Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : CFD


CFD investigation of the erosion severity in 3D flow elbow during crude Oil contaminated sand transportation

M.A. Al-Baghdadi; K. K. Resan; M. Al-Waily

Engineering and Technology Journal, 2017, Volume 35, Issue 9, Pages 930-935

During upstream petroleum production operations, crude oil and sand eroded from formation zones are often transported as a mixture through pipes up to the well heads and between well heads and flow stations. The sand particles are carried by the flow momentum in streamlines that impinge the pipe walls, in particular at the elbows, resulting in seriously erosive damages. This can lead to a disastrous and costly failure in the system. Therefore, computing of erosion rate during the system operation is indispensable for predicting any potential failure in advance, and hence avoid it. Among all the fittings employed in piping systems, elbows are the most likely subjected to erosion resulting from sand particles carried with oil, where those particles deviate from the mainstream and impact the walls while passing through the bended section of elbows. To reduce the erosive damage produced by the solid particles, a numerical simulation based erosion prediction model has been employed to compute the relative erosion severity. In this study ,the potentials required to simulate the current problem comprehensively, various physical aspects have been combined together including flow turbulence, particle tracking, and erosion simulation. In addition to the comprehensive insights offered by the computational simulation of crude oil flow, high costs along with tedious efforts required for traditional experimentations can be avoided. The current analysis offers priceless physical insight towards serve this model as an alternative sand management tool, and can be used to quantify oil recovery. Furthermore, it can identify limiting steps and components; form a computer-aided tool for designing and optimizing the future pipe systems in order to enhance their lifetime through improving their erosion resistance, which is definitely will save considerable amount of time and cost.

Numerical Study of the Effects of Aneurysm and Stenosis in the Left Coronary Artery on the Human Blood Stream

A.A. Al-allaq; N. S. Mahmoud

Engineering and Technology Journal, 2017, Volume 35, Issue 1, Pages 29-40

The heart is the most important muscular organ in human's body, which pumps blood through the arteries to supply the body with oxygen and nutrients. The heart is supplied by the coronary blood vessel; therefore, the effect of aneurysm and stenosis in left coronary artery on the velocity of blood, wall shear stress of artery and mass flow rate of blood have been investigated in this study. The simulation program (ANSYS Fluent) was used to execute the numerical study. Typical geometry of left coronary artery and physiological parameters of human blood values were obtained from measured values reported in literature. The problem of the effect of the aneurysm and stenosis on the human blood stream has been solved numerically under three conditions, healthy artery and two infected cases (30%, 50%) percentage of aneurysm in left main stem (LMS) and stenosis in left anterior descending (LAD). It has been shown, in stenosis region that the velocity of blood will suffer fast flowing and an increase in the shear stress on the artery wall, in contrast with the aneurysm case, blood velocity becomes slow and low wall shear stress. Also irregularity was shown in mass flow rate of blood in the left coronary artery which suffers from aneurysm and stenosis compared with healthy artery.

Numerical Investigation on the Performance of an External Compression Supersonic Air Intake Using By-Pass Technique

Jalal M. Jalil; Abdullateef A. Jadallah; Ahmed F. Mahdi

Engineering and Technology Journal, 2013, Volume 31, Issue 6, Pages 1011-1025

Two-dimensional, supersonic flow field computation with by-pass holes has been conducted using Euler equation. An algorithm based on finite difference McCormack's technique is used to solve the subsonic-supersonic flow problem with and without by-passing. Trials on by-pass locations were also made. Operation without bypass shows the movement of the normal shock wave upstream which refers to an off-design operating regime. At a distance of 1.271 m measured from the cowl lip, the region of normal shock wave was localized near the throat which approximately represents the on-design perform 0ance condition (cells 8-9). When the flow is bypassed from the rear passages, the normal shock wave is sucked inside the flow passage save poor performance. Results show that by-passing provides a fast reaction to maintain a steady performance which meets the requirements of on-design operation. The Mach number variation corresponding to each case is presented. Results show that the tendency to unity Mach number near the cowl lip sector can be achieved using by-pass expelled. The influence of by-pass on the total pressure recovery and relative pressure is also discussed.

Study on Wind Loads Coefficients and Flow Field Characteristics Around the Parabolic Trough With Stiffeners

Mauwafak Ali.Tawfik; Bahaa.Ibrahim.Kazem; Haider.Hussein.Hamad

Engineering and Technology Journal, 2012, Volume 30, Issue 18, Pages 3280-3296

In the current study, the numerical analysis of the flow field characteristics around
the parabolic trough with stiffener of solar polar concentrating power system is
performed. The presence of stiffener changes the velocity and pressure distribution
around the trough and then the wind loads also changed. Wind loads (drag, lift and
moment) coefficients for different wind speeds and angles of attack are simulated.
Pressure distribution, velocity distribution and turbulent kinetic energy for different
wind speeds and angles of attack are also simulated. To verify the numerical
simulation, comparisons with experimental results are performed. Reproducing of
experimental boundary condition is carried out in numerical simulations. The
numerical simulations are performed by using computational fluid dynamics (CFD)
package fluent 12.1. The results of this simulation show that the flow field
characteristics are strongly related to angles of attack and trough orientation. Also the
most important result of this study is that the presence of stiffener makes the trough a
more bluff body than the trough without stiffener. This development of trough
configuration will excite more vortexes shedding around the edges of trough

Numerical Study of a Solar Chimney Power Plant

Rafah A. Najim; Jalal M. Jalil

Engineering and Technology Journal, 2012, Volume 30, Issue 15, Pages 2597-2608

Axi-symmetric, steady, incompressible, turbulent flow field developed by natural convection inside power plant solar chimney is investigated numerically using finite volume method. Navier-Stockes with energy equation is solved to achieve velocity components and temperature distribution inside solar chimney. To complete the thermal analysis, conduction through upper glass wall, chimney concrete wall and floor ground were investigated to calculate temperature distribution through theses walls. A standard turbulence model associated with lawss of the wall along solid boundaries was used. Special arrangement for mesh was used to deal with complicated shape of the domain. The main studied parameters are solar collector diameter, kinds of ground, periphery heights and solar intensity radiation. This study was compared with previous available experimental study and there is acceptable agreement. The performance of the solar chimney was examined through maximum air velocity in the tower inlet and maximum temperature in the ground floor. The final optimization parameters are defined within studied ranges.

Numerical Study for Natural Convection within a Rotating Cubic Enclosure

Hussein Majeed Salih

Engineering and Technology Journal, 2012, Volume 30, Issue 16, Pages 2792-2810

A numerical study of three–dimensional, steady, turbulent and incompressible
natural convection of air (Pr=0.72) within a rotating cubic enclosure is presented. The
present code is based on solving partial differential equations for conservation of
mass, momentum and energy equations for a rotating frame. The turbulence effect is
introduced by using two equations turbulence model of k-e . Finite volume method is
used in solving the governing equations. SIMPLE algorithm is applied to solve the set
discretization equations. To verify the validity of present method, present results is
compared with those of previous published work under the same conditions. The
influence of changing rotation Rayleigh number (Rar ) as a result of chancing
angular velocity of enclosure, and temperature difference of enclosure walls on the
average Nusselt number (Nu) is presented and correlated.

Study of Three Dimensional Fluid Flow inManifold-Laterals System

Jafar M. Hassan; Wahid S. Mohammad; Ayad F. Hameed

Engineering and Technology Journal, 2012, Volume 30, Issue 7, Pages 1132-1148

A three dimensional numerical simulation of fluid flow in a manifold-laterals system was carried out; several geometrical changes were made to study the effect on water flowing inside the manifold. The manifold hydraulic diameter and the length were kept constant in the study. The geometrical changes include the distance between laterals, the length of the laterals, and the laterals size. It is found that for Reynolds
Number (100 and 1000), increasing the length of the laterals gives uniform flow profile at laterals outlet. Also reducing lateral size will create a similar effect. A good agreement was found between the present and FLUENT6.2 results for mass flow rate from laterals.

Experimental and Numeriacal Study of Moisture Moviment Inside an Air Conditioned Space

Wahid S. Mohammad; Omar M. Mohamme

Engineering and Technology Journal, 2012, Volume 30, Issue 3, Pages 398-415

This research is concerned with a computational study to simulate a turbulent three
–dimensional buoyancy recirculation flow in an air-conditioned space. The study
includes the simulation of heat and moisture generated from an internal source inside the
space. An experimental facility to study temperature and moisture distribution in an airconditioned
space has also been designed, constructed and tested in a laboratory scale. A
numerical procedure was carried out to solve the elliptic partial differential equations that
govern the flow, heat and mass transfer in a finite –volume form. The finite -volume
approach was applied to solve these equations using the upwind –differencing scheme.
The SIMPLE iterative procedure [1] for solving the algebraic equations is employed in
the present study. The proposed method is the line by line technique uses the Tri-
Diagonal Matrix Algorithm (TDMA) as its basic unit. A modified version of a threedimensional
elliptic computer code was used to simulate heat and moisture transfer
generated from the internal source inside the space. A study of the flow, heat and mass
transfer in air-conditioned space are used as test cases to justify the performance of the
computational procedure. The temperature and moisture distribution were compared with
predictions of previous researchers. The data from the experimental model was also used
to verify the computational procedure predictions.

Three Dimensional Simulation of Supersonic Flow over Missiles of Different Shapes

Jalal M. Jalil; Hussain H. Al-Kayiem; Ahmed Kadhim Hussein

Engineering and Technology Journal, 2012, Volume 30, Issue 3, Pages 325-343

In this work, a three-dimensional primitive variable of supersonic flow over
missiles was computed based on finite difference computational fluid dynamic
methods. The problem was considered is to deal with external, inviscid, compressible
supersonic- flow over three-dimensional missiles with and without canard. Euler
equations were solved using time-marching MacCormack’s explicit technique. The
flow conditions are taken at sea level and Mach number was tested up to 4.0. To deal
with complex shape of missiles the so-called “body fitted coordinate system” was
considered and the algebraic and elliptic methods were used to generate grids over
missiles. The number of iterations and the number of mesh points depending on
Mach number. The result indicate, that for the same Mach number, the increasing of
mesh points, lead to increase of the number of iterations

Shock Wave Capturing Numerically in Two Dimensional Supersonic Wind Tunnel for Different Configuration

Ahmed Fouad Mahdi

Engineering and Technology Journal, 2012, Volume 30, Issue 3, Pages 426-442

Numerical solutions of two dimensional Euler equations are obtained for
transonic and supersonic flows. The shock capturing method is employed to solve
compressible Euler equations by using MacCormack's time marching method that
an explicit finite-difference technique. The test case chosen is that of a transonic
and supersonic flow through a channel with a circular arc bump on the lower wall,
half wedge and extended compression corner. Computational results accurately
reproduced the flow field. In three cases, contour plots showing the important
features of the flow-field are presented. The algorithm is tested for steady-state
inviscid flows at different Mach numbers ranging from the transonic to the supersonic
regime and the results are compared with the existing numerical solutions. The
method incorporates bounded high resolution of discontinuities and is therefore well
suited to all flow regimes ranging from transonic to supersonic.

A Numerical Prediction of the Turbulence Parameters in Two-Dimensional Ventilated Rooms

Ayad M. Salman

Engineering and Technology Journal, 2011, Volume 29, Issue 6, Pages 1052-1068

Turbulent flow in two-dimensional ventilated room has been numerically
simulated in the present research. A modified form of Wilcox's two-equation LRN
k-w model is proposed for predicting internal turbulent ventilation flows. The
modifications include adding a turbulent cross-diffusion term in the w-equation,
and re-establishing the closure constants and damping functions, with the
application of the wall-function method. The turbulent cross-diffusion for specific
rate, w, is modeled with two parts: a second-order diffusion term and a first-order
cross-diffusion term.
The air was used as the working fluid, and the length of ventilation enclosure (9
m), and height of ventilation enclosure (3 m). The study was made for Reynolds
number values of (Re=7.5´103).
A finite volume method is used with a staggered grid arrangement. The
continuity, momentum and turbulence model equations are solved with hybrid
method by using SIMPLE algorithm. A computer program in FORTRAN (90) was
developed to carry on the numerical solution. The Computational algorithm is
capable of calculating the hydrodynamic and turbulence properties such as the
velocity, and turbulent kinetic energy, specific dissipation rate (w), turbulent
Reynolds stress, and terms of convection, production, diffusion, destruction,
turbulent cross-diffusion and square root mean of fluctuating velocity. The results
showed the peak value of velocity near the wall jet region and negative value of
velocity near the bottom region (floor region) i.e. recirculating zone. The
maximum value of turbulent kinetic energy near wall jet region in the first
horizontal section of ventilation enclosure, and the profile become flattened in the
second section of ventilation enclosure room. The same behavior in the turbulent
Reynolds stress distribution because depending on velocity in his calculations. The
same behavior between production term and destruction term but the values of
production term is positive and the value of destruction term is negative. The
distribution approximately symmetry.
The numerical results were compared with other previous theoretical results.
The agreement was good, confirming the reliability of the proposed mathematical
model and computational algorithm in investigating the performance of turbulence
model in numerical simulation of turbulent ventilation flows.

Three-Dimensional Flow Model for The Downstream of Kuffa Barrage

Majid H. Hobi; Saleh I. Khassaf; Muhannad J. M. Al-Kizwini

Engineering and Technology Journal, 2011, Volume 29, Issue 3, Pages 434-441

The three-dimensional numerical computational fluid dynamics “CFD”
computer program "SSIIM" was used to predict the flow field downstream the
Kuffa Barrage. It solved the Reynolds-Averaged Navier–Stokes equations in three
dimensions to compute the water flow and used the finite-volume method as the
discretization scheme. The model was based on a three dimensional, nonorthogonal,
structured grid with a non-staggered variable placement. The
comparison between filed measurements and numerical results were considered to
make the correct decision in this model. The results showed that the maximum
velocities were inclined from the river center. The determination coefficients for
distribution of velocities ranged from 0.94 to 0.96.

Control of Separation For NACA 2412 Airfoil At Different Angles of Attack Using Air Blowing

Jalal M. Jalil; Assim H. Yousif; Yasser Ahmed Mahmood

Engineering and Technology Journal, 2010, Volume 28, Issue 16, Pages 5138-5150

The study of the separation control using the jet blowing based on the
computation of Reynolds-average Navier-Stocks equations is carried out in this work. A numerical model based on collocated Finite Volume Method is developed to solve the governing equations on a body-fitted grid, to compute the performance of airfoil by using the blowing jet. Above of all, the performance of turbulence model is investigation. A revised k-ƒÖ model is proposed as the known turbulence models perform well in reproducing the flow of airfoil at pre-stall or stall angle of attack. The systematical investigation of the jet blowing is conducted
on the NACA 2412 airfoil in the range of attack angle from 0o to 30o included up and beyond the stall angle at range of Re=3.4*105-1.7*106 . The influence of some parameters associated with using jet blowing, such as its location, and the speed ratio (Uj/U) strength on the performance of the NACA 2412 airfoil has also been studied. The result shows that the jet blowing is effective in controlling the separation at 0.3C and Uj/U=2. The large separation regions cannot be completely
removed by the jet blowing. However, the flow structure can be regularized. The lift coefficient of the control airfoil is also increased with the angle of the attack. The experimental results are obtained on airfoil NACA 2412 at 0.3C blowing and Uj/U=2, the results are been good agreement with the computational results.

Numerical Study of Solidification in Cavity with the Presence of Natural Convection

Wahid S. Mohammad

Engineering and Technology Journal, 2010, Volume 28, Issue 6, Pages 1160-1168

A study of Laminar two dimensional transient solidification with time –
dependent natural convection in the melt is carried out. The mathematical model
for the numerical simulation is based on enthalpy porosity method. The governing
equations are descritized on a fixed grid by means of a finite volume technique.
The (SIMPLE) procedure was adopted to solve mass, momentum and energy
equations for pure phase change material (water) placed in a cooled rectangular
cavity. The cavity was cooled from top alone, right side wall alone, and right side
wall with top and bottom walls together. In the case of top cooling a parabolic
shaped pattern of ice water interface was formed. For the right side wall cooling
the effect of density changes has led to an abnormal flow circulation which has
moderately modified the heat balance of the freezing interface causing a colliding
of cool and warm fluid layers. A density variation was seen in the freezing
interface region in most of the cases. The results obtained show good agreement
with experimental and numerical results of other researchers for pure convection
with small discrepancies in the ice interface. These discrepancies may be
attributed to the physical modeling used for water freezing.

Buoyancy Heat Transfer In Staggered Dividing Square Enclosure

Ali L. Ekaid; Ayad F. Hameed; Ahmad F. Mehde

Engineering and Technology Journal, 2010, Volume 28, Issue 4, Pages 639-663

In this research, the Buoyancy heat transfer and flow patterns in a partially
divided square enclosure with staggered partitions have been studied numerically.
The partitions were distributed on the lower and upper surfaces of the box in
staggered manner. The height of the partitions was varied. The conduction heat
transfer through the fins (partitions) was also included. It is assumed that the
vertical walls of enclosure were adiabatic and its horizontal walls were maintained
at uniform but in different temperature. The problem was formulated in terms of
the stream function-vorticity procedure. The numerical solution based on the
transformation of the governing equations by using finite difference method was
obtained. The effect of increasing the partition height and Rayleigh number on
contour maps of the stream lines and temperature were reported and discussed. In
addition, the research presented and discussed the results of the average Nussult
number of the enclosures heated wall at various Rayleigh number and
dimensionless partition heights. The results showed that the mean Nussult number
increases with the increasing of Rayleigh number and decreases with the
increasing of partition heights. The distributed heat by conduction through the
partition increases with the increasing of the partition height especially at
(H/L ≥ 0.3). A comparison between the obtained results and the published
computational studies has been made and it showed a good agreement with
percentage error not exceed (0.54%).

Numerical Study Of Turbulent Natural Convection In An Enclosure With Localized Heating From Left Side

Ali L. Ekaid

Engineering and Technology Journal, 2009, Volume 27, Issue 14, Pages 2692-2710

In this work, a numerical study is performed to predict the solution of buoyancy turbulent flow and heat transfer inside a square cavity with localized heating from the left side wall. Full Navier Stockes and energy equations were solved using Finite volume method with a non-uniform staggered grid. The studied Rayleigh numbers were
ranged between 1E108 to 1E1012 and Pr=0.72. For the purpose of the analysis, the heated dimensionless length L/H is varied from 0.2 to 0.8. The k-ε model with standard wall function is used to treat the turbulence in the flow. The obtained results show that the strength of the induced recirculating velocity is increased with the increase of Ra. Also the results displaced that the average Nu is increased with the increase of Ra. However the average Nu number is decreased with increasing of dimensionless heated length

Numerical Simulation of a Two-Dimension Ramp Inlet Flow Field

Jalal M. Jalil; Ahmed F. Kridy

Engineering and Technology Journal, 2009, Volume 27, Issue 6, Pages 1118-1126

The Two-dimension ramp inlet flow field was studied with typical mode operations.
Euler equations were used for solution with no special treatment required. In this work a
solution algorithm based on finite difference MacCormack’s technique was developed to
solve mixed subsonic-supersonic flow problem through the external shock diffusers
(ramp inlet) and it is found to be converge for supercritical and critical inlet operation.