NUMERICAL STUDY COMPARING THE INCIDENCE INFLUENCE BETWEEN REALISTIC WAVE AND REGULAR WAVE OVER AN OVERTOPPING DEVICE

This work presents a numerical study to evaluate the difference between the fluid dynamic behavior of an overtopping device subjected to the incidence of a realistic wave when compared to a regular one; being this regular wave representative of the considered realistic sea state. To do so, the FLUENT software was employed, which is a Computational Fluid Dynamics package based on the Finite Volume Method. The regular wave was generated through a User Defined Function (UDF) that imposes its velocities components as boundary conditions of prescribed velocity. On the other hand, for the realistic wave it was used a methodology to impose the realistic components velocities from transient discrete values, named Table Data (TD) in FLUENT software. For both cases the Volume of Fluid (VOF) multiphase model was applied in the treatment of the water-air interaction. The results showed that the amount of water accumulated in the reservoir for the realistic sea state was 2.46 higher than for the regular wave. This is a relevant finding, since several researches about Overtopping device efficiency were promoted considering only the incidence of regular wave.

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The Influence of Combined Turbulators on the Hydraulic-Thermal Performance and Exergy Efficiency of MWCNT-Cu/Water Nanofluid in a Parabolic Solar Collector: A Numerical Approach

Frontiers in Energy Research ◽

10.3389/fenrg.2021.716549 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yacine Khetib ◽

Ammar Melaibari ◽

Radi Alsulami

Keyword(s):

Solar Collector ◽

Volume Fraction ◽

Numerical Approach ◽

Exergy Efficiency ◽

Multiphase Model ◽

Two Phase ◽

Simpler Algorithm ◽

Fluent Software ◽

Parabolic Geometries ◽

Volume Method

The present research benefits from the finite volume method in investigating the influence of combined turbulators on the thermal and hydraulic exergy of a parabolic solar collector with two-phase hybrid MWCNT-Cu/water nanofluid. All parabolic geometries are produced using DesignModeler software. Furthermore, FLUENT software, equipped with a SIMPLER algorithm, is applied for analyzing the performance of thermal and hydraulic, and exergy efficiency. The Eulerian–Eulerian multiphase model and k-ε were opted for simulating the two-phase hybrid MWCNT-Cu/water nanofluid and turbulence model in the collector. The research was analyzed in torsion ratios from 1 to 4, Re numbers from 6,000 to 18,000 (turbulent flow), and the nanofluid volume fraction of 3%. The numerical outcomes confirm that the heat transfer and lowest pressure drop are relevant to the Re number of 18,000, nanofluid volume fraction of 3%, and torsion ratio of 4. Furthermore, in all torsion ratios, rising Re numbers and volume fraction lead to more exergy efficiency. The maximum value of 26.32% in the exergy efficiency was obtained at a volume fraction of 3% and a torsion ratio of 3, as the Re number goes from 60,000 to 18,000.

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Numerical Study of XCP Probe's Fluid Dynamic Characteristics

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.130-134.1645 ◽

2011 ◽

Vol 130-134 ◽

pp. 1645-1649

Author(s):

Ning Liu ◽

Rui Zhang ◽

Wen Yi Chen ◽

Man Man Zhang

Keyword(s):

Numerical Analysis ◽

Drag Coefficient ◽

Dynamic Characteristics ◽

Numerical Study ◽

Fluid Dynamic ◽

Steady Motion ◽

Experimental Results ◽

Analysis Method ◽

Test Parameters ◽

Volume Method

Applied the finite volume method combining two-equations turbulence model,the influence of fluid dynamic characteristics on XCP probe under different factors be studied The fluid dynamic characteristics were researched under different influencing factors, such as falling speed, rotating rate,seawater density,etc. The drag coefficient under the different falling speeds and the limited velocity of submarine steady motion were obtained. Compared with the experimental results, the simulated results agree well with experimental results, the experiments have show the validity and feasibility of the numerical analysis method. These results will provide theory reference for selecting the reasonable rotating rate, analyzing stability and the movement rule of probe in the water, choosing suitable test parameters for XCP probe of different seawaters.

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Numerical Study of Air-Flow Phenomena Through a Baffled Rectangular Micro-Channel

Journal of Modeling and Optimization ◽

10.32732/jmo.2021.13.2.51 ◽

2021 ◽

Vol 13 (2) ◽

pp. 51-57

Author(s):

Sandip Saha

Keyword(s):

Heat Transfer ◽

Numerical Study ◽

Micro Channel ◽

Flow And Heat Transfer ◽

Flow Phenomena ◽

Turbulent Airflow ◽

Fluent Software ◽

Volume Method

The aim of this study is to investigate the heat transfer characteristics of turbulent airflow phenomena in a rectangular micro-channel in presence of two plane shaped (type-1) and diamond shaped (type-2) baffles which will help to develop various heat exchanger models. Finite volume method has been used to solve the governing equations and the FLUENT software has been employed to visualize the simulation results. For both the baffles, the profile of flow structure, normalized velocity profile, normalized friction factor and average Nusselt number have been investigated with the variations of Reynolds number ranges between [10,000-50,000]. In terms of fluid flow and heat transfer phenomena, it has been found that in the presence of diamond shaped baffles (type-2) are more convenient than plane shaped baffles.

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Numerical Study of the Effect of the Relative Depth on the Overtopping Wave Energy Converters According to Constructal Design

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.348.232 ◽

2014 ◽

Vol 348 ◽

pp. 232-244 ◽

Cited By ~ 9

Author(s):

Elizaldo Domingues dos Santos ◽

Bianca Neves Machado ◽

Marcos Moisés Zanella ◽

Mateus das Neves Gomes ◽

Jeferson Avila Souza ◽

...

Keyword(s):

Wave Energy ◽

Numerical Study ◽

Strong Dependence ◽

Geometric Optimization ◽

Relative Depth ◽

Multiphase Model ◽

Constructal Design ◽

Wave Energy Converters ◽

Low Head ◽

Volume Method

The conversion of wave energy in electrical one has been increasingly studied. One example of wave energy converter (WEC) is the overtopping device. Its main operational principle consists of a ramp which guides the incoming waves into a reservoir raised slightly above the sea level. The accumulated water in the reservoir flows through a low head turbine generating electricity. In this sense, it is performed a numerical study concerned with the geometric optimization of an overtopping WEC for various relative depths:d/λ = 0.3, 0.5 and 0.62, by means of Constructal Design. The main purpose is to evaluate the effect of the relative depth on the design of the ramp geometry (ratio between the ramp height and its length:H1/L1) as well as, investigate the shape which leads to the highest amount of water that insides the reservoir. In the present simulations, the conservation equations of mass, momentum and one equation for the transport of volumetric fraction are solved with the finite volume method (FVM). To tackle with water-air mixture, the multiphase model Volume of Fluid (VOF) is used. Results showed that the optimal shape, (H1/L1)o, has a strong dependence of the relative depth, i.e., there is no universal shape that leads to the best performance of an overtopping device for several wave conditions.

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Numerical Study of Natural Convection in a Partially Open Environment With a Heat Generating Source

Applied Mechanics ◽

10.1115/imece2006-15595 ◽

2006 ◽

Author(s):

Viviana Cocco Mariani ◽

Adriano da Silva

Keyword(s):

Natural Convection ◽

Rayleigh Number ◽

Numerical Study ◽

Fluid Dynamic ◽

Vertical Wall ◽

Internal Heat ◽

Internal Heating ◽

Heating Source ◽

Vertical Walls ◽

The Difference

A numerical study of the thermal and fluid dynamic behavior of air in a partially open two-dimensional enclosure is presented The enclosure has an opening on the right-hand vertical wall, which is kept at a low given temperature, while the opposite wall has a high given temperature. The natural convection in the enclosure is influenced simultaneously by the difference in temperature between the vertical walls, represented by the Rayleigh number (Rae) and by the internal heating source in the enclosure, represented by the Rayleigh number (Rai). The internal heat source is located on the lower horizontal wall, occupying three different positions. The numerical simulations were executed for 103 ≤ Rae ≤ 106 while the intensity of the two effects - the difference in temperature of the vertical walls and the internal heating source - was evaluated based on the relation R = Rai/Rae, which assumed the values of 400, 1000 and 2500. The results obtained in this study are compared with the results reported in the literature, showing a good congruence.

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GEOMETRIC EVALUATION OF FOUR STAGGERED CYLINDERS ARRAY SUBJECTED TO FORCED CONVECTIVE FLOWS BY MEANS OF CONSTRUCTAL DESIGN

Revista de Engenharia Térmica ◽

10.5380/reterm.v18i1.67050 ◽

2019 ◽

Vol 18 (1) ◽

pp. 57

Author(s):

A. P. D. Aghenese ◽

F. B. Teixeira ◽

L. A. O. Rocha ◽

L. A. Isoldi ◽

J. F. Prolo Filho ◽

...

Keyword(s):

Degrees Of Freedom ◽

Numerical Study ◽

Design Method ◽

Fluid Dynamic ◽

Working Fluid ◽

Convective Flows ◽

Constructal Design ◽

Staggered Arrangement ◽

Forced Convective Flow ◽

Volume Method

This work presents a numerical study on the geometric evaluation of forced convective flows over four staggered arrangement of four cylinders. The forced convective flow is considered incompressible, two-dimensional, laminar and unsteady. Geometry varies according to Constructal Design method. The objectives are the maximization of Nusselt number (NuD) and minimization of drag coefficient (CD) between the cylinders and the surrounding flow. Simulations were performed considering Reynolds numbers of ReD = 10, 40 and 150 and air as working fluid, i.e., Prandtl number is assumed Pr = 0.71. The problem presents three degrees of freedom: ST/D (ratio between transversal pitch of the intermediate cylinders and the cylinders diameter), SL1/D (ratio between the frontal and intermediate cylinders longitudinal pitch and the cylinders diameter) and SL2/D (ratio between the intermediate and posterior cylinders longitudinal pitch and the cylinders diameter). However, SL1/D and SL2/D measures were kept fixed at 1.5 and ST/D varies in the range 1.5 ≤ ST/D ≤ 5.0. The conservation equations of mass, momentum and energy conservation are solved with the Finite Volume Method (FVM). Optimal results for fluid-dynamic study in all ReD cases occurred for the lowest values of ST/D, i.e., (ST/D)o,f = 1.5. For thermal analysis, NuD behavior was assessed, where optimal results for ReD = 10 and 40 occurred for the highest values of ST/D, whilst, for ReD = 150, the optimal value was achieved for the intermediate ratio of ST/D = 4.0.

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CFD Comparative Study Between Different Forms of Solar Greenhouses and Orientation Effect

International Journal of Heat and Technology ◽

10.18280/ijht.390212 ◽

2021 ◽

Vol 39 (2) ◽

pp. 433-440

Author(s):

Mohammed Aissa ◽

Azzedine Boutelhig

Keyword(s):

Numerical Study ◽

Physical Problem ◽

Tunnel Structure ◽

Safety Properties ◽

Ansys Fluent ◽

Climate Conditions ◽

Flow Equations ◽

Tunnel Design ◽

Fluent Software ◽

The Difference

Only scarce studies that were adopted have considered two properties, the structure safety and energy, where the aero-dynamic and energetic phenomena were taken into account simultaneously in the agricultural greenhouses area. In fact, in this numerical study, the response of the greenhouse has been investigated in outside climate conditions, by considering the orientation relatively to the wind direction velocity and solar trajectory. A resolution of the physical problem combined between the thermal and dynamical fluid flow equations have been based on the Ansys Fluent software. The results showed that the difference between inside and outside air temperature of greenhouse has been strongly affected by the reorientation of the tunnel greenhouse structure, or by the design of the tunnel structure that was adopted in the dome and chapel shape. Moreover, the safety properties of greenhouse structure linked to the drag stress can be developed when based on the interaction fluid-structure analysis. In this view, a temperature profile evolution versus different heights inside greenhouse was highlighted. As well as like continues of our previous study of the drag evolution over tunnel design body proved by the results found in the literature will be compared with chapel and dome designs.

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Numerical Study of Laminar Forced Convection of Nanofluid in a New Microchannel Heat Sink

Strojnícky casopis – Journal of Mechanical Engineering ◽

10.2478/scjme-2021-0015 ◽

2021 ◽

Vol 71 (2) ◽

pp. 31-40

Author(s):

Bouhabel Bourhane ◽

Kabar Yassine

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Heat Sink ◽

Numerical Study ◽

Microchannel Heat Sink ◽

Ansys Fluent ◽

Mixing Chamber ◽

Fluent Software ◽

Volume Method ◽

Laminar Forced Convection

Abstract The heat transfer and pressure drop in a microchannel heat sink with 02 mixing chambers with inclined walls were numerically studied. The transport equations have been resolved by the finite volume method using ANSYS Fluent software. The operating fluids are water and Al2O3-water. The results obtained for Reynolds numbers ranging from 187 and 705 show that adding a micro-mixing chamber with a rectangular rib in the microchannel improves the heat transfer and increases the pressure drop compared to conventional microchannels. The new shape of the mixing chamber studied shows a net decrease in pressure drop, which improves the performance of the micro heat sink by 5.6%.

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Comparing different CFD software with NACA 2412 airfoil

Progress in Agricultural Engineering Sciences ◽

10.1556/446.2020.00004 ◽

2020 ◽

Author(s):

Csaba Hetyei ◽

Ildikó Molnár ◽

Ferenc Szlivka

Keyword(s):

Fluid Dynamics ◽

Numerical Simulation ◽

Fluid Dynamic ◽

Aerospace Industry ◽

Measured Data ◽

Theoretical Knowledge ◽

Dynamic Simulations ◽

Computational Fluid Dynamics Cfd ◽

The Difference ◽

Volume Method

AbstractThe engineering application's design process starts with a concept, based on our theoretical knowledge and continues with a numerical simulation. In our paper, we review the finite volume method (FVM) which is used generally for heat and fluid dynamic simulations.We compare three different computational fluid dynamics (CFD) software (based in the fine volume method) for validating a NACA airfoil, which can be used for example in the aerospace industry for an airplane's wing profile, and it can be used for example in the renewable industry for a wind turbine's blade or a water turbine's impeller profile. At the end of this paper, the result of our simulations will be compared with a validation case and the difference between the CFD software and the measured data will be presented.

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