scholarly journals Thermal Convection of Nanoliquid in a Double-Connected Chamber

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 588 ◽  
Author(s):  
Ioan Pop ◽  
Mikhail A. Sheremet ◽  
Teodor Groşan
Keyword(s):  
Stream Function ◽  
Heat Conductivity ◽  
Single Phase ◽  
Energy Transport ◽  
Block Size ◽  
Computational Time ◽  
Convective Thermal ◽  
Nanoparticles Concentration ◽  
Internal Block ◽  
Thermally Conducting

Thermogravitational convective thermal transmission, inside a square differentially-heated chamber with a nanoliquid, has been examined in the presence of internal adiabatic or a thermally-conducting solid body. A single-phase nanoliquid approach is employed, based on the experimentally-extracted relations for nanofluid heat conductivity and dynamic viscosity. The governing equations have been written using non-primitive parameters such as stream function and vorticity. Such approach allows a decrease in computational time due to a reduction of equation numbers. One of the main challenges in such a technique is a determining the stream function magnitude at the inner body walls. A solution of this problem has been described in detail in this paper. Computational scrutinizing has been performed by employing the finite difference technique. The mesh sensitivity analysis and comparison with theoretical and experimental results of other researchers have been included. An influence of the Rayleigh number, nanoparticles concentration, internal block size, heat conductivity ratio and non-dimensional time on nanofluid motion and energy transport has been studied.

Thermogravitational convection of Al2O3-H2O nanoliquid in a square chamber with intermittent blocks

2019 ◽  
Vol 30 (3) ◽  
pp. 1365-1378 ◽  
Author(s):  
Mikhail A. Sheremet ◽  
Hakan F. Öztop ◽  
Nidal Abu-Hamdeh
Keyword(s):  
Energy Transport ◽  
Passive Element ◽  
Cross Sectional ◽  
Content Type ◽  
Extra Energy ◽  
Convective Thermal ◽  
Nanoparticles Concentration ◽  
Technical Solutions ◽  
Heat And Fluid Flow ◽  
Local Block

Purpose The purpose of this study is to work on heat transfer enhancement within different engineering cavities is the major aim of most technical solutions. Such intensification can be obtained by using “smart” liquids known as nanoliquids and solid fins. Therefore, free convective thermal transmission within square nanoliquid chamber under the influence of complex fins is studied. The considered fins are the combination of wall-mounted adiabatic fin and an adiabatic block over this fin. Design/methodology/approach Influences of the Rayleigh number, location of the local adiabatic block and nanoparticles concentration on liquid motion and energy transport are studied. Finite difference technique was used to solve the governing equations. Findings It has been ascertained that the energy transport intensification can be reached for the middle position of this local block within the cavity. Originality/value The main originality of this work is to use intermittent block in a nanofluid filled cavity under differentially heated conditions. One constant and location of one of the passive element is constant and other one is fixed, which is the intermittent block, is used to control heat and fluid flow. Thus, distance between blocks is allowed to control of the velocity and kinetic energy. In this way, temperature distribution also can be controlled inside the square cross-sectional closed space. Another originality of the work is to use nanoparticle added main flow for this geometry. Thus, energy efficiency can be controlled via adiabatic intermittent blocks without spending any extra energy.

scholarly journals Multiphysics CFD Simulation for Design and Analysis of Thermoelectric Power Generation

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4344
Author(s):  
Olle Högblom ◽  
Ronnie Andersson
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Electric Power ◽  
Energy Transport ◽  
Dynamic Properties ◽  
Temperature Drop ◽  
Computational Time ◽  
Cfd Analysis ◽  
Electric Power Generation ◽  
Thermoelectric Heat

The multiphysics simulation methodology presented in this paper permits extension of computational fluid dynamics (CFD) simulations to account for electric power generation and its effect on the energy transport, the Seebeck voltage, the electrical currents in thermoelectric systems. The energy transport through Fourier, Peltier, Thomson and Joule mechanisms as a function of temperature and electrical current, and the electrical connection between thermoelectric modules, is modeled using subgrid CFD models which make the approach computational efficient and generic. This also provides a solution to the scale separation problem that arise in CFD analysis of thermoelectric heat exchangers and allows the thermoelectric models to be fully coupled with the energy transport in the CFD analysis. Model validation includes measurement of the relevant fluid dynamic properties (pressure and temperature distribution) and electric properties (current and voltage) for a turbulent flow inside a thermoelectric heat exchanger designed for automotive applications. Predictions of pressure and temperature drop in the system are accurate and the error in predicted current and voltage is less than 1.5% at all exhaust gas flow rates and temperatures studied which is considered very good. Simulation results confirm high computational efficiency and stable simulations with low increase in computational time compared to standard CFD heat-transfer simulations. Analysis of the results also reveals that even at the lowest heat transfer rate studied it is required to use a full two way coupling in the energy transport to accurately predict the electric power generation.

scholarly journals POD-Galerkin Model for Incompressible Single-Phase Flow in Porous Media

Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 588-601 ◽  
Author(s):  
Yi Wang ◽  
Bo Yu ◽  
Shuyu Sun
Keyword(s):  
Porous Media ◽  
Large Scale ◽  
Single Phase ◽  
Galerkin Projection ◽  
Flow In Porous Media ◽  
Computational Time ◽  
Speed Up ◽  
Fast Prediction ◽  
Proper Orthogonal ◽  
Phase Fluid

AbstractFast prediction modeling via proper orthogonal decomposition method combined with Galerkin projection is applied to incompressible single-phase fluid flow in porous media. Cases for different configurations of porous media, boundary conditions and problem scales are designed to examine the fidelity and robustness of the model. High precision (relative deviation 1.0 × 10−4% ~ 2.3 × 10−1%) and large acceleration (speed-up 880 ~ 98454 times) of POD model are found in these cases. Moreover, the computational time of POD model is quite insensitive to the complexity of problems. These results indicate POD model is especially suitable for large-scale complex problems in engineering.

scholarly journals High Speed Parallel SAD Architecture Implementation on FPGA for HEVC encoder

2019 ◽  
Vol 8 (6) ◽  
pp. 1235-1238
Keyword(s):  
Motion Estimation ◽  
Video Compression ◽  
High Speed ◽  
High Performance ◽  
High Efficiency ◽  
Block Size ◽  
Video Encoding ◽  
Computational Time ◽  
Absolute Difference ◽  
Asymmetric Mode

Video compression is a very complex and time consuming task which generally pursuit high performance. Motion Estimation (ME) process in any video encoder is responsible to primarily achieve the colossal performance which contributes to significant compression gain. Summation of Absolute Difference (SAD) is widely applied as distortion metric for ME process. With the increase in block size to 64×64 for real time applications along with the introduction of asymmetric mode motion partitioning(AMP) in High Efficiency Video Encoding (HEVC)causes variable block size motion estimation very convoluted. This results in increase in computational time and demands for significant requirement of hardware resources. In this paper parallel SAD hardware circuit for ME process in HEVC is propound where parallelism is used at various levels. The propound circuit has been implemented using Xilinx Virtex-5 FPGA for XC5VLX20T family. Synthesis results shows that the propound circuit provides significant reduction in delay and increase in frequency in comparison with results of other parallel architectures.

Optimized Accelerating Parameters of Convergence for the Navier-Stokes Equations

1992 ◽  
Author(s):  
Bashar S. AbdulNour
Keyword(s):  
Stream Function ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Relaxation Method ◽  
Reynolds Numbers ◽  
Computer Time ◽  
Navier Stokes ◽  
Computational Time ◽  
Navier Stokes Equations ◽  
Successive Over Relaxation

Abstract An over-relaxation procedure, that includes weighing factors, is applied to the steady, two-dimensional Navier-Stokes equations in order to reduce the computational time. The benefits obtained from this strategy are illustrated by the problem of viscous flow in the entrance region of an unconstricted and a constricted channel. The describing equations are expressed in terms of the stream function and vorticity. The convergence domain for the Successive Over-Relaxation method and the optimum values of the accelerating parameters, which consist of the over-relaxation and weighting factors for both the stream function and vorticity, are discussed. Numerical solutions are obtained for Reynolds numbers ranging from 20 to 2000. The computer time is reduced by as much as a factor of six using the optimum values of the accelerating parameters.

AGN Accretion Disks with Finite Turbulent Prandtl Number

1994 ◽  
Vol 159 ◽  
pp. 482-482
Author(s):  
O. M. Heinrich
Keyword(s):  
Prandtl Number ◽  
Accretion Disks ◽  
Heat Conductivity ◽  
Energy Transport ◽  
Turbulent Energy ◽  
Turbulent Heat ◽  
Thermodynamic Quantities ◽  
Specific Heats ◽  
Disk Structure ◽  
Main Component

The present paper reports results of a study of turbulent energy transport in AGN accretion disks. We follow the spirit of the papers by Shakura et al. and Rüdiger et. al in which the concept of an eddy heat conductivity was introduced and developed. For the viscosity we use a standard α− description with the main component of the stress tensor trø proportional to the gas pressure. The dimensionless Prandtl number Pr given as the ratio of turbulent kinematic viscosity and turbulent heat conductivity enters the model as a free parameter. The disk structure depends sensitively on material properties such as opacities and specific heats. In our calculations we have used an equation of state and mean opacities taking into account a list of the most important ionization processes as well as the radiation contributions to thermodynamic quantities.

Smoothed Particle Hydrodynamics Simulation of Oil-Jet Gear Interaction1

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Marc C. Keller ◽  
Samuel Braun ◽  
Lars Wieth ◽  
Geoffroy Chaussonnet ◽  
Thilo F. Dauch ◽  
...  
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Single Phase ◽  
Jet Impingement ◽  
Spur Gear ◽  
Computational Effort ◽  
Computational Time ◽  
Resistance Torque ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Oil Jet

In this paper, the complex two-phase flow during oil-jet impingement on a rotating spur gear is investigated using the meshless smoothed particle hydrodynamics (SPH) method. On the basis of a two-dimensional setup, a comparison of single-phase SPH to multiphase SPH simulations and the application of the volume of fluid method is drawn. The results of the different approaches are compared regarding the predicted flow phenomenology and computational effort. It is shown that the application of single-phase SPH is justified and that this approach is superior in computational time, enabling faster simulations. In the next step, a three-dimensional single-phase SPH setup is exploited to predict the flow phenomena during the impingement of an oil-jet on a spur gear for three different jet inclination angles. The oil’s flow phenomenology is described and the obtained resistance torque is presented. Thereby, a significant effect of the inclination angle on the oil spreading and splashing process as well as the resistance torque is identified.

Tie-Simplex-Based Phase-Behavior Modeling in an IMPEC Reservoir Simulator

SPE Journal ◽  
2013 ◽  
Vol 19 (02) ◽  
pp. 327-339 ◽  
Author(s):  
M.. Rezaveisi ◽  
K.. Sepehrnoori ◽  
R.T.. T. Johns
Keyword(s):  
Stability Analysis ◽  
Phase Behavior ◽  
Single Phase ◽  
Potential Method ◽  
Phase Region ◽  
Behavior Modeling ◽  
Computational Time ◽  
University Of Texas ◽  
Fully Implicit ◽  
Reservoir Simulator

Summary Recently, tie-simplex-based phase-behavior modeling in reservoir simulators has been applied and investigated as a potential method for improving the computational speed of equation-of-state (EOS) -based reservoir simulators. We implemented compositional-space adaptive tabulation (CSAT), the most promising tie-simplex-based method, in UTCOMP, the University of Texas' in-house IMPEC compositional reservoir simulator, to investigate its computational efficiency compared with the phase-behavior algorithm in UTCOMP. The results show that applying CSAT only to skip stability analysis does improve computational time, but only when a significant portion of the gridblocks are in the single-phase region and no other technique for avoiding stability analysis is used. However, in most cases, there is little or no computational advantage to use of CSAT when the simple option in UTCOMP is used where stability analysis is skipped for blocks surrounded by single-phase regions. We explore in detail the performance of CSAT, which depends significantly on the specific gas flood modeled, and the number of tie-lines generated during adaptive tabulation. The results shed light on applicability of CSAT in the IMPEC-type compositional reservoir simulators and show that the advantages of CSAT in this type of simulator are not as great as are reported in the literature for fully implicit or adaptive implicit formulations.

An Analysis of Cryptographic Algorithms in IoT

2019 ◽  
pp. 83-104
Author(s):  
Samed Bajrić
Keyword(s):  
Information Exchange ◽  
Energy Transport ◽  
Block Size ◽  
Physical World ◽  
Heterogeneous Environment ◽  
Privacy And Security ◽  
Security Issues ◽  
Secure Information ◽  
Cryptographic Algorithms ◽  
The Internet Of Things

The underlying vision of the internet of things (IoT) is to create a world where the real and the virtual realms are converging to create smart environments that makes energy, transport, cities, and many other areas more intelligent. With the IoT, the physical world is being interfaced through the things to the virtual world in heterogeneous environment. In heterogeneous environment, privacy and security are the major challenges. The secure information exchange is most critical pitfall to ensure the system security. This chapter gives a detailed analysis of cryptographic algorithms in IoT. A comparison of lightweight cryptography algorithms on basis of block size, key size, gate equivalents, and throughput is given. Moreover, the various security issues in IoT are discussed along with possible solution.

Smoothed Particle Hydrodynamics Simulation of Oil-Jet Gear Interaction

2017 ◽  
Author(s):  
Marc C. Keller ◽  
Samuel Braun ◽  
Lars Wieth ◽  
Geoffroy Chaussonnet ◽  
Thilo F. Dauch ◽  
...  
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
High Speed ◽  
Single Phase ◽  
Jet Impingement ◽  
Spur Gear ◽  
Computational Time ◽  
Qualitative Comparison ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Oil Jet

In this paper the complex two-phase flow during oil-jet impingement on a rotating spur gear is investigated using the meshless Smoothed Particle Hydrodynamics (SPH) method. A comparison of single-phase SPH to multi-phase SPH simulation and the application of the Volume of Fluid method on the basis of a two-dimensional setup is drawn. The results of the different approaches are compared regarding the predicted flow phenomenology and computational effort. It is shown that the application of single-phase SPH is justified and that this approach is superior in computational time, enabling faster simulations. In a next step, a three-dimensional single-phase SPH setup is exploited to predict the flow phenomena during the impingement of an oil-jet on a spur gear for various jet inclination angles. Thereby, a significant effect of the inclination angle on the oil spreading and splashing process is revealed. Finally, a qualitative comparison to an experimental high-speed image shows good accordance.

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