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Mathematical model of micropolar fluid in two-phase immiscible fluid flow through porous channel

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Applied Mathematics and Mechanics(English Edition) 2018年第7期39卷 993-1006页

作者： P.K.YADAV s.JAIsWAL B.D.sHARMA Department of Mathematics Motilal Nehru National Institute of Technology Allahabad

This paper is concerned with the flow of two immiscible fluids through a porous horizontal channel. The fluid in the upper region is the micropolar fluid/the Eringen fluid, and the fluid in the lower region is the Newtonian viscous fluid. The flow is driven by a constant pressure gradient. The presence of micropolar fluids introduces additional rotational parameters. Also, the porous material considered in both regions has two different permeabilities. A direct method is used to obtain the analytical solu- tion of the concerned problem. In the present problem, the effects of the couple stress, the micropolarity parameter, the viscosity ratio, and the permeability on the velocity profile and the microrotational velocity are discussed. It is found that all the physical parameters play an important role in controlling the translational velocity profile and the microrotational velocity. In addition, numerical values of the different flow parameters are computed. The effects of the different flow parameters on the flow rate and the wall shear stress are also discussed graphically.

关键词： micropolar fluid immiscible fluid porous medium couple stress microp=olarity parameter

Numerical simulation of Vortex Engine Flow Field:One Phase and Two Phases

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Journal of Thermal science 2009年第3期18卷 226-234页

作者： A.F.Najafi s.D.saemi M.H.saidi Department of Energy Engineering Power and Water University of Technology Department of Mechanical Engineering Sharif University of Technology

Aiming at improving efficiency in combustion systems, the study on droplet behavior and its trajectory is of crucialimportance. Vortex engine is a kind of internal combustion engine which uses swirl flow to achieve highercombustion efficiency. One of the important advantages of designing vortex engine is to reduce the temperatureof walls by confining the combustion products in the inner vortex. The scopes of this investigation are to studyvortex engine flow field as well as effective parameters on fuel droplet behavior such as droplet diameter, dropletinitial velocity and inlet velocity of the flow field. The flow field is simulated using Reynolds stress TransportModel (RsM). The Eulerian-Lagrangian method and the one-way coupling approach are employed to simulatetwo phase flow and dispersed phase in the chamber, respectively. A new method, based on computing pressureforce exerted on the droplet surface, is introduced to determine the distinction between using one-way andtwo-way coupling approaches. The results showed that the droplets with smaller diameter are more likely to followthe flow stream lines than bigger droplets, thus evaporate completely in the chamber. Moreover, droplets withgreater initial velocity have higher evaporation rate, yielding the existence of evaporation and combustion in theinner vortex. Additionally, the higher inlet velocity of continuous phase results in higher centrifugal force, leadsdroplets in question to deviate towards the wall faster.

关键词： Vortex Engine swirl Flow Lagrangian Approach Fuel Droplet

Frictionally excited thermoelastic dynamic instability of functionally graded materials

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Acta Mechanica sinica 2019年第1期35卷 99-111,I0004页

作者： J.Liu L.L.Ke Y.s.Wang College of Engineering Huazhong Agricultural UniversityWuhan 430070China Institute of Engineering Mechanics Beijing JiaotongUniversity Beijing 100044China

The perturbation method is applied to investigate the frictionally excited thermoelastic dynamic instability (TEDI) of a functionally graded material (FGM) coating in half-plane sliding against a homogeneous half-plane. We assume that the thermoelastic properties of the FGM vary exponentially with thickness. We also examine the effects of the gradient index, sliding speed, and friction coefficient on the TEDI for various material combinations. The transverse normal stress for two different coating structures is calculated. Furthermore, the frictional sliding stability of two different coating structures is analyzed. The obtained results show that use of FGM coatings can improve the TEDI of this sliding system and reduce the possibility of interfacial failure by controlling the interfacial tensile stress.

关键词： Thermoelastic dynamic instability Frictional heat Functionally graded materials stress analysis

Hydromagnetic thin film flow of Casson fluid in non-Darcy porous medium with Joule dissipation and Navier＇s partial slip

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Applied Mathematics and Mechanics(English Edition) 2017年第11期38卷 1613-1626页

作者： G.s.sETH R.TRIPATHI M.K.MIsHRA Department of Applied Mathematics Indian Institute of Technology (India School of Mines) Dhanbad 826004 India

In this paper, the effects of viscous and Ohmic heating and heat genera- tion/absorption on magnetohydrodynamic flow of an electrically conducting Casson thin film fluid over an unsteady horizontal stretching sheet in a non-Darcy porous medium are investigated. The fluid is assumed to slip along the boundary of the sheet. similar- ity transformation is used to translate the governing partial differential equations into ordinary differential equations. A shooting technique in conjunction with the 4th order Runge-Kutta method is used to solve the transformed equations. Computations are car- ried out for velocity and temperature of the fluid thin film along with local skin friction coefficient and local Nusselt number for a range of values of pertinent flow parameters. It is observed that the Casson parameter has the ability to enhance free surface velocity and film thickness, whereas the Forchheimer parameter, which, is responsible for the inertial drag has an adverse effect on the fluid velocity inside the film. The velocity slip along the boundary tends to decrease the fluid velocity. This investigation has various applications in engineering and in practical problems such as very large scale integration （VLsI） of electronic chips and film coating.

关键词： fluid thin film non-Darcy medium velocity slip unsteady stretching sheet,Joule dissipation heat generation/absorption

EXACT sOLUTIONs FOR MAGNETOHYDRODYNAMIC FLOW IN A ROTATING FLUID

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Acta Mechanica sinica 2002年第3期18卷 244-251页

作者： s. Asghar Masood Khan A.M. siddiqui T. Hayat Department of Mathematics Quaid-i-Azam University Islamabad Pakistan Department of Mathematics Pennsylvania State University York Campus 1031 Edgecomb Avenue New York PA 17403 USA

An analytical solution is obtained for the flow due to solid-body rotations an oscillating porous disk and of a fluid at infinity. Neglecting the induced magnetic field, the effects of the transversely applied magnetic field on the flow are studied. Further, the flow confined between two disks is also discussed. It is found that an infinite number of solutions exist for the flow confined between two disks.

关键词： rotating fluid porous disk double disks magnetohydrodynamic flow

Influence of Zn^(2+)or Cu^(2+) on Reduction and Recalcination Behavior of Fe_2TiO_5

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Journal of Materials science & Technology 2007年第5期23卷 697-702页

作者： M.Bahgat M.H.Khedr H.s.Abdelmaksoud CMRDI P.O.Box 87-HelwanCairoEgypt Chemistry Department Faculty of ScienceBenisuef UniversityEgypt

Fe2O3, TiO2, CuO and ZnO powders were mixed according to the formula of （1-x）TiO2 xCuO-Fe2O3 or （1-x）TiO2 xZnO-Fe2O3 （x=0, 0.2 0.4, 0.6, 0.8, 1）, and well ball-milled with H2O for 3 h to ensure homogeneity of the powdered solids, then fired at 1200℃ for 4 h. The fired samples were reduced at 500℃ with hydrogen gas. The reduced samples were subjected to recalcination at 500℃ in CO2 atmosphere. Both of fired, reduced and calcined samples were characterized by X-ray diffraction, vibrating sample magnetometry, reflected light microscopy and scanning electron microscopy. Different phases were formed after firing of Cu^＋2 or Zn^2＋ substituted Fe2TiO5. Magnetization （Bs） of the formed phases after firing are very low corresponding to diluted magnetic semiconductors （DMs） and increases with increasing the substituted cations （Cu^＋2 or Zn^2＋）. The reduction of the fired samples enhanced the Bs values whereas the reducibility increases with increasing the Cu^＋2 or Zn^2＋ content. samples show different tendency toward CO2 decomposition which is very important for environmental minimization for CO2.

关键词： Nanosized ferrite Titanate Reduction Magnetic properties Reduction-recalcin-ation CO2 decomposition

Localized Corrosion Characteristics of Nickel Alloys： A Review

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Acta Metallurgica sinica(English Letters) 2017年第4期30卷 296-305页

作者： Helmuth sarmiento Klapper Natalia s. Zadorozne Raul B. Rebak Center for Materials Research Baker Hughes 29221 CelleGermany Instituto de Materiales de Misiones (IMAM) UNaMCONICET 3300 Posadas Argentina GE Global Research Schenectady NY 12309 USA

There are a great variety of commercial nickel alloys mainly because nickel is able to dissolve a large amount of alloying elements while maintaining a single ductile austenitic phase. Nickel alloys are generally designed for and used in highly aggressive environments, for example, those where stainless steels may experience pitting corrosion or environmentally assisted cracking. While nickel alloys are generally resistant to pitting corrosion in chloride-containing environments, they may be prone to crevice corrosion attack. Addition of chromium, molybdenum and tungsten increases the localized corrosion resistance of nickel alloys. This review on the resistance to localized corrosion of nickel alloys includes specific environments such as those present in oil and gas upstream operations, in the chemical process industry and in seawater service.

关键词： Nickel alloys Localized corrosion Oil and gas seawater Chemical process industry

Application of fuzzy logic for determining of coal mine mechanization

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Journal of Coal science & Engineering(China) 2012年第3期18卷 225-231页

作者： HOssEINI s AA ATAEI M HOssEINI s M AKHYANI M Department of mining Shahrood BranchIslamic Azad UniversityShahroodIran Faculty of Mining Petroleum and GeophysicsShahrood University of TechnologyShahroodIran

The fundamental task of mining engineers is to produce more coal at a given level of labour input and material costs, for optimum quality and maximum efficiency. To achieve these goals, it is necessary to automate and mechanize mining operations. Mechanization is an objective that can result in significant cost reduction and higher levels of profitability for underground mines. To analyze the potential of mechanization, some important factors such as seam inclination and thickness, geological disturbances, seam floor conditions and roof conditions should be considered. In this study we have used fuzzy logic, membership functions and created fuzzy rule-based methods and considered the ultimate objective： mechanization of mining. As a case study, the mechanization of the Tazare coal seams in shahroud area of Iran was investigated. The results show a low potential for mechanization in most of the Tazare coal seams.

关键词： fuzzy logic mechanization coal seams productivity fuzzytech software

Exact solution for the unsteady flow of a semi-infinite micropolar fluid

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Acta Mechanica sinica 2011年第3期27卷 354-359页

作者： H.H. sherief M.s. Faltas E.A. Ashmawy Department of Mathematics Faculty of ScienceAlexandria University

The unsteady motion of an incompressible micropolar fluid filling a half-space bounded by a horizontal infinite plate that started to move suddenly is considered. Laplace transform techniques are used. The solution in the Laplace transform domain is obtained by using a direct approach. The inverse Laplace transforms are obtained in an exact manner using the complex inversion formula of the transform together with contour integration techniques. The solution in the case of classical viscous fluids is recovered as a special case of this work when the micropolarity coecient is assumed to be zero. Numerical computations are carried out and represented graphically.

关键词： Unsteady motion . Laplace transform . Microp-olar fluid