
Archive issue  vol.3 No.4
2.
VARIABLE VISCOSITY EFFECTS ON NATURAL CONVECTION
IN A MICROPOLAR FLUID AT AN AXISYMETRIC STAGNATION POINT
A. A. MOHAMMADEIN, S. M. ElKABEIR,
Mathematics Department,
Faculty of Science, South Valley University,
AswanEGYPT
Rama Subba Reddy GORLA,
Mechanical Engineering Department,
Cleveland State University,
Cleveland, Ohio 44115, USA
A threedimensional boundary layer solution is presented for the natural
convection in a micropolar fluid in the vicinity of an axisymmetric stagnation
point on heated vertical surfaces. The effects of variable viscosity are included.
The governing equations for the velocity, microrotation and temperature fields
are solved numerically.

Key words: 
natural convection, micropolar fluids, axisymmetric stagnation flow. 
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3.
MEASUREMENTS OF THE VELOCITY FIELD OF THE LAMINAR
BOUNDARY LAYER FOR WATER FREE CONVECTION ALONG
AN ISOTHERMAL VERTICAL FLAT PLATE
DeYi SHANG
Department of Fenous Metallurgy,
Northeastern University, Shenyang, CHINA.
BuXuan WANG
Department of Thermal Engineering,
Tsinghua University, Beijing, CHINA.
H.S. TAKHAR
Manchester School of Engineering,
University of Manchester,
Manchester, M13 9PL, U.K.
The velocity field of laminar free convection for water flowing past an
isothermal vertical flat plate is measured for different temperature conditions
using the laser Doppler velocimetry. In the experiment, the temperatures on the
vertical surface and in the ambient water are controlled at t_{w}=40^{o}C and t_{*}=20^{o}C and t_{w}=60^{o}C and t_{*}=20^{o}C,
respectively. The laser Doppler velocimeter is employed using a technique of
frequency deviation shift so that it can accurately measure a smaller velocity
field of a fluid, such as the velocity of water free convection. For each
temperature condition the velocity field w_{x} is measured at heights of 0.05, 0.10,
0.15, and 0.20m. For comparison of the measured results with calculated values,
corresponding numerical calculations considering variable thermophysical
properties are carried out. By the use of similarity variables, the numerical
solutions are transformed to the corresponding dimensionless values, and the
experimental data are transformed to the associated dimensionless velocities.
The experimental data and the numerical solutions of the velocity field are listed
in the tables and plotted in figures. A very good agreement between the measured
and calculated values is observed.

Key words: 
free convection, laminar boundary layer, laser Doppler velocimetry, vertical plate. 
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4.
NONLINEAR TRANSIENT ANALYSIS OF POINT RUB EFFECTS
IN A FLEXIBLE ROTOR
C.C. LEE,
Consulting Design Engineer
Solar Turbines, Inc.
SAN DIEGO, CA
P.E. ALLAIRE,
Wade Professor
Mechanical, Aerospace and Nuclear Engineering
University of Virginia
Charlottesville, VA 22901
Rubs occur in industrial rotating machinery in common practice. However, the
vibration spectrum produced by different rub conditions is very different and not
always easy to interpret. This paper presents a nonlinear analysis of a single
mass rotor subject to a point rub with dry friction (Coulomb damping) and compares
the results to experimental data. Experimentally, subsynchronous vibrations occur
at whirl ratios of 1/N(N=2,3,4...) relative to operating speed with shaft orbits of complicated
Lissajous shapes. These results have not been fully explained in the literature.
A point rub dry friction model is used, different from previous authors. The
nonlinear point rub transient analysis used numerical integration of the equations
of motion forward in time to determine the rotor response. The results obtained
matched the experimental results relatively well in terms of both whirl ratios of 1/N
and the Lissajous shapes. Shaft orbits were found to be a mix of forward and
backward precession, rather than the strictly backward whirl often cited in the
literature for rubs. Orbit frequency spectrums were found using a Fast Fourier
transform numerical algorithm. At the whirl ratio of 1/3, the analysis showed that
the rotor only hit the point rub during every two out of three shaft revolutions.
It was also found that the rub friction coefficient had little effect on the
nonlinear transient results for this rotor and rub model.

Key words: 
dry friction, nonlinear analysis, point rub, single mass rotor. 
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5.
EFFECTS OF LOWCALCIUM FLY ASH ON
THE RHEOLOGY OF FRESH CEMENT PASTES
Stefania GRZESZCZYK and Grzegorz LIPOWSKI
Technical University of Opole,
45233 Opole, ul. St. Mikolajczyka 5, POLAND
Results of the effect of fly ash upon rheological properties of cement pastes
have been presented. Bituminous fly ash when added to cement have been found to
produce a decrease both in the yield shear stress value and plastic viscosity of
cement pastes the greater the higher the fly ash content. A relation between the
fine fraction share in the fly ash and the flowability degree of cement pastes was
found. The fine fraction content of the fly ash has been proved to be a better
parameter to evaluate the influence of the fineness upon the rheology of cement
pastes than Blain's specific surface area is.

Key words: 
rheology, cement paste, fly ash. 
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6.
EVALUATION OF INTERLAMINAR SHEAR STRESSES
IN A FIBERREINFORCED LAMINATED BEAM BY THE IFRM THEORY
Michio KURASHIGE and Kazunari YAMAMOTO
Iwate University,
Department of Mechanical Engineering
Ueda 435, Morioka 0208551, JAPAN
Kazumi WATANABE
Yamagata University,
Department of Mechanical Engineering
Johnan 4316, Yonezawa 992, JAPAN
By using the linear IFRM theory, interlaminar shear stresses are estimated for
a fiberreinforced laminated beam subjected to a line force. The analysis for this
estimation is fully threedimensional. The beam has three layers. Its core is
reinforced in the width direction, whereas its skins in the longitudinal direction.
The skins are also assumed to have infinitesimal thickness for the sake of
analytical simplicity. In spite of this assumption, inextensibility of the skin
layers is valid, since the IFRM theory postulates that the materials are
completely inextensible in fiber directions. The analytical results explain very
well the observations of delamination shapes and justify applicability of various
beam theories to the theoretical analysis of the observations in beam impact tests
by use of a line nose impactor. It is also shown that the IFRM theory can explain
the observed slight deviation of the delamination from the interface at its early
stage.

Key words: 
IFRM theory, fiberreinforced beam, interlaminar shear stress, impact test, delamination 
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7.
TWO COLLINEAR GRIFFITH CRACKS IN
AN ORTHOTROPIC STRIP WITH PUNCHES
P.C. SINGH
Department of Mathematics
College of Textile Technology
Serampore  712201, W.B. INDIA
B. PATRA
Department of Mathematics
Bengal Engineering College (D.U.)
Howrah  711 103, W.B. INDIA
T.N. MAULIK
Technical Teachers Training Institute
BlockFC, SectorIII
Salt Like City, Calcutta  700091, W.B. INDIA
Integral transform technique is employed to solve the elastodynamic problem of
steadystate propagation of two symmetrically situated identical collinear
Griffith cracks along the mid plane of orthotropic strip of finite thickness 2h
with centrally situated moving punches along the boundaries of the layer. The
problem is reduced to the solution to a pair of simultaneous singular integral
equations with Cauchy type singularities which have finally been solved through
finite Hilbert transform technique. For large h, analytical expressions for the
local stress field near the crack tip and the stress intensity factors are
obtained. Graphical plots of the numerical results are also presented.

Key words: 
Griffith crack, punch, singular integral equation, stress intensity factor, orthotropic material, Yoffe model, Mach number, subsonic propagation, local stress field. 
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8.
NUMERICAL COMPUTATION OF VISCOUS FLOW
FIELD PAST CIRCULAR CYLINDER
Gorachand LAYEK
Physics and Applied Mathematics Unit
Indian Statistical Institute
203, B. T. Road, Calcutta700 035, India
Incompressible viscous flow past a circular cylinder has been studied
numerically in this work, under laminar conditions. A controlvolume based
finitedifference scheme in a staggered grid has been used to solve unsteady
NavierStokes equations in bodyfitted orthogonal coordinates. The farfield
boundary has been mapped into a finite one. The pressure Poisson equation and
pressurevelocity correction formulae have been derived. The convergence value
achieves the level of 0.5*10^{5} after a few iterations. It is noted that secondary eddies
appear periodically at higher Reynolds numbers. The results are compared with
available experimental data and it is found that important quantities like
Strouhal numbers, drag coefficients and separation angles match well with
established values.

Key words: 
Staggered grid, secondary eddy, pressure Poison equation, pressurevelocity corrections. 
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9.
MODELLING OF SOLUTE MIGRATION AND
ITS ADSORPTION IN POROUS LAYERS
S. WROŃSKI, E. MOLGA, L. RUDNIAK and R. HUBACZ
Department of Chemical and Process Engineering,
Warsaw University of Technology
ul. Waryńskiego 1, 00645 Warszawa, POLAND
The immobilization of pollutants by irreversible sorption in agglomerates
immersed directly into the porous layer has been considered. A general model for
migration and sorption of soluble contaminants in a porous layer has been
formulated and the method of its solution has been proposed. The calculations have
been carried out to display the model effectiveness and flexibility. The influence
of the size of agglomerates, the density and geometry of their distribution on the
decontamination efficiency has been studied. Also the effect of mass transfer
parameters on this efficiency has been investigated.

Key words: 
soil decontamination, sorption agglomerates, migration of pollutants 
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10.
HOTWIRE ANEMOMETER WITH THE MODULATED OVERHEATING RATIO
 AN INSTRUMENT FOR MEASURING NONISOTHERMAL FLOWS
Jan KIEŁBASA
Strata Mechanics Research Institute
Polish Academy of Sciences  CRACOW
The paper presents the method for simultaneous measurements of flow velocity
and the temperature of the medium, using a single wire probe operating in a
constanttemperature system wherein the overheating ratio undergoes sine
modulations. Theoretical bases for these measurements are presented here together
with some examples of velocity and temperature distribution patterns in the
temperature and velocity wake formed behind the hot wire used to provide a test
environment for the proposed scheme.

Key words: 
hotwire anemometer, nonisothermal flow, velocity and temperature measurement 
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