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Go to Editorial ManagerA new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
Mixed convection heat transfer of air in a horizontal channel with an open square cavity is studied numerically. At the center of the cavity, it is an insulated rotating circular cylinder for enhancing the efficiency of heat transmission, the location of the inner cylinder is changed vertically along the centerline of the cavity. Heat is applied to the bottom wall of the cavity at a constant temperature, and the other walls are adiabatic. The flow is steady-state, laminar, and incompressible. Using computational fluid dynamics (CFD) and the commercial software program FLUENT 2019 R1, the equations of continuity, momentum, and energy are numerically solved. The angular velocity of the cylinder range is (0 . 5 ≤ ω ≤ 4) rad/sec in a counterclockwise direction, the Richardson number range ( Ri = 0 . 1 , 1 , 10), Reynolds number is 100 and the cylinder location is ( C = 70 , 50 , 30) mm. The airflow Prandtl number is taken as ( Pr = 0 . 7). The effect of various positions of the rotating cylinder has been examined through the visualization of streamline and isotherm contour, as well as the distribution of the average Nusselt number of the heated surface. The results indicate that the flow field and temperature distributions inside the cavity are strongly dependent on the rotating circular cylinder and the position of the inner cylinder.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
In this paper the conjugate heat transfer in rectangular channel is numerically investigated, where the effect of both axial heat conduction and entrance region on the internal forced convection in rectangular channels are studied. With decreasing the dimensions of channels the thickness of walls become large and in order of the channels dimensions as in microchannels. As a results the heat conduction in the walls especially in the axial direction can not be ignored, since it lead to decrease in the efficiency of heat transfer process. Also the effect of entrance region is taken into consideration where the flow is assumed developing hydro dynamically and thermally. A finite volume method is used to numerically solve the conjugate heat transfer in both the fluid and wall simultaneously. The results obtained shows that the existing of axial heat conduction lead to reduction in the heat transfer and it's effect increased with increasing the thickness of walls and Reynolds number. In this paper a correlation has been developed to calculate the value of axial heat conduction in channel's walls based on most of the affecting parameters. This correlation can be used accurately to compute the value of axial conduction in rectangular channels.
This study investigated the performance of symmetric airfoils of type NACA0012 numerically under different operating conditions. It has been assumed that the study involves steady state, non-compressive, and turbulent flows. The operating fluid was air. The effect of Reynolds number and angle of attack on lift and drag coefficients, pressure distribution, and velocity distribution was investigated. ANSYS FLUENT has been used to solve the numerical model by using continuity equations, Navier-Stokes equations, and the appropriate K-ω SST perturbation model. This study shows a clear difference between the pressure coefficient of the lower and upper surfaces of the airfoil at high Reynolds numbers, indicating higher lift at high Reynolds numbers. As the maximum stall angle of the airfoil NACA0012 is 14° after which it decreases significantly, a direct relationship was observed between lift and drag coefficients and angle of attack.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
The efficiency of an airfoil can be improved by adjusting its surface. CFD software was used to investigate a 2D airfoil with and without a spanwise semicircular groove on the upper surface. NACA0012 airfoils with and without grooves were analyzed using the k-ω turbulence model. The lift and drag coefficients were used to compared. To investigate the effect of groove location on airfoil efficiency, a groove was added in various locations and compared to a smooth airfoil. The flow velocity remained constant at 20 m/s at all angles of attack (AOA). According to this study, which used ANSYS software to simulate it numerically, the presence of a semicircular groove affects the aerodynamics of the airfoil, resulting in an improved efficiency coefficient of lift, which has risen by 2.25 percent, while the drag coefficient has decreased by 4.32 percent.
An incompressible three dimensional continuity and Navier-Stokes (momentum equations) equations are numerically solved to obtain the pressure drop and fluid friction in laminar steady state micro-channel flow of water. The governing equations are solved by using SIMPLE algorithm with finite volume method and FORTRAN code to obtain pressure field in rectangular micro-channel and then from the pressure field both friction factor f and friction constant Cf are obtained. The results showed that the factors affecting the pressure drop, friction factor f and friction constant Cf are; channel length L, Reynolds number Re, aspect ratio a, channel volume Vch and hydraulic diameter Dh. Increasing of channel length L leads to increase each pressure drop, f and Cf. On other hand, increasing of Re leads to increase pressure drop and decrease the f, while the Cf increase with low value of Re (Re less than 50) and then nearby with approximately constant value. Moreover, increasing of a, Vch and Dh separately leads to decrease pressure drop and increase both f and Cf.
Due to the significance of structural sandwiches with hexagonal cores, utilized in various applications including aerospace, marine industries, and rail transport, and their design that imparts superior strength compared to conventional forms. In this paper, fracture behavior of these structural sandwiches was examined. Initially, the equivalent modulus of elasticity was empirically determined for many cell side lengths, utilizing the stress-strain relationship derived from tensile tests on hexagonal specimens. The fracture behavior was analyzed numerically using Abaqus software. The core and the complete sandwich structure were examined under various loads, including tensile and shear forces. The influence of the hexagonal cell dimensions on the fracture modules and the stress intensity factor (SIF), was assessed. It was observed that when the cell thickness remains constant while the side length varies, the SIF increases with the increasing in side length. This leads to the influence of stiffness, where it decreases with the increase in side length of the cell core. For instance, when the side length is 10, the stress intensity factor is 4.821, while when the side length is 20, the stress intensity factor becomes 22.35. A relationship was found between the stress intensity factor and thickness, similar to the tension case. However, here, a relationship between (kl) and the (a/tc) ratio was established.
This study numerically investigates natural convection of Cu-water nanofluid in a square cavity subjected to a cooling air stream along the left wall, with the right and bottom walls maintained at cold (TC) and hot (TH) temperatures, respectively, while the top wall is adiabatic. The nanofluid flow is assumed laminar and governed by the Boussinesq approximation. The governing equations are solved using the finite volume method in ANSYS FLUENT. Simulations are performed for nanofluid volume fractions (φ = 0–0.16), Rayleigh numbers (Ra = 10³–10⁵), and free stream Reynolds numbers (Re∞ = 10³–10⁴). The effects of these parameters on stream function (ψ), temperature contours (θ), and average Nusselt number (Nuavg) are analyzed. Results indicate that heat transfer rates increase with higher φ, Ra, and Re∞. Increasing φ and Ra enhances circulation within the cavity, whereas higher Re∞ induces secondary vortices and reduces circulation in the primary vortex. Comparisons of local Nusselt numbers and temperature distributions with previous studies show good agreement, with maximum errors of 14.28% and 3.2%, respectively.
The dual synchronization of two different pairs of chaotic oscillators: one pair of Duffing oscillators and one pair of Murali-Lakshmanan-Chua (ML-Chua) circuits has been achieved by numerical simulations. The cross-coupling method, where the difference in the voltage between the sum of the two master oscillators' voltages and one of the slave oscillator voltages is injected 10 the other slave oscillator as an electrical current, for the dual synchronization has been used. The accuracy of synchronization of chaos is numerically obtained by calculating the root mean square error (RMSE). A communication scheme is presented, utilizing the chaotic masking (CMS) technique. Encoding and decoding of a message based on dual synchronization of chaos has been demonstrated.
A numerical study of mixed convection inside a horizontal channel with an open square cavity that includes an adiabatic rotating cylinder. The bottom wall of the cavity is heated at a constant temperature, and the remaining walls are adiabatic. The flow is incompressible, laminar and steady state. The equations of continuity, momentum and energy are solved numerically using computational fluid dynamics (CFD) with the commercial software package FLUENT 2019 R1. Reynolds number values of 50, 100 and 150, the Richardson number (0.1 ≤ Ri ≤ 10) and the angular velocity ( ω ) of cylinder is (0.5 ≤ ω ≤ 4) rad/sec with direction counter clockwise. Prandtl number for air flow is ( Pr = 0.7). The results are presented in terms of streamlines, isotherms, and the average Nusselt value is given over the heated bottom cavity. The combined effects of natural and forced convection in and out of the cavity were obtained. The results showed that at low Richardson values, Ri = 0.1 the effect of buoyancy force is neglected. The effect of increasing the cylinder speed is clearly noticeable at low Reynolds values, Re = 50. Average Nusselt values increase with increasing rotational speed of the cylinder for all Richardson values.
The conjugate natural convection-conduction heat transfer in a domain composed of nanofluids filled porous cavity heated by a vertical solid wall is studied under steady-state conditions. The vertical left wall of the solid is kept isothermal at hot temperature Th. The vertical right wall of the solid is in contact with the nanofluid saturated porous medium contained in the cavity. The right vertical wall of the cavity is kept isothermally at the lower temperature Tc. The upper and lower horizontal walls are kept adiabatic. The governing equations of the heat transfer in the solid wall and heat and nanofluid flow, based on the Darcy model, in the nanofluid-saturated porous medium together with the derived relation of the interface temperature are solved numerically using the over-successive relaxation finite- difference method. A temperature independent nanofluids properties model is adopted. The investigated parameters are the nanoparticles volume fraction (0-0.2), Rayleigh number Ra (10-1000), solid wall to base-fluid saturated porous medium thermal conductivity ratio kwf (0.1, 1, 10), and the solid wall thickness D (0.05-0.5). The results are presented in the conventional form; contours of streamlines and isotherms and the average Nusselt number. At a very low Rayleigh number Ra=10, an enhancement in heat transfer within the porous cavity with is observed. Otherwise, the heat transfer may be unchanged or deteriorated with depending on the wall thickness D and the conductivity ratio kwf.
This study investigates the deep drawing process of carbon fiber-reinforced high-density polyethylene (CF-HDPE) composites through experimental and numerical approaches. The experimental part involved fabricating CF-HDPE sheets and conducting deep drawing operations under controlled parameters (punch speed, temperature, and forming depth) to evaluate material behavior and mechanical properties. Numerically, finite element analysis (FEA) using ABAQUS simulated the forming process, analyzing stress distribution, strain development, and material deformation under varying conditions. Results revealed that increasing forming depth and decreasing forming temperature elevated the required forming force. Comparisons between experimental and numerical outcomes showed consistent trends, though some differences arose due to factors like friction and material nonlinearity. The findings contribute to optimizing deep drawing processes for composite materials, enhancing manufacturing precision, and minimizing material defects.
The surge tank is one of important control devices in reducing water Hummer effect on distributed network piping system and hydropower stations. An experimental study was conducted into a simple surge tank of 0.044 m in a diameter with upstream constant head reservoir of a height, 0.881 m and a water transporting pipe of a size 0.0202 m. Results indicate that rapid closure of a downstream valve causes under-damped stable oscillation in a surge tank. Experimental response agreed well with theoretical results when friction factor is considered to be variable, but with 85 % increases in settle time and more oscillations when constant friction factor is recognized at initial value before valve closure. Doubling surge tank area does not improve the dynamics properties; otherwise, Thoma area must be avoided for small sizes. Comsol multiphysics software 3.5 is used to deal with the dynamics of the surge tank numerically.
Hydrodynamics and heat transfer in a fully developed laminar incompressible reciprocating channel flow subjected to a constant heat flux have 'been investigated analytically using similarity transfo1mat ion. An exact analytical solution for the velocity, local, and bulk temperature as well as the Nusselt number has been obtained. The effect of the parameters Pr, Ao, y, and X/Dh on u, T, Tt, Nux, and Nux are presented. The results showed that the local Nusselt number is increased with increasing Womersly number (A.) while the dimensionless temperature is increased with Womersly and decreases with amplitude (Ao). The Prandtl number has a significant effect on the local Nusselt number. The results were found in very good agreement with those obtained numerically using the finite volume method. The comparison with the experimental results of other authors gave a reasonable identification.
This research concerns with the fracture behavior of reinforced concrete beams without shear reinforcement numerically. The software ABAQUS is adapted to simulate the crack propagation using the eXtended Finite Element Method (XFEM), taking into account materials nonlinearities using concrete damage plasticity CDP criteria. XFEM is used to solve the discontinuity problems in the simulation. The maximum principal stress failure criterion is selected for damage initiation, and an energy-based damage evolution law based on a model- independent fracture criterion is selected for damage propagation. The traditional nonlinear finite element analysis is used to specify the crack initiation position, which is required to specify the crack location in the analysis of beams using XFEM. Three-dimensional reinforced concrete beam models are investigated subjected to three and four-point loading tests. Simply supported beams under the effect of applied static load are investigated. An elastic perfectly plastic model is used for modeling the longitudinal steel bars. The main variables considered in the study are beam depth and the shear span with beam length. The numerical results are compared with the available experimental results to demonstrate the applicability of the model. The XFEM provides the capability to predict the concrete member fracture behavior.
This study investigates the effect of rotating two rows of horizontal cylinders on forced convection heat transfer in cross flow. Each row consists a three rotating horizontal cylinders heated at constant temperature. The governing equations for the steady, laminar, two dimensional, incompressible flow and constant fluid properties are solved numerically using the finite element method with FlexPDE soft package for a two rows of rotating cylinders at the same direction and at opposite directions. The main parameters are: Reynolds number ( 40 10 Re − = ), Prandtl number ( 7.0 Pr = ), dimensionless longitudinal pitch (SL=1.5-2.5), dimensionless transverse pitch (ST=1.5-2.5) and the dimensionless angular velocity (Ω=0-3) (for both directions clockwise CW and counter clockwise CCW). It is found that the average Nusselt number increased with increasing Re and ST, and decreases with Ω and SL. The results are compared with other authors and give a agreement.
Modern life makes energy, and the source of it is very important. This renewable energy comes from the Earth-Air Heat Exchanger (EAHE) in the soil employed as an air conditioning device for buildings in the climate conditions in Basrah city, south of Iraq. In the present study, the EAHE buried in the soil is simulated numerically using the finite volume method with a soft package. ANSYS: Fluent 2021/R2. A parametric analysis was carried out to determine the effect of three depths ( Z = 1, 2, and 3 m), taking into account the physical properties of the soil in the area under study, which is in the city of Basrah in southern Iraq, at longitude 47.749° and latitude 30.568°, as well as the data and time of 1/6/2023 at 12 p.m., the diameter of the pipe ( D = 7.62, 10.16, and 15.24 cm), and different velocities ( v = 0.5, 1, and 1.5 m/s). The results are presented as a temperature contour and a velocity contour for the performance of EAHE. The important results showed that when the depth of the buried pipe decreases, the temperature of the air outlet and heat exchanger increases; when the diameter decreases, the air outlet temperature from the EAHE and the soil temperature decrease; when the length of the pipe is about 30 m, after this length, the decrease in temperature is very small; and the maximum temperature difference of about 10 °C between the ambient temperature and the outlet temperature of the EAHE was obtained at a depth of 3 m and a velocity of 1 m/s at a diameter of 7.62 cm.
This study is an attempt to determine the salinity intrusion from Arabian Gulf to Shatt Al-Arab River. One dimensional time dependent hydrodynamics model coupled with salinity model were applied and solved numerically by using the explicit finite difference method, a computer program was used to simulate the flow and the salinity concentration. “Total tide” software has been used to get an information about tide level in the day of field measurement, field measurement of salinity and tide velocity in Al-Fao Station was taken for a full tidal cycle and compared with the program results shows a good agreement between field measurement and numerical model results. Three sections were taken along the Shatt Al-Arab River to study the effect of salinity intrusion from the sea. It were found that the effect of salinity intrusion from the sea, reach a distance of a few kilometers upstream of Shatt Al-Arab mouth, but not farther than Abadan region. It is found that the salinity increased rapidly in the last of tidal period to a distance approximately equal 50 km downstream of Karun river or 10 km upstream of Al-Fao, and reach gradually to the salinity of the sea.
In this research work, the influence of cutting parameters and drill point angle on the temperature distribution in dry drilling of stainless steel AISI 304 was numerically investigated by using FE method based on DEFORM-3D V.11 commercial software. Two cutting tools of 10 mm diameter but different in point angles, one is 110° and the other is 118°. These tools were imported from specific website in a format of STL and inserted in the program during modeling of cutting tools. The material of the cutting tools is selected as high-speed steel. The workpiece model is created as cylindrical shape with 50 mm diameter and 5 mm thickness. The cutting parameters are selected as three cutting speeds (100, 200, and 300) rpm, with three feed rates (0.15, 0.25, and 0.35) mm/rev. The depth of hole is fixed for all simulations (3 mm). The percentage of increase or decrease in the resulted temperature according to the various cutting parameter was also calculated and discussed. The best cutting performance of tools according to the change of point angles was also investigated. The results provided a significant influence of cutting speed and tool point angle on the temperature generated in the machined models and very small influence of feed speed on the workpiece temperature.
By using linear wave equation a new model of bubble dynamics in acoustic field is constructed including effects of thermal conduction both inside and outside a bubble, and non-equilibrium evaporation and condensation of water vapour at bubble wall. The liquid temperature at bubble wall is numerically calculated by solving the heat conduction equation (without assuming a profile of liquid temperature). It is including effect of the latent heat of non-equilibrium evaporation and condensation at bubble wall. It is concluded that the liquid temperature increases to the same order of magnitude with that of the maximum temperature attained in the bubble at strong collapses. It is caused by the latent heat of intense vapour condensation and by the thermal conduction from the heated interior of the bubble to the surrounding liquid. The intense vapour condensation takes place at strong collapses because the pressure inside the bubble increases. The comparison is given between the calculated result and the experimental data of radius-time curve for one acoustic cycle. The calculated result fits well with the experimental data.
In this study a two dimensional, steady state propagation of the laminar premixed flame was numerically and experimental are investigated. The energy, momentum, continuity equations for species and global reaction mechanism with equation of stat for ideal gases were solved. Constant temperature boundary condition is applied on axi – symmetric in y – direction domain. The governing equations were discretized by using computation fluid dynamics (CFD) and finite-volume method - central differencing scheme, then solved using Gauss-Seidel Iteration method on uniformed grid with VISUAL BASIC code. Effects of equivalence ratio and initial temperature of fresh gases (air – fuel mixture) were investigated for three types of fuel Methane, Propane and Butane. Also the flame speed and flame temperature were experimentally measured for air – fuel (Methane, Propane, Butane and LPG) mixtures. The burning velocity was calculated depending on the flame speed and flame temperature measuring. The flame speed and flame temperature were measured by using optical technique. Effects of equivalence ratio and initial temperature of fresh gases (air – fuel mixtures) on flame speed and flame temperature are investigated experimentally. Results were generated for the detailed description of the local fluid flow and heat transfer characteristics including temperature, axial velocity, density and mole fractions profiles. For example the flame speed reached 274.4 cm/s as a maximum value at Ø=1.1 for propane air mixture, and flame temperature comparison give a good agreement between theoretical and experimental results at rich mixtyre
This work uses different shapes of intake manifold for study the effect on a single cylinder four stroke gasoline engine. A numerical simulation of the flow achieved through five intake manifold designs, using 3D Computational Fluid Dynamic (CFD) software package FLUINT (6.3.). Accordingly, the three-dimensional resolution of Navier-Stokes equations in conjunction with the standard k-ε turbulence model is undertaken to provide knowledge of the air movement nature and examining the intake manifold optimal geometry. Five cases of intake manifold are examined experimentally in order to produce a comprehensive and realistic data set. These data are in the form of engine performance, exhaust gas products and relative AFR for each case separately under different engine speeds. Exhaust gas analyzer type (Infragas-209) is used in the present work to measure exhaust gas concentrations and relative air/fuel ratio ( ). The results were obtained in this investigation showed that a Simulate numerically and experimentally is capable to select the optimized intake system geometry with reliability. Velocity is highest near the outer wall at increased the curvature ratio and pressure is highest near the inner wall at increased the curvature ratio. The secondary flow increases when the engine speeds and curvature ratio increase because of increasing the pressure difference between the inner wall and the outer wall. The effect of these parameters explained on the swirl air movement and tumble inside the cylinder are increasing by increase the engine speed and γ respectively. The increasing in the engine speed and the optimum selection of the manifold which designed enhanced the mixing of the fuel with air. The results showed that the optimized manifold 135º- NE (case 5) due to enhance AFR, fuel consumption and exhaust emissions are improved.
In this paper, a new model of beam was built to study and simulate the buckling behavior of function graded beam. All equations of motion are derived using the principal of the minimum total potential energy and based on Euler-Bernoulli, first and high order shear deformation Timoshenko beam theory. The Navier solution is used for simply supported beam, and exact formulas found for buckling load. The properties of material of FG beam are assumed to change in thickness direction by using the power law formula. The dimensionless critical buckling load is calculated analytically by the FORTRAN program and numerically by ANSYS software. In the beginning, the analytical and numerical results are validated with results available in previous works and it is also has very good agreement in comparison with and some researchers. In the present study, the lower layer of the graded beam is made up of aluminum metal. As for the properties of the rest of the layers, they are calculated based on the modulus ratios studied. The effect of length to thickness ratio, modulus ratio, and power law index on the dimensionless critical buckling load of function graded beam calculating by FORTRAN and ANSYS programs are discussed. The numerical analysis of function graded beam offers accurate results and very close to the analytical solution using Timoshenko Beam theory.
The thermoelectric behavior of different materials under various conditions has been investigated numerically by using the heat transfer module of the COMSOL Multiphysics software platform. A simulation study of the thermoelectric materials (TEM) performance was created by altering the current applied from 0.1 to 1.0 A and setting the hot side temperature (T H ) as 273 K. The impact of different performance metrics, such as cold side temperature and output voltage, has been proven and investigated. It has been shown that the material of the thermoelectric legs', length of leg, and thickness of electrodes significantly impact the thermal and electrical performance of the thermoelectric (TE) module. Appropriate ranges have been studied in the simulation, such as the amperage values applied to the unit as mentioned above, the length of the leg within a range of 1 to 8 mm, and the thickness of the electrode with different values of 0.1 to 0.5 mm, which will achieve excellent performance for the Thermoelectric unit. Modeling and simulation results demonstrated and revealed the optimal and potential use of bismuth telluride (Bi 2 Te 3 ) as well as lead telluride (PbTe) as suitable for Peltier cooling applications. As for the use of cobalt triantimonide (CoSb 3 ), it is in contrast to the two previous metals, as it is effective and appropriate if applied to power generation. The results are validated with another study from the literature, and there is an excellent agreement with an error rate that does not exceed 0.164%.
The natural convection heat transfer from horizontal isothermal three cylindrical rods inside equilateral triangular enclosure has been studied numerically. The enclosure is filled with air, and the heated rods are located at equal distances (E) from triangle center. A finite element software package (FLEXPDE) is used in the present study to solve the set of non-linear equations governing the process. Solutions are obtained for aspect ratio D/H=1/6 and range of distance E=0.2-0.6 and Rayleigh (Ra) number changes from 103 to 106. The effect of Ra and E were examined. Results are presented by streamlines, isotherms and Nusselt number and it indicates that the Nusselt number is significantly increase with increasing both Ra and E. A comparison of the Nusselt number was made with that obtained by [7], and showed substantial improvement to about 65% in some cases.
The purpose of this paper is to determine a stress intensity factor experimental and numerically in the linear region by using a CT specimen of ductile material with a thickness of 15 mm, a width of 30 mm, and pre-crack 1.3 mm this dimension according to ASTM-E399-12 [1], by pulling the specimen in a 600 kN universal testing machine at a very slow speed rate of 0.5 mm/min. The load is applied until the fracture is accrued, the computer-controlled universal testing machine gives the value of the load and the displacement transducer gives a crack mouth opening displacement. The result showed experimental K I is equal to 75.412 MPa √ m, and numerical K I is equal to74.576 MPa √ m, this test showed a very slight decrease in FEA stress intensity factor compared to that in an experimental result which means the stress intensity factor, K I remains very close between experimental and numerical with an error percentage of about (1.12 %). The finite element analysis provides the best approximation to true fracture toughness values, and it can be used to acquire close parameters if experimental testing is not possible.
Natural convection heat transfer in porous cavity with arc shape wall filled with nanofluid is studied numerically. The right arc shape wall of the cavity is heated at constant temperature (Th) while the left wall is kept cold at constant temperature (Tc), and the other horizontal walls are thermally insulated. The governing equations of the heat transfer and nanofluid flow are solved Flex PDE software. A temperature independent nanofluids properties models are adopted. The investigated parameters are the nanoparticles volume fraction Ø= (0-0.2), Rayleigh number Ra (10-1000) and arc center Ce (1-∞). The results are presented by contour of streamlines, isotherms and the average Nusselt number. The results have showed that the average Nusselt number decreases with increasing Ce and increases with increasing Ra and Ø.
During the pouring of concrete deck, the installation of external bracing between the inner and outer girders may be necessary when the bridge has sharp curve in order to control the deflection and rotation of the girders. However, it is important to minimize the number of external bracing members, as they have expensive cost and they also have opposite effects for the fatigue features of the steel tub girders. The analysis of curved box girder bridges is carried out numerically by the use of finite element method through (ANSYS 19.2) software. The curved box girder with the intermediate external diaphragms was modeled and the analysis was carried out for many parameters like external bracing sections, girders with or without concrete deck, girders with end diaphragms or without them. The study concluded that ANSYS program has a good ability in evaluating the external bracing force comparing with code equations.
In this work, the turbulent buoyancy driven fluid flow and heat transfer in a differentially heated tall rectangular enclosure filled with nanofluid is quantified numerically. The two dimensional governing differential equations (continuity, momentum, energy and low Reynolds number LRN k-ω turbulence equations) are discretized using the finite volume method. SIMPLE algorithm is employed to obtain stabilized solution for high Rayleigh numbers. Two types of nanofluids namely, Al2O3-water and Cu-water, were considered. The effect of Rayleigh number (1010 to 1012), diameter of nanoparticles in the range 25-100 nm, nanoparticle volume fraction in range 0-0.08 and the aspect ratio (30, 40 and 50) on fluid flow and heat transfer are investigated. The present results are compared with previously published work and a qualitative agreement with good validation is obtained. Results show that addition of nanoparticles makes the liquid be more viscous which decreases the vertical velocity component and also decreases the temperature gradient near the walls. Also an announced heat transfer enhancement is obtained with nanoparticle volume fraction reaching a maximum point called optimal volume loading, at which the maximum convective heat transfer is obtained, and then it decreased with further increase of volume fraction.
This paper presents a pressure drop analysis in perforated vertical wellbores for different perforation parameters. The effect of the density of the perforations (number of perforation), the phase angle of the perforations, the diameter of the perforation and the flow rate of the crude oil from the perforations on the pressure drop and the productivity index of the perforated vertical wellbores were studied. The analysis of the vertical wellbore was performed numerically using ANSYS FLUENT 15.0 software. Three dimensional, steady-states, turbulent and incompressible fluid flow is assumed during the numerical solution of the governing equations. The results of this study show that, increased perforation density of the perforated vertical wellbore caused an increase in pressure drop, and also, decreased productivity index due to increasing the friction losses. Friction pressure drop has a significant effect on crude oil flow into the wellbore. When the main velocity is 1.5 m/s and the inlet velocity from the perforations is 2 m/s, the friction pressure drop is about 66 % and the acceleration pressure is approximately 34 % of the total pressure drop.
Parallel flow microchannel heat exchanger performance was numerically investigated, for laminar, 3-D, incompressible and steady state flow with slip flow and temperature jump conditions. The continuity, Navier-Stokes equations and the energy equations for the hot and cold fluids were solved by using finite volumes method and SIMPLE algorithm method with FORTRAN code to obtain the velocity and temperature distributions for the two fluids and the separated wall between them. The main investigation parameter that affected on the performance and effectiveness of heat exchanger are: Reynolds number Re, thermal conductivity ratio Kr, Knudsen number Kn, thickness of separating wall, heat capacity ratio Cr and aspect ratio α. Increasing of Reynolds number, Knudsen number, thickness of separating wall, heat capacity ratio and aspect ratio each separately leads to decrease the effectiveness while increasing of thermal conductivity ratio up to 10 leads to increase the effectiveness. Also, it is found that friction number and Nusselt number both decreases with increasing Knudsen number.