comparison of the CVBEM and FVM flow field trajectory vectors for the target problem of ideal flow in a 90-degree bend shows good agreement between the considered methodologies.

Designing Drill-in Fluids by Using Ideal Packing Technique

Selecting bridging agents properly is a critical factor in designing non-damaging or low-damaging drill-in fluids. Historically, Abrams＇ rule has been used for this purpose. However, Abrams＇ rule only addresses the size of particle required to initiate a bridge. The rule does not give an optimum size nor an ideal packing sequence for minimizing fluid invasion and optimizing sealing. This paper elaborates an ideal packing approach to solving the sealing problem by sealing pores with different sizes, especially those large pores which usually make dominant contribution to permeability and thereby effectively preventing the solids and filtrate of drill-in fluids from invading into formations, compared with the conventionally used techniques. Practical software has been developed to optimize the blending proportion of several bridging agents, so as to achieve ideal packing effectiveness. The method and its use in selecting the best blending proportion of several bridging agents are also discussed in this paper. A carefully designed drill-in fluid by using the ideal packing technique （named the IPT fluid） for offshore drilling operations at the Weizhou Oilfield, Nanhai West Company, CNOOC is presented. The near 100% return permeabilities from the dynamic damage tests using reservoir cores demonstrated the excellent bridging effect provided by this drill-in fluid.

关于欧拉方程和伯努利方程适用条件的探讨

从动量守恒和能量守恒出发,详细地阐述了欧拉方程和伯努利方程的推导过程。从两个方程的推导过程可以清楚地看到,欧拉方程适用的充要条件是黏性偏应力张量的散度为零,流体黏度为零只是欧拉方程成立的充分条件而非必要条件。伯努利方程除了需要适用欧拉方程外,还需要满足流体正压、质量力有势、流动定常的条件,如果需要保持系统的总能量守恒,则正压流体条件需改为等熵流动条件。

Rheological property of low-damage,ideal packing,film-forming amphoteric/sulfonation polymer drilling fluids

Low-permeability dense reservoirs,including micro-fractured reservoirs,are commonly characterized by high content of clay substances,high original water saturation,high sensitivity to invasive fluids,high capillary pressure,complicated structure and anisotropic,high flow-resistance and micro pore throats etc,.Generally they also have lots of natural micro fractures,probably leading to stress sensibility.Main damaging factors in such reservoirs are water-sensibility and water-blocking caused by invasive fluids during drilling and production operations.Once damaged,formation permeability can rarely recovered.Numerous studies have shown that damaging extent of water-blocking ranges from 70% to 90%.Main damaging mechanisms and influencing factors of water-blocking were systematically analyzed.Also some feasible precaution or treating approaches of water-blocking were put forward.In a laboratory setting,a new multi-functional drilling fluid composed mainly of amphion polymer,sulfonation polymer,high effectively preventive water-blocking surfactants,ideal packing temporary bridging agents(TBA) and film-forming agents,etc.,were developed.New low-damage drilling fluids has many advantages,such as good rheological properties,excellent effectiveness of water-blocking prevention,good temporary plugging effect,low filtration and ultra-low permeability(API filtration≤5 mL,HTHP filtration≤10 mL,mud cake frictional coefficient≤0.14,permeability recovery>81%),can efficiently prevent or minimize damage,preserve natural formation and enhance comprehensive development-investment effect in TUHA Jurassic dense sandstone reservoir formation with low-permeability,the only one developing integrated condense gas field.Some references can be provided to similar reservoir formations.

Analytical solutions for dynamic pressures of coupling fluid-solid-porous medium due to P wave incidence

Wave reflection and refraction in layered media is a topic closely related to seismology,acoustics,geophysics and earthquake engineering.Analytical solutions for wave reflection and refraction coefficients in multi-layered media subjected to P wave incidence from the elastic half-space are derived in terms of displacement potentials.The system is composed of ideal fluid,porous medium,and underlying elastic solid.By numerical examples,the effects of porous medium and the incident wave angle on the dynamic pressures of ideal fluid are analyzed.The results show that the existence of the porous medium,especially in the partially saturated case,may significantly affect the dynamic pressures of the overlying fluid.

Hypothetical Dark Matter Explains the Origin of Subatomic Universe: FEP-Theory

Although the standard model provides a suitable pattern based on observable experimental data, it cannot explain dark matter, gravitation, the structural nature of the fundamental particles, and charges. In this paper, a new theory about the nature of charges, particles and proposed structures for atoms were presented. This theory explains how an ideal quantum fluid (IQF) including hypothetical dark matter or fundamental elementary particles (FEPs) can produce the building blocks of matter. This theory describes quadruple blocks with two types of independent charges that can create different characteristics for these building blocks. Quadruple blocks have similarities and differences with the fundamental particles in standard model. This theory also explains the possible mechanism of creation the next generation of particles such as protons and neutrons.

求细气柱对垂直静止平板吹力的两种方法及与风力比较

给出求细气柱对垂直静止平板吹力的两种方法,即动量定理法与动能定理法,并指出后一种解法中的参考系切换与伽利略速度变换的思想,同时也指出这两种解法的物理前提便是细气柱为流速不太大的理想流体.作为对比,又分析给出风对圆形垂直静止平板吹力的表达式,并将其与细气柱对垂直静止平板的吹力进行对比,指出其中显著差异的原因在于物理机制上的不同——风在与平板相互作用时存在绕流现象,并且已不是理想流体,其内部在绕流后存在着明显的湍流迹象.

IDEAL算法在OpenFOAM界面两相流求解器中的实现与性能分析

针对IDEAL算法在界面两相流数值模拟中的应用主要基于结构化网格或二维非结构化网格,难以在复杂问题中推广应用的难题,将IDEAL算法植入到了开源计算流体力学软件OpenFOAM的界面两相流求解器interFoam中,然后通过二维液柱倒塌、二维单气泡上升、三维异轴双气泡上升以及三维起伏管段气液两相流4个算例对IDEAL算法与OpenFOAM软件中采用的PIMPLE算法进行了计算性能分析。研究结果表明:IDEAL算法的计算时间较PIMPLE算法减少了17.6%^+∞;在部分工况下PIMPLE算法难以收敛,而IDEAL算法仍然可以快速获得收敛解。研究结果为IDEAL算法在复杂界面两相流问题中的推广奠定了基础。

Experimental study of low-damage drilling fluid to minimize waterblocking of low-permeability gas reservoirs

This paper discusses the systematic design and development of low-damage drilling fluid to protect the low-permeability gas reservoir of the Sulige block in the Ordos Basin, Inner Mongolia Autonomous Region, China. Based on investigation of the geological characteristics and the potential formation damage of the Permian formation of the reservoir, waterblocking due to invasion of drilling or completion fluids was identified one of the most severe causes of damage to gas well deliverability. By adopting the phase trap prevention method, ideal packing theory, and film-forming technology, a lowdamage drilling fluid, sodium formate brine containing efficient waterblocking preventing surfactants, optimized temporary bridging agents （TBAs）, and film-forming agents has been developed. The performance of the new drilling fluid was evaluated by using a variety of techniques. The results show that the fluid has good rheological properties, good strong shale-swelling inhibition, good temporary plugging effect, ultra-low filtration, and good lubricity. It can efficiently minimize waterblocking and can be used to drill horizontal wells with minimal intervention of the reservoir in the Sulige Gas Field.

非理想气体工质对内可逆Otto循环功率、效率性能的影响

基于有限时间热力学理论和内可逆Otto循环模型,进一步考虑非理想气体工质比热模型,对循环的功率和效率性能进行研究。通过数值计算分析比热模型、气体分子自由度d和传热损失B对循环最大功率Po_(t max)、最大效率η_(max)、Po_(t max)对应的最佳压缩比(γopt_(p)和效率ηP、η_(max)对应的最佳压缩比(γopt_(η)和功率Pη的影响。结果显示:循环性能η_(max)、(γopt_(η)和η_(p)随着B的增大而减小;工质比热模型对循环性能不产生定性影响,仅产生定量影响,非理想气体比热模型条件下的循环Po_(t max)、(γopt_(p)、η_(max)、(γopt_(η)、η_(p)和Pη均小于其他两种比热模型;循环性能(Pot)_(max)、(γopt_(p)、η_(max)、(γopt)_(η)、η_(p)和P_(η)随着d的增大而增大。研究结果对内燃机设计具有一定的指导意义。

肾动脉非对称理想化血管模型的计算流体力学研究

背景 在胸腹主动脉疾病的腔内治疗中,重建肾动脉至关重要。既往针对肾动脉的计算流体力学分析往往通过支架置入后的理想化三维血管模型进行,这些模型中左右肾动脉形态往往是对称且不符合生理的。目的 构建置入多分支支架后的理想化胸腹主动脉三维模型,并基于我国人群的肾动脉解剖条件,探究生理性非对称肾动脉形态对理想化模型双肾动脉内的血液流动所产生的影响。方法 根据肾动脉角度及肾动脉支架长度的不同,共构建16种理想化模型,之后通过计算流体力学对这些模型分支血管的平均血流量、血液流动模式和壁面剪切应力进行研究。结果 肾动脉角度为95°时的平均血流量大于角度为108°时的平均血流量。肾动脉支架长度为60 mm时的平均血流量大于长度为70 mm时的平均血流量。此外,在肾动脉拐弯处可见血液回流区和低壁面剪切应力区。结论 本文构建了肾动脉生理性非对称的理想化多分支支架置入后血管模型,并通过计算流体力学研究发现非对称的肾动脉形态可对肾动脉平均血流量产生影响。在肾动脉理想化模型的构建中,非对称的解剖形态是必要的。

A Theoretical Study on Energy of a Gaseous System Vis-a-Vis Mass and Temperature

To study various properties of a gas has been a subject of rational curiosity in pneumatic sciences. A gaseous system, in general, is studied by using four measurable parameters namely, the pressure, volume, number of moles and temperature. In the present work, an attempt is made to study the variation of energy of an ideal gas with the two measurable parameters, the mass and temperature of the gas. Using the well known ideal gas equation, PV = nRT where symbols have their usual meanings and some simple mathematical operations widely used in physics, chemistry and mathematics in a transparent manner, an equation of state relating the three variables, the energy, mass and temperature of an ideal gas is obtained. It is found that energy of an ideal gas is equal to the product of mass and temperature of the gas. This gives a direct relationship between the energy, mass and temperature of the gas. Out of the three variables, the energy, mass and temperature of an ideal gas, if one of the parameters is held constant, the other two variables can be measured. At a constant temperature, when the power or energy is stabilized, the increase in the mass of the gas may affect the new works and an engine can therefore be prevented from overheating.

水下声源引起的水表面横向微波的理论研究

利用水下声信号在水表面引起的水表面横向微波振幅很小的条件,将普遍的流体力学方程线性化,推导出在水下点声源的激励下,水表面产生的二维横向微波色散关系以及波的传播形式。结果表明,二维水表面的横向微波具有和一维情况类似的结果,即具有波长短、传播速度小的特点,因而可以对入射到表面的激光束进行调制,为水下声信号检测奠定了理论基础。

位于弹性半空间上的理想流体层动力反应——平面SV波入射

根据弹性固体与理想流体动力学方程,导出了固-液介质交界面上波的透射与反射系数的理论公式,分析了平面SV波从弹性半空间入射到与理想流体层的交界面时,弹性半空间的弹性模量和密度,平面SV波的入射角和频率,以及流体的体积模量和密度对理想流体层动压力的影响。

三种介质耦联系统动力反应分析的显式有限元法及其应用

在笔者已建立的流体饱和多孔介质动力分析的显式有限元法的基础上 ,提出了可分析任意形状的流体饱和多孔介质 单相弹性固体介质 理想流体介质耦联的复杂系统的动力响应的显式有限元方法 .该方法建立的有限元方程列式具有解耦特征 ,不需求解联立方程组 ,因而极大地提高了计算效率 .将这一方法用于分析了考虑库水、坝、淤泥层和基岩这一复杂系统动力相互作用问题的斜坝面的地震响应 ,并给出了一些计算结果 .

理想流体柏努利方程在化工原理教学中的应用

在化工原理教学中,理想流体伯努利方程能够帮助学生理解流体的能量转换与守恒特性。本文提出了由理想流体到一般流体逐步导出伯努利方程的方法,给出了两种适合于不同层次教学需要的伯努利方程的推导过程,一种强调了数学的严格性和规范性,另一种旨在加深学生对能量守恒和流体运动过程的理解。

理想流体对流传热问题的理论解

研究理想流体受迫对流传热和自然对流传热问题的理论解。采用流体无垂直于壁面法线方向运动 (即无穿透 )的条件取代黏性流体在壁面无滑移条件 ,解决了流体在边界上有滑移时计算对流传热系数的困难 ,给出了理想流体与平壁受迫对流传热、理想流体与竖直壁面自然对流传热和理想流体在管内受迫对流传热的理论解。结果表明 :理想流体的对流传热与黏性流体同样存在着热边界层。在外部流动的情况下 ,无论受迫对流传热还是自然对流传热 ,对流传热系数都与流体的导热系数、密度和比热三者乘积的二分之一次方成正比。在管内受迫对流的情况下 ,当无因次长度大于 0 .0 5时 ,局部 N u和界面无因次温度分布都不再变化 ,对于恒热流边界条件 ,N u等于 8,截面无因次平均温度等于 2 ;对于恒壁温边界条件 ,N u等于 5 .782 ,截面无因次平均温度等于 2 .3 1

淤砂层模型对上层理想流体动力反应的影响——平面SV波入射

采用解析方法,分析了平面SV波斜入射时弹性半空间-淤砂层-理想流体层系统的动力反应,其中将淤砂层分别模拟为线弹性固体、黏弹性固体、理想流体和黏性流体等不同特性的介质,并与将淤砂层模拟为两相多孔介质的计算结果进行了比较。研究表明在平面SV波斜入射的情况下,当渗透系数很小时,多孔介质可以近似简化为黏弹性固体。