Abstract: Mixed convection in two-dimensional shallow rectangular enclosure is considered. The top hot wall moves with constant velocity while the cold bottom wall has no motion. Simulations are performed for Richardson number ranging from Ri = 0.001 to 100 and for Reynolds number keeping fixed at Re = 408.21. Under these conditions cavity encompasses three regimes: dominating forced, mixed and free convection flow. The Prandtl number is set to 6 and the effects of cavity inclination on the flow and heat transfer are studied for different Richardson number. With increasing the inclination angle, interesting behavior of the flow and thermal fields are observed. The streamlines and isotherm plots and the variation of the Nusselt numbers on the hot wall are presented. The average Nusselt number is found to increase with cavity inclination for Ri ³ 1 . Also it is shown that the average Nusselt number changes mildly with the cavity inclination in the dominant forced convection regime but it increases considerably in the regime with dominant natural convection.
Abstract: This work deals with problems of tool axis inclination angles in ball-end milling. Tool axis inclination angle contributes to improvement of functional surface properties (surface integrity - surface roughness, residual stress, micro hardness, etc.), decreasing cutting forces and improving production. By milling with ball-end milling tool, using standard way of cutting, when work piece and cutting tool contain right angle, we have zero cutting speed on edge. At this point cutting tool only pushes material into the work piece. Here we can observe the following undesirable effects - chip contraction, increasing of cutting temperature, increasing vibrations or creation of built-up edge. These effects have negative results – low quality of surface and decreasing of tool life (in the worse case even it is pinching out). These effects can be eliminated with the tilt of cutting tool or tilt of work piece.
Abstract: The hidden-point bar method is useful in many
surveying applications. The method involves determining the
coordinates of a hidden point as a function of horizontal and vertical
angles measured to three fixed points on the bar. Using these
measurements, the procedure involves calculating the slant angles,
the distances from the station to the fixed points, the coordinates of
the fixed points, and then the coordinates of the hidden point. The
propagation of the measurement errors in this complex process has
not been fully investigated in the literature. This paper evaluates the
effect of the bar geometry on the position accuracy of the hidden
point which depends on the measurement errors of the horizontal and
vertical angles. The results are used to establish some guidelines
regarding the inclination angle of the bar and the location of the
observed points that provide the best accuracy.
Abstract: The Lattice Boltzmann Method (LBM) with double populations is applied to solve the steady-state laminar natural convective heat transfer in a triangular cavity filled with water. The bottom wall is heated, the vertical wall is cooled, and the inclined wall is kept adiabatic. The buoyancy effect was modeled by applying the Boussinesq approximation to the momentum equation. The fluid velocity is determined by D2Q9 LBM and the energy equation is discritized by D2Q4 LBM to compute the temperature field. Comparisons with previously published work are performed and found to be in excellent agreement. Numerical results are obtained for a wide range of parameters: the Rayleigh number from to and the inclination angle from 0° to 360°. Flow and thermal fields were exhibited by means of streamlines and isotherms. It is observed that inclination angle can be used as a relevant parameter to control heat transfer in right-angled triangular enclosures.
Abstract: Carbon Capture & Storage (CCS) is one of the various
methods that can be used to reduce the carbon footprint of the
energy sector. This paper focuses on the absorption of CO2 from
flue gas using packed columns, whose efficiency is highly dependent
on the structure of the liquid films within the column. To study the
characteristics of liquid films a CFD solver, OpenFOAM is utilised
to solve two-phase, isothermal film flow using the volume-of-fluid
(VOF) method. The model was validated using existing experimental
data and the Nusselt theory. It was found that smaller plate inclination
angles, with respect to the horizontal plane, resulted in larger wetted
areas on smooth plates. However, only a slight improvement in
the wetted area was observed. Simulations were also performed
using a ridged plate and it was observed that these surface textures
significantly increase the wetted area of the plate. This was mainly
attributed to the channelling effect of the ridges, which helped to
oppose the surface tension forces trying to minimise the surface area.
Rivulet formations on the ridged plate were also flattened out and
spread across a larger proportion of the plate width.
Abstract: A numerical analysis used to simulate the effects of wavy surfaces and thermal radiation on natural convection heat transfer boundary layer flow over an inclined wavy plate has been investigated. A simple coordinate transformation is employed to transform the complex wavy surface into a flat plate. The boundary layer equations and the boundary conditions are discretized by the finite difference scheme and solved numerically using the Gauss-Seidel algorithm with relaxation coefficient. Effects of the wavy geometry, the inclination angle of the wavy plate and the thermal radiation on the velocity profiles, temperature profiles and the local Nusselt number are presented and discussed in detail.
Abstract: In order to encourage the construction of green homes
(GH) in Malaysia, a simple and attainable framework for designing
and building GHs is needed. This can be achieved by aligning GH
principles against Cole-s 'Sustainable Building Criteria' (SBC). This
set of considerations was used to categorize the GH features of three
case studies from Malaysia. Although the categorization of building
features is useful at exploring the presence of sustainability
inclinations of each house, the overall impact of building features in
each of the five SBCs are unknown. Therefore, this paper explored
the possibility of quantifying the impact of building features
categorized in SBC1 – “Buildings will have to adapt to the new
environment and restore damaged ecology while mitigating resource
use" based on existing GH assessment tools and methods and other
literature. This process as reported in this paper could lead to a new
dimension in green home rating and assessment methods.
Abstract: Horizontal wells are proven to be better producers
because they can be extended for a long distance in the pay zone.
Engineers have the technical means to forecast the well productivity
for a given horizontal length. However, experiences have shown that
the actual production rate is often significantly less than that of
forecasted. It is a difficult task, if not impossible to identify the real
reason why a horizontal well is not producing what was forecasted.
Often the source of problem lies in the drilling of horizontal section
such as permeability reduction in the pay zone due to mud invasion
or snaky well patterns created during drilling. Although drillers aim
to drill a constant inclination hole in the pay zone, the more frequent
outcome is a sinusoidal wellbore trajectory. The two factors, which
play an important role in wellbore tortuosity, are the inclination and
side force at bit. A constant inclination horizontal well can only be
drilled if the bit face is maintained perpendicular to longitudinal axis
of bottom hole assembly (BHA) while keeping the side force nil at
the bit. This approach assumes that there exists no formation force at
bit. Hence, an appropriate BHA can be designed if bit side force and
bit tilt are determined accurately. The Artificial Neural Network
(ANN) is superior to existing analytical techniques. In this study, the
neural networks have been employed as a general approximation tool
for estimation of the bit side forces. A number of samples are
analyzed with ANN for parameters of bit side force and the results
are compared with exact analysis. Back Propagation Neural network
(BPN) is used to approximation of bit side forces. Resultant low
relative error value of the test indicates the usability of the BPN in
this area.
Abstract: A method based on the power series solution is proposed to solve the natural frequency of flapping vibration for the rotating inclined Euler beam with constant angular velocity. The vibration of the rotating beam is measured from the position of the corresponding steady state axial deformation. In this paper the governing equations for linear vibration of a rotating Euler beam are derived by the d'Alembert principle, the virtual work principle and the consistent linearization of the fully geometrically nonlinear beam theory in a rotating coordinate system. The governing equation for flapping vibration of the rotating inclined Euler beam is linear ordinary differential equation with variable coefficients and is solved by a power series with four independent coefficients. Substituting the power series solution into the corresponding boundary conditions at two end nodes of the rotating beam, a set of homogeneous equations can be obtained. The natural frequencies may be determined by solving the homogeneous equations using the bisection method. Numerical examples are studied to investigate the effect of inclination angle on the natural frequency of flapping vibration for rotating inclined Euler beams with different angular velocity and slenderness ratio.
Abstract: A numerical study on the turbulent flow and heat
transfer characteristics in the rectangular channel with different types
of baffles is carried out. The inclined baffles have the width of 19.8
cm, the square diamond type hole having one side length of 2.55 cm,
and the inclination angle of 5o. Reynolds number is varied between
23,000 and 57,000. The SST turbulence model is applied in the
calculation. The validity of the numerical results is examined by the
experimental data. The numerical results of the flow field depict that
the flow patterns around the different baffle type are entirely different
and these significantly affect the local heat transfer characteristics.
The heat transfer and friction factor characteristics are significantly
affected by the perforation density of the baffle plate. It is found that
the heat transfer enhancement of baffle type II (3 hole baffle) has the
best values.
Abstract: Vortex-shedding phenomenon of the flow
around combined two bodies having various geometries and sizes has been investigated experimentally in the Reynolds
number range between 4.1x103 and 1.75x104. To see the effect
of the rotation of the bodies on the vortex shedding, the
combined bodies were rotated from 0° to 180°. The combined models have a cross section composing of a main circular cylinder and an attached circular or square cylinder. Results
have shown that Strouhal numbers for two cases were
changed considerably with the angle of incidence, while it was found to be largely independent of Reynolds number at 150. Characteristics of the vortex formation region and
location of flow attachments, reattachments, and separations
were observed by means of the flow visualizations.
Depending on the inclination angle the effects of flow
attachment, separation and reattachment on vortex-shedding phenomenon have been discussed.
Abstract: An efficient transient flow simulation for gas
pipelines and networks is presented. The proposed transient flow
simulation is based on the transfer function models and MATLABSimulink.
The equivalent transfer functions of the nonlinear
governing equations are derived for different types of the boundary
conditions. Next, a MATLAB-Simulink library is developed and
proposed considering any boundary condition type. To verify the
accuracy and the computational efficiency of the proposed
simulation, the results obtained are compared with those of the
conventional finite difference schemes (such as TVD, method of
lines, and other finite difference implicit and explicit schemes). The
effects of the flow inertia and the pipeline inclination are
incorporated in this simulation. It is shown that the proposed
simulation has a sufficient accuracy and it is computationally more
efficient than the other methods.
Abstract: This study presents the improvement of thermal
performance of heat pipe using copper nanofluid with aqueous
solution of n-Butanol. The nanofluids kept in the suspension of
conventional fluids have the potential of superior heat transfer
capability than the conventional fluids due to their improved thermal
conductivity. In this work, the copper nanofluid which has a 40 nm
size with a concentration of 100 mg/lit is kept in the suspension of
the de-ionized (DI) water and an aqueous solution of n-Butanol and
these fluids are used as a working medium in the heat pipe. The study
discusses about the effect of heat pipe inclination, type of working
fluid and heat input on the thermal efficiency and thermal resistance.
The experimental results are evaluated in terms of its performance
metrics and are compared with that of DI water.
Abstract: Although many researchers have studied the flow
hydraulics in compound channels, there are still many complicated problems in determination of their flow rating curves. Many different
methods have been presented for these channels but extending them
for all types of compound channels with different geometrical and
hydraulic conditions is certainly difficult. In this study, by aid of nearly 400 laboratory and field data sets of geometry and flow rating
curves from 30 different straight compound sections and using artificial neural networks (ANNs), flow discharge in compound channels was estimated. 13 dimensionless input variables including relative depth, relative roughness, relative width, aspect ratio, bed
slope, main channel side slopes, flood plains side slopes and berm
inclination and one output variable (flow discharge), have been used
in ANNs. Comparison of ANNs model and traditional method
(divided channel method-DCM) shows high accuracy of ANNs model results. The results of Sensitivity analysis showed that the relative depth with 47.6 percent contribution, is the most effective input parameter for flow discharge prediction. Relative width and
relative roughness have 19.3 and 12.2 percent of importance, respectively. On the other hand, shape parameter, main channel and
flood plains side slopes with 2.1, 3.8 and 3.8 percent of contribution, have the least importance.
Abstract: As the Social network game(SNG) is rising
dramatically worldwide, an interesting aspect has appeared in the
demographic analysis. That is the ratio of the game users by gender.
Although the ratio of male and female users in online game was
60:40% previously, the ratio of male and female users in SNG stood at
47:53% which shows that the ratio of female users is higher than that
of male users. Here, it should be noted that 35% in those 53% female
users are the first-time users of game. This fact suggests that women
who were not interested in game previously has taken an interest in
SNG. Notwithstanding this issue, there have been little studies on the
female users of SNG although there are many studies that analyzed the
tendency of female users- online game play. This study conducted the
analyzed how the game-playing tendency of SNG gamers was
manifested in the game by gender. For that, this study will identify the
tendency of SNG users by gender based on the preceding studies that
analyzed the online game users by gender. The subject of this study
was confined to the farm and urban construction simulation games
which were offered based on the mobile application platform.
Regarding the methodology of study, the first focus group
interview(FGI) was conducted with the male and female users who
had played games on Social network service(SNS) until recently. Later,
the second one-on-one in-depth interview was conducted to gain an
insight into the psychological state of the subjects.
Abstract: The flow field around a flat plate of infinite span has
been investigated for several values of the angle of attack. Numerical
predictions have been compared to experimental measurements, in
order to examine the effect of turbulence model and grid resolution
on the resultant aerodynamic forces acting on the plate. Also the
influence of the free-stream turbulence intensity, at the entrance of
the computational domain, has been investigated. A full campaign of
simulations has been conducted for three inclination angles (9°, 15°
and 30°), in order to obtain some practical guidelines to be used for
the simulation of the flow field around inclined plates and discs.
Abstract: The paper provides a numerical investigation of the
entropy generation analysis due to natural convection in an inclined
square porous cavity. The coupled equations of mass, momentum,
energy and species conservation are solved using the Control Volume
Finite-Element Method. Effect of medium permeability and
inclination angle on entropy generation is analysed. It was found that
according to the Darcy number and the porous thermal Raleigh
number values, the entropy generation could be mainly due to heat
transfer or to fluid friction irreversibility and that entropy generation
reaches extremum values for specific inclination angles.
Abstract: In association with path dependence, researchers often
talk of institutional “lock-in", thereby indicating that far-reaching
path deviation or path departure are to be regarded as exceptional
cases. This article submits the alleged general inclination for stability
of path-dependent processes to a critical review. The different
reasons for path dependence found in the literature indicate that
different continuity-ensuring mechanisms are at work when people
talk about path dependence (“increasing returns", complementarity,
sequences etc.). As these mechanisms are susceptible to fundamental
change in different ways and to different degrees, the path
dependence concept alone is of only limited explanatory value. It is
therefore indispensable to identify the underlying continuity-ensuring
mechanism as well if a statement-s empirical value is to go beyond
the trivial, always true “history matters".
Abstract: This project focuses on the development of a line
follower algorithm for a Two Wheels Balancing Robot. In this
project, ATMEGA32 is chosen as the brain board controller to react
towards the data received from Balance Processor Chip on the
balance board to monitor the changes of the environment through
two infra-red distance sensor to solve the inclination angle problem.
Hence, the system will immediately restore to the set point (balance
position) through the implementation of internal PID algorithms at
the balance board. Application of infra-red light sensors with the PID
control is vital, in order to develop a smooth line follower robot. As a
result of combination between line follower program and internal self
balancing algorithms, we are able to develop a dynamically
stabilized balancing robot with line follower function.
Abstract: This work describes the aerodynamic characteristic for
aircraft wing model with and without bird feather like winglet. The
aerofoil used to construct the whole structure is NACA 653-218
Rectangular wing and this aerofoil has been used to compare the
result with previous research using winglet. The model of the
rectangular wing with bird feather like winglet has been fabricated
using polystyrene before design using CATIA P3 V5R13 software
and finally fabricated in wood. The experimental analysis for the
aerodynamic characteristic for rectangular wing without winglet,
wing with horizontal winglet and wing with 60 degree inclination
winglet for Reynolds number 1.66×105, 2.08×105 and 2.50×105 have
been carried out in open loop low speed wind tunnel at the
Aerodynamics laboratory in Universiti Putra Malaysia. The
experimental result shows 25-30 % reduction in drag coefficient and
10-20 % increase in lift coefficient by using bird feather like winglet
for angle of attack of 8 degree.