scholarly journals Progress on numerical simulation of nanofluids: impact of an isothermal spherical partition on the mixed convection of nanofluids within cubic enclosures

2020 ◽  
Vol 307 ◽  
pp. 01016
Author(s):  
A. BOUTRA ◽  
K. RAGUI ◽  
N. LABSI ◽  
Y.K. BENKAHLA ◽  
R BENNACER
Keyword(s):  
Lattice Boltzmann ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Numerical Code ◽  
Three Dimensional Flow ◽  
Boltzmann Method ◽  
Do So

The main objective of our work is to light out the three-dimensional flow of an Ag-water nanofluid within a lid-driven cubical space which equipped with a spherical heater into its center. Due to its crucial role in the characterization of the main transfer within such configurations, impact of some parameters is widely inspected. It consists the Richardson value (0,05 to 50), the solid volume fraction (0% to 10%), as well as the heater geometry (10% ≤ d ≤ 25%). To do so, a numerical code based on the Lattice-Boltzmann method, coupled with a finite difference one, is used. The latter has been validated after comparison between the present results and those of the literature. It is to note that the three dimensions D3Q19 model is adopted based on a cubic Lattice, where each pattern of the latter is characterized by nineteen discrete speeds.

Numerical investigation of nanofluids heat transfer in a channel consisting of rectangular cavities by lattice Boltzmann method

2018 ◽  
Vol 29 (11) ◽  
pp. 1850108 ◽  
Author(s):  
Pouria Ranjbar ◽  
Rasul Mohebbi ◽  
Hanif Heidari
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Numerical Code ◽  
Nusselt Numbers ◽  
Maximum Value ◽  
Laminar Forced Convection ◽  
Boltzmann Method ◽  
Plate Channel

In this study, lattice Boltzmann method (LBM) simulation is performed to investigate laminar forced convection of nanofluids in a horizontal parallel-plate channel with three rectangular cavities. Two cavities are considered as located on the top wall of the channel and one on the bottom wall. The effects of the Reynolds number (100–400), the cavity aspect ratio (AR = 0.25, 0.5), the various distances of the cavities from each other ([Formula: see text]) at different solid volume fractions of nanofluids ([Formula: see text]) on the velocity and the temperature profiles of the nanofluids are studied. In addition, the flow patterns, i.e. the deflection and re-circulation zone inside the cavities, and the local and averaged Nusselt numbers on the channel walls are calculated. The results obtained are used to ascertain the validity of the written numerical code, which points to the excellent agreement across the results. The results show that, as the solid volume fraction of nanofluids is enhanced, the transfer of heat to working fluids increases significantly. Further, the results show that the maximum value of the averaged Nusselt number in the channel is obtained at [Formula: see text] for AR = 0.5 and [Formula: see text] for AR = 0.25. The interval [0.1224, 0.1304] is the best position for the second cavity. It is concluded that the results of this paper are very useful for designing optimized heat exchangers.

scholarly journals Three dimensional fluid flow within a rectangular channel with several cylindrical (and/or) elliptical blocks: lattice boltzmann investigation

2020 ◽  
Vol 307 ◽  
pp. 01015
Author(s):  
A. BOUTRA ◽  
K. RAGUI ◽  
N. LABSI ◽  
Y.K. BENKAHLA ◽  
R BENNACER
Keyword(s):  
Reynolds Number ◽  
Lattice Boltzmann ◽  
Rectangular Channel ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Numerical Code ◽  
Cubic Lattice ◽  
Incompressible Newtonian Fluid ◽  
To Come ◽  
Do So

Through this paper, we investigate numerically a Three-dimensional laminar flow of an incompressible Newtonian fluid within a rectangular channel; including several adiabatic partitions of a cylindrical (and/or) elliptical shape. To do so, a numerical code based on the Lattice Boltzmann approach is used. In other words, three dimensions D3Q19 model is adopted all based on a cubic Lattice, where each pattern of the latter is characterized by nineteen discrete speeds. Our numerical code has been successfully validated after a wide comparison between the present results and those of the literature. By taking into account the Reynolds number, the partitions’ shape impact on the flow fields within the channel is taking all attention and that throughout the time’ Streamlines and the velocity profiles. The pressure drop within our channel is also investigated to come out with the best arrangement of these kinds of partitions within.

Numerical study of natural convection of nanofluid in a semi-circular cavity with lattice Boltzmann method

2019 ◽  
Vol 30 (5) ◽  
pp. 2625-2637 ◽  
Author(s):  
Hanieh Nazarafkan ◽  
Babak Mehmandoust ◽  
Davood Toghraie ◽  
Arash Karimipour
Keyword(s):  
Natural Convection ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Volume Fraction ◽  
Numerical Study ◽  
Solid Volume Fraction ◽  
Circular Cavity ◽  
Cu Nanoparticles ◽  
Content Type ◽  
Boltzmann Method

Purpose This study aims to apply the lattice Boltzmann method to investigate the natural convection flows utilizing nanofluids in a semicircular cavity. The fluid in the cavity is a water-based nanofluid containing Al2O3 or Cu nanoparticles. Design/methodology/approach The study has been carried out for the Rayleigh numbers from 104 to 106 and the solid volume fraction from 0 to 0.05. The effective thermal conductivity and viscosity of nanofluid are calculated by the models of Chon and Brinkman, respectively. The effects of solid volume fraction on hydrodynamic and thermal characteristics are investigated and discussed. The averaged and local Nusselt numbers, streamlines, temperature contours for different values of solid volume fraction and Rayleigh number are illustrated. Findings The results indicate that more solid volume fraction corresponds to more averaged Nusselt number for both types of nanofluids. It is also found that the effects of solid volume fraction of Cu are stronger than those of Al2O3. Originality/value Numerical study of natural convection of nanofluid in a semi-circular cavity with lattice Boltzmann method in the presence of water-based nanofluid containing Al2O3 or Cu nanoparticles.

Two-Side-by-Side Cantilevered Cylinders in a Cross Flow

2006 ◽  
Author(s):  
Y. Liu ◽  
Z. X. Cui
Keyword(s):  
Lattice Boltzmann ◽  
Three Dimensional ◽  
Cross Flow ◽  
Flow Conditions ◽  
Three Dimensional Flow ◽  
Wake Flows ◽  
Wake Interference ◽  
Wake Patterns ◽  
Multiple Relaxation Time ◽  
Boltzmann Method

Three dimensional flow over two side-by-side cantilevered cylinders is numerically studied for understanding the complex wake interference behind the cylinder pair. The two cylinders stand on the ground. The lattice Boltzmann method with multiple relaxation time is used for the solution of three dimensional unsteady flow. The simulations are carried out with Reynolds number Re = 200, aspect ratio L/D = 10 and four transverse pitch ratios: T/D = 1.2, 1.5, 2.0 and 3.0, where Re is defined by incoming velocity U, cylinder diameter D and kinetic viscosity v, L is cylinder span length and T is center to center spacing between the cylinder pair. Numerical results show that the wake patterns depend on not only T/D, but also the end flow conditions. Both the wake street and statistics of fluid force vary along the cylinder span considerably, indicating strong three dimensionality of the wake flows and their interaction.

Natural Convection Flow Simulation of Nanofluid in a Square Cavity Using an Incompressible Generalized Lattice Boltzmann Method

2012 ◽  
Vol 329 ◽  
pp. 69-79 ◽  
Author(s):  
Ahmad Reza Rahmati ◽  
Sina Niazi ◽  
Mehrdad Naderi Beni
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Flow Simulation ◽  
Hydrodynamic Characteristics ◽  
Convection Flow ◽  
Square Cavity ◽  
Boltzmann Method

In this Paper, the Heat Transfer Performance in an Enclosure Including Nanofluids Is Studied. the Velocity Field Is Solved by an Incompressible Generalized Lattice Boltzmann Method and Heat Transfer Is Simulated Using Single-Relaxation-Time Lattice Boltzmann Method. the Hydrodynamics and Thermal Fields Are then Coupled Together Using the Boussinesq Approximation. the Fluid in the Square Cavity Is a Cu-Water Nanofluid. the Effects of Grashof Number and Solid Volume Fraction on Thermal and Hydrodynamic Characteristics Are Investigated. the Results Obtained Clearly Show that Heat Transfer Enhancement Is Possible Using Nanofluids in Comparison to Conventional Fluids. Comparisons with Previously Published Works Are Performed and Found to Be in Excellent Agreement with Existing Data.

THREE-DIMENSIONAL LATTICE BOLTZMANN MODEL RESULTS FOR COMPLEX FLUIDS ORDERING

2005 ◽  
Vol 16 (12) ◽  
pp. 1819-1830
Author(s):  
G. AMATI ◽  
F. MASSAIOLI ◽  
G. GONNELLA ◽  
AIGUO XU ◽  
A. LAMURA
Keyword(s):  
Lattice Boltzmann ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Three Dimensions ◽  
Lattice Boltzmann Model ◽  
Domain Growth ◽  
Late Time ◽  
Extended Defects ◽  
Time Dynamics ◽  
Boltzmann Method

The kinetics of domain growth of fluid mixtures quenched from a disordered to a lamellar phase has been studied in three dimensions. We use a numerical approach based on the lattice Boltzmann method (LBM). A novel implementation for LBM which "fuses" the collision and streaming steps is used in order to reduce memory and bandwidth requirements. We find that extended defects between stacks of lamellae with different orientation dominate the late time dynamics.

Effect of hot obstacle position on natural convection heat transfer of MWCNTs-water nanofluid in U-shaped enclosure using lattice Boltzmann method

2019 ◽  
Vol 29 (1) ◽  
pp. 223-250 ◽  
Author(s):  
Yuan Ma ◽  
Rasul Mohebbi ◽  
Mohammad Mehdi Rashidi ◽  
Zhigang Yang
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Content Type ◽  
Boltzmann Method

Purpose This paper aims to numerically investigate the natural convection heat transfer of multi-wall carbon nanotubes (MWCNTs)-water nanofluid in U-shaped enclosure equipped with a hot obstacle by using the lattice Boltzmann method. Design/methodology/approach The combination of the three topics (U-shaped enclosure, different positions of the hot obstacle and MWCNTs-water nanofluid) is innovative in the present study. In total, 15 different positions of the hot obstacle have been arranged, and the effects of pertinent parameters such as Rayleigh numbers, the solid volume fraction of the MWCNTs nanoparticles on the flow field, temperature distribution and the rate of heat transfer inside the enclosure are also investigated. Findings It is found that the average Nusselt number increased by raising the Rayleigh number, and so did the nanoparticle solid volume fraction regardless the position of the hot obstacle. Moreover, enclosures where the hot obstacle is located at the bottom region proved to provide a better rate of heat transfer at high Rayleigh number (106). It is concluded that at a low Ra number (103-105), the higher heat transfer rate and Nu number will be obtained when the hot obstacle is located in the left or right channel. Originality/value In the literature, no trace of studying the natural convection of nanofluids in U-shaped enclosures with heating obstacles was found. Also, MWCNTs were less used as nanoparticles. As the natural convection of nanofluids in thermal engineering applications would expand the existing knowledge, the current researchers conducted a numerical study of the natural convection of Maxwell nanofluid with MWCNTs in U-shaped enclosure equipped with a hot obstacle by using lattice Boltzmann method.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

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