Archive issue - vol.3 No.3



   No.   Author(s) - Title
Pages

   1.
 

  -- 65-th Anniversary of Dr. Harmindar Singh Takhar
 

363-365
 

   2.
 

 Mohammadein A., El-Kabeir S.M., El-Hakiem M. A. and Gorla R.S.R -- Hiemenz flow of a micropolar fluid in hydromagnetics
 

367-376
 

   3.
 

 Hassanien I.A., Abdullah A.A. and Gorla R.S.R. -- Numerical solutions for heat transfer in a micropolar fluid over a stretching sheet
 

377-391
 

   4.
 

 Hossain M.A., Alim M.A. and Takhar H.S. -- Effect of radiation on mixed convection boundary layer flow along a vertical cylinder
 

393-404
 

   5.
 

 Drawal A., ¯aba S. and Kie³basa J. -- The analysis of the temperature-compensated anemometer
 

405-412
 

   6.
 

 Chen F.-K. -- A yield criterion for powdered metal compaction
 

413-432
 

   7.
 

 Özgüç A.F. -- Non-darcian effects on the heat-pipe wicking limit
 

433-450
 

   8.
 

 Kumari M. and Pop I. -- Free convection over a vertical rotating cone with constant wall heat flux
 

451-464
 

   9.
 

 Erdogan M.E. -- Unsteady flow of a viscous fluid due to an oscillating plane wall
 

465-478
 

   10.
 

 Kuznetsov A.V. -- Computer simulation of fluid flow and heat transfer in strip casting of aluminum alloys
 

479-490
 

   11.
 

 Devahastin S., Siow S.L. and Mujumdar A.S. -- Effect of inclination on free convective heat transfer during melting of a phase change material in a rectangular enclosure
 

491-515
 

   12.
 

 Tameroglu S. -- Analytical solution of a mixed boundary value problem for rectangular plates
 

517-530
 

 



2.

HIEMENZ FLOW OF A MICROPOLAR FLUID IN HYDROMAGNETICS

A. MOHAMMADEIN, S.M. EL-KABEIR, M.A. EL-HAKIEM

Mathematics Department, Faculty of Science
South Valley University, Aswan, EGYPT

R.S.R. GORLA
Department of Mechanical Engineering
Cleveland State University
Cleveland, Ohio 44115, USA

     A boundary layer analysis has been presented for Hiemenz flow in hydromagnetics of a micropolar incompressible, viscous, electrically conducting fluid impinging normal to a plane in the presence of a transverse magnetic field. Numerical solutions are given for the governing momentum and angular momentum equations. An approximate solution is given which is simple and yet sufficiently accurate for the entire range of values of Harman number investigated. A discussion has been provided for the effect micropolar parameters on Hiemenz flow in hydromagnetics.

Key words:

stagnation point flow, micropolar fluid, hydromagnetic flow.

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3.

NUMERICAL SOLUTIONS FOR HEAT TRANSFER IN
A MICROPOLAR FLUID OVER A STRETCHING SHEET

I.A. HASSANIEN

Department of Mathematics, Faculty of Science,
Assiut University,Assiut,Egypt.

A.A. ABDULLAH
Department of Mathemties, Faculty of Applied Sciences,
Umm-Al Qoura University,Saudi Arabia

R.S.R. GORLA
Department of Mechanical Eng. Dept.,
Cleveland State University Cleveland, Ohio 44115,U.S.A.

     The boundary layer flow and heat transfer from a stretching sheet to a microplar fluid are investigated. The governing equations for momentum, angular momentum and energy have been solved numerically by means of the Chebyshev spectral method. Numerical data for the friction factor and Nusselt number has been tabulated. Surface mass transfer and the power law constant for the wall temperature have considerable influence on the heat transfer rate.

Key words:

micropolar fluid, heat transfer, stretching sheet, numerical solution.

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4.

EFFECT OF RADIATION ON MIXED CONVECTION BOUNDARY
LAYER FLOW ALONG A VERTICAL CYLINDER

M. A. HOSSAIN, M. A. ALIM

Department of Mathematics, University of Dhaka
Dhaka 1000, BANGLADESH

H. S. TAKHAR
Manchester School of Engineering, University of Manchester
Manchester M13 9PL, U. K.

     Mixed convection flow of an optically dense viscous incompressible fluid along a vertical cylinder including the effects of radiation has been studied when the surface temperature is kept uniform. With appropriate transformations, the boundary layer equations governing the flow are reduced to local non-similarity equations. Solutions to the governing equations are obtained by employing an implicit finite difference method together with the Keller box scheme, as well the local non-similar method with a second order trunction, for values of the transverse curvature parameter, x, in the range [0,10]. Effects of the pertinant parameters, such as the radiation parameter, Rd, the surface temperature parameter, qw, and the buoyancy parameter W , taking Prandtl number, Pr, equal to 0.7, on the local skin-friction and the local Nusselt are explored in this stidy.

Key words:

Radiation, mixed convection, boundary layer flow.

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5.

THE ANALYSIS OF THE TEMPERATURE-COMPENSATED ANEMOMETER
Andrzej DRWAL, S³awomir ¯ABA

Laboratory of Electronics, Kraków
University of Technology
Kraków, POLAND

Jan KIE£BASA
Strata Mechanics Research Institute of the Polish
Academy of Sciences
Kraków, POLAND

     The paper presents a new method for temperature compensation in a hot-wire anemometer. This is a further development of the approach suggested by (Kie³basa, 1991), (Kie³basa and Ligêza, 1991) and (Ligêza, 1993) where the hot wire was connected in the bridge circuit supplied with linearly increasing voltage. In the branch opposite the hot wire there are two resistors so chosen that with the first of them the bridge will be zeroed while the wire is less heated, with the other resistor it will happen when the wire is heated more. Comparators connected to the resistors allow for measuring the currents flowing through the hot wire at the instants when the voltage across the measuring diagonal passes through zero. These two currents make it possible to determine flow velocity.

Key words:

hot-wire sensor, thermoanemometry, temperature compensation.

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6.

A YIELD CRITERION FOR POWDERED METAL COMPACTION

Fuh-Kuo CHEN

Department of Mechanical Engineering
National Taiwan University
Taipei, Taiwan, R.O.C.

     A yield criterion and the associated flow rule for the powdered metal compaction was proposed in the present study. In the proposed yield criterion, both the bulk movement and the consolidation of powdered metal in the compaction process were considered. In order to reflect the effect of volume change in the powder deformation, the first invariant of the stress tensor was added in the proposed yield criterion. Some previous yield criteria suggested for bulk materials were also evaluated in the present study to investigate the possible yield locus for the powder compaction. Material constants were introduced in the proposed yield criterion and the experimental procedures for the determination of these material constants were established. The states of stress predicted by the proposed yield criterion for the deformation of powder in the compaction process were compared with those obtained from the triaxial compaction test. The good agreement between the predicted values and the experimental results confirms the validity of the proposed yield criterion.

Key words:

compaction process, powdered metal, yield criterion.

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7.

NON-DARCIAN EFFECTS ON THE HEAT-PIPE WICKING LIMIT

A. Feridun ÖZGÜÇ

Istanbul Teknik Üniversitesi, Makina Fakültesi
80191-Gümüºsuyu, Istanbul, TURKEY

     This paper investigates the non-Darcian effects, i.e., the wall, the inertial, the variable porosity, and the interfacial shear effects, on the wicking limit of a heat-pipe. It is shown that the presence of the pipe wall reduces the liquid flow rate in the wick and results in a lower wicking limit than that predicted by Darcy's law. At high heat loads, the liquid velocity in the wick may reach a magnitude such that the inertial effect needs to be considered. This inertial effect, in general, brings the wicking limit further down. The vapor shear exerted on the wick flow can also significantly lower the wicking limit as the aspect ratio becomes smaller. For sintered-sphere wicks, the porosity variation near the wall results in flow channelling and, consequently, a greater wicking limit is attained. Parameters such as the Darcy number, the Reynolds number, and the aspect ratio are found significant for the prediction of the wicking limit.

Key words:

heat pipe, porous media, non-Darcian.

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8.

FREE CONVECTION OVER A VERTICAL ROTATING
CONE WITH CONSTANT WALL HEAT FLUX

Mahesh KUMARI

Department of Mathematics, Indian Institute of Science
Bangalore 560012, INDIA

Ioan POP
Faculty of Mathematics, University of Cluj
R-3400, Cluj, CP 253, ROMANIA

     This paper summarizes a numerical study of free convection flow over a vertical rotating cone in a quiescent fluid. A combined forced/free convection parameter is defined which allows the description of the entire regime from pure free convection to pure forced convection flow. The transformed equations are solved numerically for some values of the Prandtl number and the combined convection parameter using a very efficient finite-difference method. The effects of these parameters on the velocity and temperature fields as well as on the local skin friction and wall temperature distribution are illustrated. The results are compared with those from the literature. An excellent agreement is found.

Key words:

free convection, rotating cone, constant wall heat flux.

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9.

UNSTEADY FLOW OF A VISCOUS FLUID
DUE TO AN OSCILLATING PLANE WALL

M.Emin ERDOGAN

Instanbul Teknik Üniversitesi
Makina Fakültesi 80191 Gümüºsuyu
Istanbul, TURKEY

     The flow of a viscous fluid produced by a plane boundary moving in its own plane with a sinusoidal variation of velocity is considered. An analytical solution describing the flow at small and large times after the start of the boundary is obtained by the Laplace transform method. The solution confirms that the intuitive solution known in the literature, which for a long time steady periodic oscillation is set up with the same frequency as the velocity of the plane boundary, is correct. The solution gives not only the steady solution but also the transient solution. The time required to attain steady flow depends on the initial conditions. The time required for the cosine oscillation of the boundary is one-half cycle and it is a full cycle for the sine oscillation of the boundary. It is shown that the time required to attain the steady flow can also be obtained by the variation of the shear stress at the wall with time.

Key words:

viscous fluid, oscillating wall, unsteady flow.

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10.

COMPUTER SIMULATION OF FLUID FLOW AND HEAT
TRANSFER IN STRIP CASTING OF ALUMINUM ALLOYS

Andrey V. KUZNETSOV

Department of Mechanical and Aerospace Engineering
Noth Carolina State University,
Raleigh, NC 27695-7910, USA

     In this study, results of numerical analysis of the continuous casting process aimed for a production of thin aluminum-copper strips are reported. A characteristic feature of the continuous casting process considered in this paper is a strong forced convection of liquid alloy caused by a changing height of a free surface. Computations are performed for Al-4.5 wt pct Cu alloy. In this investigation, heat transfer process is coupled with the fluid flow which occurs in the liquid metal and in the mushy zone. It is shown that there is an essential forced convection flow in the upper part of mushy zone between the position where the liquidus line reaches the free surface and the position where the height of the free surface reaches its maximum. This flow can cause a destruction of the dendritic structure which in its turn can be one of the reasons for instability of the process.

Key words:

strip casting, heat and fluid flow, mathematical modelling.

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11.

EFFECT OF INCLINATION ON FREE CONVECTIVE
HEAT TRANSFER DURING MELTING OF A PHASE
CHANGE MATERIAL IN A RECTANGULAR ENCLOSURE
S. DEVAHASTIN, S.L. SIOW

Department of Chemical Engineering, McGill University
Montreal, Quebec, CANADA H3A 2B2

A.S. MUJUMDAR
Department of Chemical Engineering, McGill University
3480 Univesity St.Montreal,
Quebec, CANADA H3A 2A7

     Determination of heat transfer during melting in enclosures is important in the design of heat exchangers using phase change material (PCM) for thermal energy storage. Melting of the PCM generally invokes free convection currents in the melt phase depending on the orientation and geometry of the heat transfer surfaces. This paper deals with a computational investigation of the flow patterns and heat transfer rates which develop during the melting of a PCM contained in a rectangular chamber. Effects of heating both the vertical and horizontal faces as well as orientation of the cavity to the gravitational vector are examined. The shapes of the solid-liquid interface demonstrate clearly the generation of the cellular structure in the melt phase when the bottom horizontal face is heated. The cellular structure results in an undulating pattern for the heat transfer distribution on the bottom surface. The number of peaks and valleys in the Nusselt number distribution depends on the thickness of the melt layer.

Key words:

heat transfer, phase change material, rectangular enclosure.

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12.

ANALYTICAL SOLUTION OF A MIXED BOUNDARY
VALUE PROBLEM FOR RECTANGULAR PLATES

Sacit TAMEROGLU

Istanbul Technical University,
Faculty of Civil Engineering 80626,
Maslak, Istanbul, TURKEY

     In this work a theoretical analysis is presented for free vibrations and buckling of rectangular plates resting on an elastic foundation with three fixed and one hinged boundaries and subjected to uniform and constant compressive forces. The technique applied is based on the use of a non-orthogonal series expansions consisting of some specially chosen trigonometric functions for the deflection surface W of the plate.

Key words:

rectangular plate, vibration, buckling, Euler and Bernoulli polynomials.

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