Iraqi journal of mechanical and material engineering

Numerical Analysis of Unsteady Natural convection in square cavity filled with a
porous media studied in this paper. The left vertical wall preserves the constant high
temperature Th , and the right wall preserves the constant low temperature Tc and
both the horizontal walls are insulated . The alternating –direction implicit method (
A.D.I ) is used to solve the non-dimensional governing equations, and finite
differences method devoted to Nussele numbers and the horizontal and vertical
velocity flow . The results are obtained for the initial transient start up to the steady
state, and for Rayleigh number(
2 4 10 < Ra < 10 ). It is observed that the results for
average Nusselt number showing an undershoot during the transient period and that
the time required to reach the steady state is longer for low Rayleigh number and
shorter for high Rayleigh number.

A numerical investigation is adopted for a two dimensional thermal energy storage
system (TES), employing finite element method to compute the time of charging or
discharging energy from a phase change material (PCM) during day or night to utilize
it in free cooling of space applying Baghdad Summer climate conditions (ambient
temperature). A computer program is developed to analyze the thermal energy unit for
different tube diameters, air flow rates and inlet air temperature for both solidification
and melting processes. This study shows that utilizing small tube diameter, low flow
rates or air inlet temperature near the fusion temperature lead to increase time of
phase change process. It was also shown that the time duration of melting is larger
than solidification.

This research deals with the to study organic inhibitor as aqueous extracts of some
parts tree (palm) as corrosion inhibitor to protect low carbon steel in different
environments [Tap Water and Hydrochloric Acid (1M)] .
Several tests were conducted to evaluate the performance of inhibitor, using weight
loss method at different concentrations volume (0.5, 1.5, 3)% by volume. Inhibitor
efficiency in tap water and HCl at (3)% concentration of inhibitor reached to (81)%
and (92)% respectively.
Another test have been carried out to evaluate the corrosion rate by determination of
corrosion current by polarization method, where inhibitor efficiency reached to
82.72% in tap water and 89.56% in acidic solution when used (3)% by volume
inhibitor.
Finally microscope examination tests showed that, the inhibitor is not only active to
commercially corrosion inhibitors, but has greatly improved properties such as: low
cost, high efficiency and the important properties is easily apply, non-toxic and
nonpolluting of the environment.

The heat transfer from two dimensional unsteady state of composite straight extended
surfaces heat sink of different materials is analyzed here by using finite element
technique. Galerkin method with linear rectangular elements is used in the present
analysis. The effects of conductivity ratio (KR) on the efficiency and the effectiveness
of the heat sink are examined ( the efficiency & the effectiveness of the heat sink are
increased with increasing of (KR), also the present and non-present of the heat
generation through the heat sink is discussed. The effect of the conductivity ratio on
the steady state time is discussed here. It can be noted that the increasing of the
conductivity ratio (from less than one to greater than one) will reduce the time for
reach the steady sate.

Epoxy resins are widely used in industry by virtue of combinations of favorable
characteristics including good mechanical and physical properties, ease of processing
and low cost. However, these resins suffer from the disadvantage of brittleness, which
limits their use in many applications.
In this work, polymeric composites were prepared from epoxy resin reinforced Bidirectionally
(0o - 90o) by jute and glass fibers singly and in combination as a hybrid.
A comparison is made between the elastic modulus, material toughness and fracture
toughness of the composites with those of un-reinforced epoxy to find out the effect
of reinforcement on the composites at varying temperatures (0, 25, 40, and 60 Co).
Volume fraction for each reinforcement fibers (glass or jute) was 30% but for hybrid
composite was (15% glass fibers and 15% jute fibers).
The results show that the jute- reinforced laminates have much better properties than
the resin alone; but the properties are inferior to those of glass reinforced epoxy. The
most appropriate role for the jute fibers is, to use them as filler fibers in combination
with glass fibers to get moderate and acceptable mechanical properties during
applications. The improvements in mechanical properties (elasticity modulus, material
toughness, and fracture toughness) are 623%, 565%, and 593% respectively in
comparison with un-reinforced epoxy samples.

The interface is crucial in controlling composite properties because load is transferred
from the matrix to the fiber through this interface. In this paper a study of interface of
a composite material which consists of polymer matrix ( Epoxy ) reinforced with high
carbon steel wires, ( SRP ). This reinforcement offers high strength and stiffness
characteristic at a reasonable cost. Also, the effect of roughness of steel wire on
interface and mechanical properties are studied. The bonding force of ( SRP )
composite material with roughened surface increased by about (% 73.3) an increment
of flexural capacity by (11.77 %) and the impact energy is increased (60 %) as
compared with SRP with polished steel reinforcement wire.

The objective of the current research is to investigate the developing laminar flow of a
Newtonian incompressible fluid and heat transfer in the entrance region of a two
parallel plate channel were investigated. The continuity, x-momentum, and energy
equations were solved as a steady state in two dimension equations. The
dimensionless technique was used. These equations have been represented by finite
difference technique. This model has been solved by using the new method of implicit
scheme, which would minimize the solution errors. The velocity profile becomes fully
developed at approximately
L 2a 0.05 Re
e
=
, and the temperature distribution
becomes fully developed at approximately L 2a 0.05 Re .Pr
et
= , as expected. The
computational algorithm is able to calculate all the hydrodynamic properties such as
velocities. Also the computational algorithm is able to predict all the thermal
properties such as the temperature, bulk temperature, and local Nusselt number. The
validity of thermal results for constant wall temperature and constant wall heat flux is
verified and shows that there is a good agreement between the results of the present
numerical solution and the correlation related to it

The study concern with the measurement of hydraulic radius of imported porous
polymer disc of known values (0.8, 1)μm, using specific permeability and porosity
data.
The study started with the design and built up a permeability unit, with a sample cell
specified for this purpose. The followed by leak test and calibration.
Volumetric flow rate as a function of pressure difference, across the sample under
test, were measured.
The slope of the measured values (Q, }p) at the linear limit, was applied to calculate
the mean hydraulic radius; with respect to the air viscosity value, width and Area of
the sample. The compared data gives a limit of accuracy in the range of (12 – 16)%.