Journal of Engineering

In this study, a different design of passive air Solar Chimney(SC)was tested by installing it in the south wall of insulated test room in Baghdad city. The SC was designed from vertical and inclined parts connected serially together, the vertical SC (first part) has a single pass and Thermal Energy Storage Box Collector (TESB (refined paraffin wax as Phase Change Material(PCM)-Copper Foam Matrix(CFM))), while the inclined SC was designed in single pass, double passes and double pass with TESB (semi refined paraffin wax with copper foam matrix) with selective working angle ((30o, 45o and 60o). A computational model was employed and solved by Finite Volume Method (FVM) to simulate the air induced through the test room by SC effect. The governing equation of Computational Fluid Dynamic (CFD) model was developed by the effective heat capacity method equation to describe the heat storage and release from PCM-CFM. Practical and computational Results referred to increase in thermal conductivity of the paraffin wax that supported by CFM than 10 times, while the ventilation effect is still active for hours after sun set amount. The maximum ventilation mass flow rate with TESB collector was 36.651 kg/hr., when the overall discharge coefficient equals 0.371. Also, the experimental results referred to the best working angle range 45~60o, while the highest approaching temperature (between air and collector) was appeared for the double passes flat plate collector. Results gave higher heat storage efficiency 47% when the maximum solar radiation 780 W/m2 at 12.00 pm, and the energy summation through duration of charging time was 18460 kJ. Double passes SC at 60o angle presented the highest efficiency with value approaching to 73%, while TESB collector efficiency depicted highest efficiency value 70% at 12:00 pm.

In this study, the effect of intersecting ribs with inclined ribs on the heat transfer and flow
characteristics of a high aspect ratio duct has been numerically investigated. The Relative
roughness pitch (P/e) is 10 and the Reynolds number range from 35,700 to 72,800. ANSYS
(Fluent-Workbench 18.0) software has been utilized to solve the Reynolds averaged Navier-Stokes
(RANS) equations with the Standard k-ε turbulence model. Three ribbed models have been used
in this study. Model 1 which is a just inclined ribs, Model 2 which has a single longitudinal rib at
the center with inclined ribs and Model 3 which has two longitudinal ribs at the sides. The results
showed that the heat transfer rate has been enhanced when the intersecting ribs are used. Model 3
has achieved the highest overall thermal performance. The increasing in Nusselt number ratio
(???????? / ???????????? ) for Model 3 and 2, relative to Model 1, are 13.19% and 7.03%, respectively.
Consequently, the hybridizing by intersecting ribs with inclined ribs is considered as an
advantageous technique to enhance the heat transfer.

This study aims to model the flank wear prediction equation in metal cutting, depending on
the workpiece material properties and almost cutting conditions. A new method of energy
transferred solution between the cutting tool and workpiece was introduced through the flow
stress of chip formation by using the Johnson-Cook model. To investigate this model, an
orthogonal cutting test coupled with finite element analysis was carried out to solve this model
and finding a wear coefficient of cutting 6061-T6 aluminum and the given carbide tool

Many problems were encountered during the drilling operations in Zubair oilfield. Stuckpipe, wellbore instability, breakouts and washouts, which increased the critical limits problems, were observed in many wells in this field, therefore an extra non-productive time added to the total drilling time, which will lead to an extra cost spent. A 1D Mechanical Earth Model (1D MEM) was built to suggest many solutions to such types of problems. An overpressured zone is noticed and an alternative mud weigh window is predicted depending on the results of the 1D MEM. Results of this study are diagnosed and wellbore instability problems are predicted in an efficient way using the 1D MEM. Suitable alternative solutions are presented ahead to the drilling process commences in the future operations.

Modified bentonite has been used as effective sorbent material for the removal of acidic dye
(methyl orange) from aqueous solution in batch system. The natural bentonite has been modified
using cationic surfactant (cetyltrimethyl ammonium bromide) in order to obtain an efficient
sorbent through converting the properties of bentonite from hydrophilic to organophilic. The
characteristics of the natural and modified bentonite were examined through several analyses such
as Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and
Surface area. The batch study was provided the maximum dye removal efficiency of 88.75 % with
a sorption capacity of 555.56 mg/g at specified conditions (150 min, pH= 2, 250 rpm, and 0.5
g/100 ml). The-results-showed that with the Freundlich isotherm model the sorption data was
accurately described with (R2≥0.94) in comparison with the Langmuir model under the studied
conditions. The kinetic studies were revealed that the sorption follows a pseudo-second-order
kinetic model which indicates chemisorption between sorbent and sorbate molecules

Wellbore stability is considered as one of the most challenges during drilling wells due to the
reactivity of shale with drilling fluids. During drilling wells in North Rumaila, Tanuma shale is
represented as one of the most abnormal formations. Sloughing, caving, and cementing problems
as a result of the drilling fluid interaction with the formation are considered as the most important
problem during drilling wells. In this study, an attempt to solve this problem was done, by
improving the shale stability by adding additives to the drilling fluid. Water-based mud (WBM)
and polymer mud were used with different additives. Three concentrations 0.5, 1, 5 and 10 wt. %
for five types of additives (CaCl2, NaCl, Na2SiO3, KCl, and Flodrill PAM 1040) was used.
Different periods of immersion (1, 24 and 72 hours) were applied. The results of the immersion
test showed that using 10 wt. % of Na2SiO3 for WBM gives a high recovery percentage (77.99 %)
after 72 hr, while the result of the dispersion test (roller oven) of 10 wt % of sodium silicate with
WBM was (80.97 %) after 16 hr. Also, the immersion test result of 10 wt% of sodium silicate
with polymer mud was (79.76 %) after 72 hr and the results of dispersion test (roller oven) of 10
wt. % of sodium silicate with polymer mud was (84.51 %) after 16 hr.

Highly plastic soils exhibit unfavorited properties upon saturation, which produce different
defects in engineering structures. Attempts were made by researchers to proffer solutions to these
defects by experimenting in practical ways. This included various materials that could possibly
improve the soil engineering properties and reduce environmental hazards. This paper investigates
the strength behavior of highly plastic clay stabilized with brick dust. The brick dust contents were
10%, 20%, and 30% by dry weight of soil. A series of linear shrinkage and unconfined
compression tests were carried out to study the effect of brick dust on the quantitative amount of
shrinkage experienced by highly plastic clay and the undrained shear strength. The effect of curing
on soil shear strength was included in this paper. It was found that the critical behavior of highly
plastic soil can be mitigated by mixing with 20% or 30% of brick dust. The undrained shear
strength of highly plastic clay mixed with brick dust increased with the increase of brick dust
content up to 20%. It was affected by the curing period. The best improvement was achieved when
the optimum content of brick dust was 20%. Finally, seven days of curing improved the undrained
shear strength with over 100%.

The main aim of this paper is studied the punching shear and behavior of reinforced concrete
slabs exposed to fires, the possibility of punching shear failure occurred as a result of the fires
and their inability to withstand the loads. Simulation by finite element analysis is made to predict
the type of failure, distribution temperature through the thickness of the slabs, deformation and
punching strength. Nonlinear finite element transient thermal-structural analysis at fire
conditions are analyzed by ANSYS package. The validity of the modeling is performed for the
mechanical and thermal properties of materials from earlier works from literature to decrease the
uncertainties in data used in the analysis. A parametric study was adopted in this study, it has
many factors such as the ratios of length to thickness, fire temperature, time exposed to fire,
concrete compressive strength, area exposed to fires and type of support. It can be
concluded from this research the significant factors that affect the punching shear strength.
However, the increasing ratio of length to thickness may be lead to increasing the deflection
more than 123% at fire condition. Also, the increasing temperature leads to increasing the
deflection about 40% at fire condition.

Stone Matrix Asphalt (SMA) is a gap-graded asphalt concrete hot blend combining high-quality
coarse aggregate with a rich asphalt cement content. This blend generates a stable paving
combination with a powerful stone-on-stone skeleton that offers excellent durability and routing
strength. The objectives of this work are: Studying the durability performance of stone matrix asphalt
(SMA) mixture in terms of moisture damage and temperature susceptibility and Discovering the
effect of stabilized additive (Fly Ash ) on the performance of stone matrix asphalt (SMA) mixture. In
this investigation, the durability of stone matrix asphalt concrete was assessed in terms of
temperature susceptibility, resistance to moisture damage, and sensitivity to the variation in asphalt
content. Specimens of 63.5 mm height and 102 mm diameter were compacted using the Marshall
method at 150 °C. The optimum asphalt content was determined. Additional specimens were
prepared with (0.5) percent below and above the OAC requirement. Specimens were subjected to
indirect tensile strength (ITS) determination at (25 and 40) °C, and double punch shear strength
determination. Another group of specimens was subjected to Marshall properties determination and
to moisture damage. It was observed that stone matrix asphalt exhibit lower sensitivity to the change
in asphalt content from the resistance to moisture damage and temperature susceptibility points of
view. However, the tensile and shear properties exhibit significant sensitivity to the variation in
asphalt content.

In this study, simply supported reinforced concrete (RC) beams were analyzed using the
Extended Finite Element Method (XFEM). This is a powerful method that is used for the
treatment of discontinuities resulting from the fracture process and crack propagation in
concrete. The mesoscale is used in modeling concrete as a two-phasic material of coarse
aggregate and cement mortar. Air voids in the cement paste will also be modeled. The coarse
aggregate used in the casting of these beams is a rounded aggregate consisting of different
maximum sizes. The maximum size is 25 mm in the first model, and in the second model, the
maximum size is 20 mm. The compressive strength used in these beams is equal to 26 MPa.
The subjects of this study are two RC beams subjected to a two-point loading designed to fail
due to flexure. The RC beams under loading were studied in the laboratory as well as
numerically. ABAQUS program was used for modeling and analyzing the RC beams. The
mesoscale modeling that was used to model the concrete required used a special program using
different programs but has not used the ABAQUS program directly. The result of the comparison
between the numerical and experimental showed that the mesoscale numerical model gave
results that were more approximate to the experimental ones, and the mesoscale modeling of
reinforced concrete is most convenient when the maximum size of aggregate is decreased

Piled raft is commonly used as foundation for high rise buildings. The design concept of piled
raft foundation is to minimize the number of piles, and to utilize the entire bearing capacity. High
axial stresses are therefore, concentrated at the region of connection between the piles and raft.
Recently, an alternative technique is proposed to disconnect the piles from the raft in a so called
unconnected piled raft (UCPR) foundation, in which a compacted soil layer (cushion) beneath the
raft, is usually introduced. The piles of the new system are considered as reinforcement members
for the subsoil rather than as structural members. In the current study, the behavior of unconnected
piled rafts systems has been studied numerically by means of 3D Finite Element analysis via
ABAQUS software. The numerical analysis was carried out to investigate the effect of thickness
and stiffness of the cushion, pile length, stiffness of foundation soil, and stiffness of bearing soil
on the performance of the unconnected piled raft. The results indicate that when unconnected piles
are used, the axial stress along the pile is significantly reduced e.g. the axial stress at head of
unconnected pile is decreased by 37.8% compared with that related to connected pile. It is also
found that the stiffness and thickness of the cushion, and stiffness of foundation soil have
considerable role on reduction the settlement.

The main objectives of this study were investigating the effects of the maximum size of coarse
Attapulgite aggregate and micro steel fiber content on fresh and some mechanical properties of
steel fibers reinforced lightweight self-compacting concrete (SFLWSCC). Two series of mixes
were used depending on maximum aggregate size (12.5 and 19) mm, for each series three
different steel fibers content were used (0.5 %, 1%, and 1.5%). To evaluate the fresh properties,
tests of slump flow, T500 mm, V funnel time, and J ring were carried out. Tests of compressive
strength, splitting tensile strength, flexural tensile strength, and calculated equilibrium density
were done to evaluate mechanical properties. For reference mixes, the results showed that mixes
with a larger maximum aggregate size of 19 mm exhibited better fresh properties, while
mechanical properties negatively affected by using a larger maximum aggregate size. The results
also showed that using steel fibers led to negative effects on fresh properties, especially with
higher steel fibers content and larger maximum aggregate size. The marginal effect of steel fibers
on compressive strength was noticed, while for both splitting and flexural tensile strength,
significant increase was obtained with increasing of steel fibers content. The properties of
SFLWSCC in the fresh state had a considerable effect on mechanical properties, whereas with
the best fresh properties, the best mechanical properties can be obtained.

The hydrodynamics behavior of gas - solid fluidized beds is complex and it should be analyzed
and understood due to its importance in the design and operating of the units. The effect of column
inside diameter and static bed height on the minimum fluidization velocity, minimum bubbling
velocity, fluidization index, minimum slugging velocity and slug index have been studied
experimentally and theoretically for three cylindrical columns of 0.0762, 0.15 and 0.18 m inside
diameters and 0.05, 0.07 and 0.09 m static bed heights .The experimental results showed that the
minimum fluidization and bubbling velocities had a direct relation with column diameter and static
bed height .The minimum slugging velocity had an inverse relation with static bed height and a
direct one with column diameter .There was no agreement between the experimental and calculated
values of Umb for Di=0.0762m ,this was a result to the assumption used in the correlation
development. The fluidization index values were around 1 in all cases and that proved that the
material is of Geldart type B. There was not a significant dependence of fluidization index and slug
index on static bed height and column diameter

Drilling fluid properties and formulation play a fundamental role in drilling operations. The Classical
water-based muds prepared from only the Syrian clay and water without any additives((Organic and
industrial polymers) are generally poor in performance. Moreover, The high quantity of Syrian clay
(120 gr / l) used in preparing drilling fluids. It leads to a decrease in the drilling speed and thus an
increase in the time required to complete the drilling of the well. As a result, the total cost of drilling
the well increased, as a result of an increase in the concentration of the solid part in the drilling fluid.
In this context, our study focuses on the investigation of the improvement in drilling mud Prepared
from the Syrian clay by reducing the clay concentration to (50 gr / L). And compensate for the
remaining amount (70 gr / l) of clay by adding (natural and industrial polymers) The rheological
properties and filtration are measured at different concentrations of polymers .. In light of the
experiments, we determine the polymers' concentrations that gave good results in improving the flow
properties and controlling the Filter. It is polymers that have given good results:
،HEC ،HEC and Xanthan Gum PAC and HEC ،CMCHV ،PolyAcryl Amid ،Xanthan Gum