Sajjadi, H., Amiri Delouei, A., Izadi, M., Mohebbi, R. Investigation of MHD natural convection in a porous media by double MRT lattice Boltzmann method utilizing MWCNT–Fe3O4/water hybrid nanofluid (2019) International Journal of Heat and Mass Transfer, 132, pp. 1087-1104.
DOI: 10.1016/j.ijheatmasstransfer.2018.12.060
ABSTRACT In this paper, a new double multi relaxation time (MRT) Lattice Boltzmann method (LBM) has been used to simulate magnetohydrodynamics (MHD) natural convection in a porous media. A new nanofluid named; multi-walled carbon nanotubes–iron oxide/water nanofluid (MWCNT–Fe3O4/water hybrid nanofluid) has been utilized to investigate the effect of nanoparticle on heat transfer. The thermo-physical properties of the nanofluid have been extracted from experimental results. D2Q9 and D2Q5 lattices are used to solve the flow and temperature fields respectively, and the effect of various parameters such as; Darcy number (Da) (10−2–10−1), Rayleigh number (103 ≤ Ra ≤ 105), porosity (0.4 ≤ ε ≤ 0.9), volume fraction of nanoparticles (0≤ Ø ≤ 0.003) and Hartmann number (0 ≤ Ha ≤ 50) have been investigated. Based on the present results, the new double MRT LBM is a proper method to solve the complex flows such as MHD natural convection in porous media. The results show that augmentation of Rayleigh number increases the heat transfer rate for all cases however by increasing the Hartmann number the effect of Rayleigh number decreases. Also, adding the nanoparticles enhances the average Nusselt number as increases 4.9% for Ra = 105, Da = 10−1, Ha = 50, and ε = 0.9 when the volume fraction of nanoparticles rises from 0 to 0.003. Results indicate that by enhancing Darcy number heat transfer rate increases and average Nusselt number improves by porosity. © 2018 Elsevier Ltd
AUTHOR KEYWORDS: Double MRT-LBM; MHD; MWCNT–Fe3O4 nanoparticle; Nanofluid; Porous media PUBLISHER: Elsevier Ltd
Amiri Delouei, A., Sajjadi, H., Mohebbi, R., Izadi, M. Experimental study on inlet turbulent flow under ultrasonic vibration: Pressure drop and heat transfer enhancement (2019) Ultrasonics Sonochemistry, 51, pp. 151-159.
DOI: 10.1016/j.ultsonch.2018.10.032
ABSTRACT This experimental study examines the impact of ultrasonic vibration on pressure drop and heat transfer enhancement of inlet turbulent flows. A stainless steel tube connected to an ultrasonic transducer and immersed in a constant temperature two-phase fluid was considered as the test section. Regarding the designed configuration, the ultrasonic transducer utilized had an acoustic frequency of 28 kHz and two different power levels of 75 W and 100 W. The experiments were conducted for different ultrasonic power levels, inlet temperatures, and flow rates. The accuracy of measurements was successfully validated via the existing empirical correlations. The results indicate that the effect of ultrasonic vibration on pressure drop and heat transfer enhancement diminishes with the growth of both Reynolds number and inlet temperature. Based on previously reported results on inlet flows with a laminar flow regime, the effect of ultrasonic vibration is very trivial in current turbulent inlet flows (up to 7.28% for heat convection enhancement). The results of the present study will be beneficial for future investigations on designing vibrating heat exchangers. © 2018 Elsevier B.V.
AUTHOR KEYWORDS: Experimental study; Heat transfer enhancement; Pressure drop; Turbulent; Ultrasonic vibration INDEX KEYWORDS: Drops; Heat convection; Heat exchangers; Heat transfer coefficients; Inlet flow; Laminar flow; Pressure drop; Reynolds number; Transducers; Tubular steel structures; Turbulent flow; Ultrasonic effects; Ultrasonic transducers; Ultrasonic waves, Accuracy of measurements; Empirical correlations; Experimental study; Heat Transfer enhancement; Laminar flow regimes; Stainless steel tube; Turbulent; Ultrasonic vibration, Thermoacoustics, article; experimental study; flow rate; heat transfer; laminar flow; thermodynamics; turbulent flow; ultrasound; vibration PUBLISHER: Elsevier B.V.
Ma, Y., Mohebbi, R., Rashidi, M.M., Yang, Z., Sheremet, M.A. Numerical study of MHD nanofluid natural convection in a baffled U-shaped enclosure (2019) International Journal of Heat and Mass Transfer, 130, pp. 123-134.
DOI: 10.1016/j.ijheatmasstransfer.2018.10.072
ABSTRACT In this study, nanofluid natural convection in a baffled U-shaped enclosure in the presence of a magnetic field is investigated. Lattice Boltzmann method (LBM) is used to study present problems. KKL (Koo-Kleinstreuer-Li) correlation is applied to calculate the effective thermal conductivity and viscosity of nanofluid. The effect of the Brownian motion on the effective thermal conductivity is considered in this correlation. The combination of the four topics (nanofluid, U-shaped enclosure, baffle, magnetic field) is the main novelty of the present study. Effect of Rayleigh number, Hartmann number, nanoparticle volume fraction and cavity aspect ratio on the flow field and heat transfer characteristics have been investigated. The results demonstrate that the average Nusselt number increases by increments of the Rayleigh number, nanoparticle solid volume fraction and aspect ratio. However, the rate of heat transfer is suppressed by the magnetic field. The effect of magnetic field on heat transfer is more significant at higher Rayleigh number and the effect of Ra on the average Nusselt number is more noteworthy at lower Ha. Besides, the effect of Rayleigh number on heat transfer enhancement becomes more significant at higher aspect ratio. © 2018 Elsevier Ltd
AUTHOR KEYWORDS: Baffle; KKL correlation; LBM; MHD; Nanofluid; Natural convection INDEX KEYWORDS: Aspect ratio; Brownian movement; Computational fluid dynamics; Enclosures; Magnetic fields; Magnetohydrodynamics; Nanoparticles; Natural convection; Nusselt number; Thermal conductivity; Volume fraction, Baffle; Effect of magnetic field; Effective thermal conductivity; Heat transfer characteristics; Heat Transfer enhancement; Lattice boltzmann methods (LBM); Nanofluids; Nanoparticle volume fractions, Nanofluidics PUBLISHER: Elsevier Ltd
Izadi, M., Mohebbi, R., Delouei, A.A., Sajjadi, H. Natural convection of a magnetizable hybrid nanofluid inside a porous enclosure subjected to two variable magnetic fields (2019) International Journal of Mechanical Sciences, 151, pp. 154-169.
DOI: 10.1016/j.ijmecsci.2018.11.019
ABSTRACT This problem deals with natural convective heat transfer of a magnetic nanofluid in a porous medium subjected to two variable magnetic sources. In many industrial processes, heat transfer is affected by magnetic sources. The equations governing the problem were solved, using the finite element method. The study results were compared to literature ones and a very good consistency was found. The effects of different parameters, namely the magnetic number (Mnf= 100–5000), the strength ratio of the two magnetic sources (γr= 0.2–5), Hartmann number (Ha = 0–50), and porosity coefficient (ε = 0.1–09), on natural convective heat transfer inside a porous cavity have been examined. At low Rayleigh numbers, the average Nusselt number was independent of the strength ratio of the two magnetic sources. At high Rayleigh numbers, the Nusselt number decreases first with increasing the strength ratio of the two magnetic sources and then remains constant. Results also showed that at Ra = 1e4, the Nusselt number increases with increasing the magnetic number; whereas, at Ra = 1e6, the magnetic number has an increasing impact on the Nusselt number only at high γr values. © 2018 Elsevier Ltd
AUTHOR KEYWORDS: Magnetizable hybrid nanofluid; Natural convection; Porous material; Two variable magnetic sources INDEX KEYWORDS: Nanofluidics; Natural convection; Nusselt number; Porous materials, Hartmann numbers; Hybrid nanofluid; Industrial processs; Magnetic nanofluid; Magnetic numbers; Magnetic sources; Natural convective heat transfers; Porous enclosure, Magnetism PUBLISHER: Elsevier Ltd
Amiri Delouei, A., Sajjadi, H., Izadi, M., Mohebbi, R. The simultaneous effects of nanoparticles and ultrasonic vibration on inlet turbulent flow: An experimental study (2019) Applied Thermal Engineering, 146, pp. 268-277.
DOI: 10.1016/j.applthermaleng.2018.09.113
ABSTRACT In the current study, the effects of the ultrasonic vibration and nanoparticles on the pressure drop and heat transfer enhancement of inlet turbulent flow are experimentally investigated. Two important factors in the design of heat exchangers, namely, heat transfer improvement and pressure drop, have been considered at different nanoparticle volume fractions, ultrasonic power levels, and flow rates. Existing experiential correlations are utilized to ensure the accuracy of the measurement instruments. It is observed that the effects of ultrasound vibration are more pronounced on the lower Reynolds number as well as the higher nanoparticle volume fraction. The result indicates that the ultrasonic vibrations could reduce the negative effect of pressure drop and improve the positive effect of heat transfer enhancement caused by nanoparticles up to 15.27% and 11.37%, respectively. The effect of ultrasonic power level variation is also bolder in more concentrated nanofluids and lower flow rates. The results of this work will be useful for designing future-oriented vibrating heat exchangers that also have the ability to work with nanofluid. © 2018 Elsevier Ltd
AUTHOR KEYWORDS: Experimental study; Heat transfer enhancement; Nanofluid; Turbulent flow; Ultrasonic vibration INDEX KEYWORDS: Drops; Heat exchangers; Heat transfer coefficients; Nanoparticles; Pressure drop; Reynolds number; Thermoacoustics; Turbulent flow; Ultrasonic effects; Ultrasonic waves; Volume fraction, Experimental study; Heat Transfer enhancement; Measurement instruments; Nanofluids; Nanoparticle volume fractions; Simultaneous effects; Ultrasonic vibration; Ultrasound vibration, Nanofluidics PUBLISHER: Elsevier Ltd
Ma, Y., Mohebbi, R., Rashidi, M.M., Yang, Z. Simulation of nanofluid natural convection in a U-shaped cavity equipped by a heating obstacle: Effect of cavity's aspect ratio (2018) Journal of the Taiwan Institute of Chemical Engineers, 93, pp. 263-276.
DOI: 10.1016/j.jtice.2018.07.026
ABSTRACT Research on nanofluid for heat transfer enhancement of thermal systems has received great attention owing to the lack of energy sources. In this study, fluid flow and natural convection heat transfer of Al2O3–Water or TiO2–water nanofluid inside a U-shaped cavity consist of a hot obstacle has been investigated numerically by lattice Boltzmann method (LBM). In this paper, different parameters are investigated such as Rayleigh number, the solid volume fraction of the nanoparticles, the U-shaped cavity's aspect ratio and heating obstacle's height on the flow field and heat transfer in the enclosure. The results showed that the Rayleigh number (Ra), cavity aspect ratio (AR) and obstacle's height can be affected on isotherms, streamlines and local and average Nusselt number. The average Nusselt number of the obstacle sides increased by increasing the Ra number and solid volume fraction of nanoparticles (ϕ) regardless the AR. In addition, by increasing the AR, the average Nusselt number increased. At low Ra, the effect of nanoparticles on increment of heat transfer for narrow cavities was more than wide ones. © 2018 Taiwan Institute of Chemical Engineers
AUTHOR KEYWORDS: Cold rib; Hot obstacle; LBM; Nanofluid natural convection; U-shaped cavity's aspect ratio INDEX KEYWORDS: Alumina; Aluminum oxide; Aspect ratio; Computational fluid dynamics; Flow of fluids; Nanoparticles; Natural convection; Nusselt number; Titanium dioxide; Volume fraction, Cavity aspect ratio; Cold rib; Heat Transfer enhancement; Hot obstacle; Lattice boltzmann methods (LBM); Nanofluids; Solid volume fraction; U-shaped, Nanofluidics PUBLISHER: Taiwan Institute of Chemical Engineers
Ranjbar, P., Mohebbi, R., Heidari, H. Numerical investigation of nanofluids heat transfer in a channel consisting of rectangular cavities by lattice boltzmann method (2018) International Journal of Modern Physics C, 29 (11), art. no. 1850108, .
DOI: 10.1142/S0129183118501085
ABSTRACT 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 (Xc′) at different solid volume fractions of nanofluids (•=0 '0.05) 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 Xc′=0.1204 for AR = 0.5 and Xc′=0.1024 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. © World Scientific Publishing Company.
AUTHOR KEYWORDS: Cavities; Channel; Heat transfer; LBM; Nanofluids PUBLISHER: World Scientific Publishing Co. Pte Ltd
Abchouyeh, M.A., Mohebbi, R., Fard, O.S. Lattice Boltzmann simulation of nanofluid natural convection heat transfer in a channel with a sinusoidal obstacle (2018) International Journal of Modern Physics C, 29 (9), art. no. 1850079, .
DOI: 10.1142/S0129183118500791
ABSTRACT The aim of this work is to conduct numerical study of fluid flow and natural convection heat transfer by utilizing the nanofluid in a two-dimensional horizontal channel consisting of a sinusoidal obstacle by lattice Boltzmann method (LBM). The fluid in the channel is a water-based nanofluid containing Cuo nanoparticles. Thermal conductivity and nanofluid's viscosity are calculated by Patel and Brinkman models, respectively. A wide range of parameters such as the Reynolds number (Re=100-400) and the solid volume fraction ranging (φ=0-0.05) at different non-dimensional amplitude of the wavy wall of the sinusoidal obstacle (A=0-20) on the streamlines and temperature contours are investigated in the present study. In addition, the local and average Nusselt numbers are illustrated on lower wall of the channel. The sensitivity to the resolution and representation of the sinusoidal obstacle's shape on flow field and heat transfer by LBM simulations are the main interest and innovation of this study. The results showed that increasing the solid volume fraction φ and Reynolds number Re leads to increase the average Nusselt numbers. The maximum average Nusselt number occurs when the Reynolds number and solid volume fraction are maximum and amplitude of the wavy wall is minimum. Also, by decreasing the A, the vortex shedding forms up at higher Reynolds number in the wake region downstream of the obstacle. © 2018 World Scientific Publishing Company.
AUTHOR KEYWORDS: heat transfer; laminar channel flow; lattice Boltzmann method; nanofluid; Sinusoidal obstacle PUBLISHER: World Scientific Publishing Co. Pte Ltd
Izadi, M., Mohebbi, R., Chamkha, A., Pop, I. Effects of cavity and heat source aspect ratios on natural convection of a nanofluid in a C-shaped cavity using Lattice Boltzmann method (2018) International Journal of Numerical Methods for Heat and Fluid Flow, 28 (8), pp. 1930-1955.
DOI: 10.1108/HFF-03-2018-0110
ABSTRACT Purpose: The purpose of this paper is to consider natural convection of a nanofluid inside of a C-shaped cavity using Lattice Boltzmann method (LBM). Design/methodology/approach: Effects of some geometry and flow parameters consisting of the aspect ratio of the cavity, aspect ratio of the heat source; Rayleigh number (Ra = 103 − 106) have been investigated. The validity of the method is checked by comparing the present results with ones from the previously published work. Findings: The results demonstrate that for Ra = 103, the aspect ratio of the heat source has more influence on the average Nusselt number in contrast to the case of Ra = 106. Contrary to the fact that the average Nusselt number increases non-linearly more than twice because of the increase of the aspect ratio of the enclosure at Ra = 103, the average Nusselt number has a linear relation with the aspect ratio for of Ra = 106. Therefore, upon increasing the Rayleigh number, the efficiency of the aspect ratio of the cavity on the thermal convection, gradually diminishes. Originality/value: The authors believe that all the results, both numerical and asymptotic, are original and have not been published elsewhere. © 2018, Emerald Publishing Limited.
AUTHOR KEYWORDS: Aspect ratio of cavity; Aspect ratio of heat source; C-shaped cavity; Lattice Boltzmann method; Nanofluid; Natural convection heat transfer INDEX KEYWORDS: Computational fluid dynamics; Kinetic theory; Nanofluidics; Natural convection; Nusselt number, C-shaped; Design/methodology/approach; Flow parameters; Heat sources; Lattice Boltzmann method; Lattice boltzmann methods (LBM); Nanofluids; Thermal convections, Aspect ratio PUBLISHER: Emerald Group Publishing Ltd.
Ma, Y., Mohebbi, R., Rashidi, M.M., Manca, O., Yang, Z. Numerical investigation of MHD effects on nanofluid heat transfer in a baffled U-shaped enclosure using lattice Boltzmann method (2018) Journal of Thermal Analysis and Calorimetry, pp. 1-17. Article in Press.
DOI: 10.1007/s10973-018-7518-y
ABSTRACT Lattice Boltzmann method (LBM) was carried out to investigate the effects of magnetic field and nanofluid on the natural convection heat transfer in a baffled U-shaped enclosure. The combination of different specifications of the baffle, LBM, nanofluid and magnetic field is the main innovation in the present study. In order to consider the effect of Brownian motion on the thermal conductivity, Koo–Kleinstreuer–Li model is used to define thermal conductivity and viscosity of nanofluid. Effects of Rayleigh number, Hartmann number, nanoparticle volume fraction, height and position of the baffle on the fluid flow and heat transfer characteristics have been examined. It was found that raising the Rayleigh number and nanoparticle solid volume fraction leads to increase the average Nusselt number irrespective of the position of the hot obstacle. However, the heat transfer rate is suppressed by the magnetic field. The heat transfer enhancement by introducing nanofluid decreases as increasing Rayleigh number, but it increases as increasing the Hartmann number. Moreover, the maximum heat transfer rate was observed when the enclosure equipped with a baffle with (s, h) = (0.2, 0.3) or (0.4, 0.3). © 2018 Akadémiai Kiadó, Budapest, Hungary
AUTHOR KEYWORDS: Baffle; Enclosure; LBM; Magnetic field; Nanofluid; Natural convection; U-shaped INDEX KEYWORDS: Brownian movement; Computational fluid dynamics; Enclosures; Flow of fluids; Kinetic theory; Magnetic field effects; Magnetic fields; Nanoparticles; Natural convection; Numerical methods; Thermal conductivity; Volume fraction, Baffle; Fluid flow and heat transfers; Heat Transfer enhancement; Lattice boltzmann methods (LBM); Nanofluids; Nanoparticle volume fractions; Numerical investigations; U-shaped, Nanofluidics PUBLISHER: Springer Netherlands
Izadi, M., Hoghoughi, G., Mohebbi, R., Sheremet, M. Nanoparticle migration and natural convection heat transfer of Cu-water nanofluid inside a porous undulant-wall enclosure using LTNE and two-phase model (2018) Journal of Molecular Liquids, 261, pp. 357-372.
DOI: 10.1016/j.molliq.2018.04.063
ABSTRACT Using Buongiorno's model, the natural convection of Cu-water nanofluid flowing within a wavy wall porous enclosure at the presence of a cylindrical heater was numerically investigated. The problem is considered such that there is no local thermal equilibrium between two phases of porous media. The effects of Rayleigh number (103 ≤ Ra ≤ 106), the Lewis number (1 ≤ Le ≤ 50), Brownian motion parameter (0.1 ≤ Nb ≤ 0.5), the thermophoresis parameter (0.1 ≤ Nt ≤ 0.5), the buoyancy ratio (0.1 ≤ Nr ≤ 0.5), the Darcy number (10−5 ≤ Da ≤ 10−1), porosity (0.1 ≤ ε ≤ 0.9), the ratio of the thermal conductivity of the nanofluid to the solid phase (0.1 ≤ γs ≤ 10), coefficient of heat transfer at the interface (1 ≤ Nhs ≤ 1000) on hydrodynamic and thermal parameter have been studied. Streamlines, distribution of temperature and concentration of nanoparticles are presented and discussed. Increasing in the Rayleigh, the Darcy, the Lewis numbers, the thermal conductivity ratio and the Brownian parameter of the nanoparticle motions homogenizes the nanofluid. Meanwhile, the homogeneity is reduced as thermophoresis is increased. The results show that the thermal equilibrium model for porous media is applicable for the cases with large heat transfer coefficient at the interface between the solid matrix and the nanofluid. Moreover, the average Nusselt number of both porous phases' increases with the Brownian parameter, while the Nusselt number is reduced as the thermophoresis is increased. © 2018 Elsevier B.V.
AUTHOR KEYWORDS: Buongiorno's model; LTNE model; Migration of nanoparticles; Natural convection; Porous media INDEX KEYWORDS: Brownian movement; Enclosures; Nanoparticles; Natural convection; Nusselt number; Porous materials; Thermal conductivity of solids; Thermophoresis, Cylindrical heaters; Distribution of temperature; Local thermal equilibrium; Motion parameters; Porous enclosure; Thermal conductivity ratio; Thermal equilibrium models; Thermal parameters, Nanofluidics PUBLISHER: Elsevier B.V.
Mohebbi, R., Izadi, M., Amiri Delouei, A., Sajjadi, H. Effect of MWCNT–Fe3O4/water hybrid nanofluid on the thermal performance of ribbed channel with apart sections of heating and cooling (2018) Journal of Thermal Analysis and Calorimetry, pp. 1-14. Article in Press.
DOI: 10.1007/s10973-018-7483-5
ABSTRACT A two-dimensional (2D) numerical simulation is performed to simulate the laminar forced convection of a nanofluid in a ribbed channel with apart heating (cooling) sources using lattice Boltzmann method (LBM). The multi-walled carbon nanotubes–iron oxide nanoparticles/water hybrid nanofluid (MWCNT–Fe3O4/water hybrid nanofluid) is used in this simulation. The velocity field, temperature distribution and heat transfer rate are numerically analyzed with the streamlines and isotherm patterns employing of a house code. In addition, the effect of Reynolds number (Re = 25, 50, 75 and 100), nanoparticle solid volume fraction (ϕ = 0, 0.001, 0.003) and ratio of the blocks height (A = 0.2, 0.3, 0.4) are measured. The results are validated against the results reported in the literature, and a good agreement is reported. The obtained results show a maximum value of 16.49% increase in the average heat transfer coefficient for all the considered cases relative to the base fluid. Moreover, the local Nusselt number proves that the use of blocks on the channel walls can increase the amount of heat transfer. Finally, the average Nusselt number shows a linear dependence on the increasing ratio of blocks height for constant solid volume fraction. The results of this study apply to the industrial equipment heating and cooling applications. © 2018 Akadémiai Kiadó, Budapest, Hungary
AUTHOR KEYWORDS: Apart heating (cooling) sections; Forced convection heat transfer; LBM; Nanofluid; Ribbed channel INDEX KEYWORDS: Computational fluid dynamics; Cooling; Forced convection; Heating; Iron oxides; Magnetite; Multiwalled carbon nanotubes (MWCN); Nanoparticles; Numerical methods; Nusselt number; Reynolds number; Velocity; Volume fraction; Yarn, Apart heating (cooling) sections; Average heat transfers; Iron oxide nanoparticle; Laminar forced convections; Lattice boltzmann methods (LBM); Nanofluids; Ribbed channels; Two-dimensional (2-D) numerical simulation, Nanofluidics PUBLISHER: Springer Netherlands
Ma, Y., Mohebbi, R., Rashidi, M.M., Yang, Z. Numerical simulation of flow over a square cylinder with upstream and downstream circular bar using lattice Boltzmann method (2018) International Journal of Modern Physics C, 29 (4), art. no. 1850030, .
DOI: 10.1142/S0129183118500304
ABSTRACT A numerical investigation is carried out to analyze the flow patterns, drag and lift coefficients, and vortex shedding around a square cylinder using a control circular bar upstream and downstream. Lattice Boltzmann method (LBM) was used to investigate flow over a square cylinder controlled by upstream and downstream circular bar, which is the main novelty of this study. Compared with those available results in the literature, the code for flow over a single square cylinder proves valid. The Reynolds number (Re) based on the width of the square cylinder (D) and diameter of circular bar (d) are 100 for square cylinder, 30 and 50 for different circular bars. Numerical simulations are performed in the ranges of 1≤L/D≤5 and 1≤G/D≤5, where L and G are the center-To-center distances between the bar and cylinder. Five distinct flow patterns are observed in the present study. It is found that the maximum percentage reduction in drag coefficient is 59.86% by upstream control bar, and the maximum percentage reduction in r.m.s. lift coefficient is 73.69% by downstream control bar. By varying the distance ratio for the downstream control bar, a critical value of distance ratio is found where there are two domain frequencies. © 2018 World Scientific Publishing Company.
AUTHOR KEYWORDS: circular bar; LBM; reduction of drag forces; square cylinder; vortex shedding control PUBLISHER: World Scientific Publishing Co. Pte Ltd
Ma, Y., Mohebbi, R., Rashidi, M.M., Yang, Z. Study of nanofluid forced convection heat transfer in a bent channel by means of lattice Boltzmann method (2018) Physics of Fluids, 30 (3), art. no.
DOI: 10.1063/1.5022060
ABSTRACT In this paper, the laminar forced convection heat transfer of nanofluid through a bent channel was numerically investigated. The lattice Boltzmann method was used for solving the governing equations in the domain. The effect of different parameters such as Reynolds number (50 ≤ Re ≤ 150), vertical passage ratio (2.0 ≤ M ≤ 4.0), and nanoparticle solid volume fractions (Φ = 0, 0.01, 0.03, 0.05) are analyzed in terms of streamlines, isotherms, and local Nusselt numbers. It was concluded from this study that the local and average Nusselt number increased with increasing nanoparticle volume fraction regardless of Re and M. Moreover, the effect of the nanofluid concentration on the increment of heat transfer was more remarkable at higher values of the Reynolds number. Simulations show that by increasing the Reynolds number or decreasing the vertical passage ratio, the local and average Nusselt number increases. © 2018 Author(s).
INDEX KEYWORDS: Computational fluid dynamics; Fluidity; Forced convection; Heat convection; Kinetic theory; Nanofluidics; Nanoparticles; Nusselt number; Reynolds number; Volume fraction, Bent channels; Governing equations; Laminar forced convections; Lattice Boltzmann method; Local Nusselt number; Nanofluids; Nanoparticle volume fractions; Solid volume fraction, Heat transfer PUBLISHER: American Institute of Physics Inc.
Izadi, M., Mohebbi, R., Karimi, D., Sheremet, M.A. Numerical simulation of natural convection heat transfer inside a ┴ shaped cavity filled by a MWCNT-Fe3O4/water hybrid nanofluids using LBM (2018) Chemical Engineering and Processing - Process Intensification, 125, pp. 56-66.
DOI: 10.1016/j.cep.2018.01.004
ABSTRACT Natural convection of multi-wall carbon nanotubes-Iron Oxide nanoparticles/water hybrid nanofluid (MWCNT-Fe3O4/water hybrid nanofluid) inside a ┴ shaped enclosure has been numerically investigated using Lattice Boltzmann Method. Numerical in-house code has been developed to study the effects of different parameters including the nanoparticles volume fraction, the Rayleigh number, the cavity obstruction ratio, the heat source position, and the heat source aspect ratio on the hydrodynamic and thermal characteristics. In order to validate the developed numerical code, the results have been compared with previous works and have shown a good concordance. The results indicate that Nusselt number degrades respect to the cavity obstruction ratio because of development of the thermal boundary layer thickness. In addition, an increment of the heat source aspect ratio results in better cooling condition due to decreasing in the boundary layer thickness. © 2018 Elsevier B.V.
AUTHOR KEYWORDS: Cavity aspect ratio; Heat source aspect ratio; Lattice Boltzmann method; Nanofluid; Natural convection heat transfer; ┴ Shaped cavity PUBLISHER: Elsevier B.V.
Mohebbi, R., Lakzayi, H., Sidik, N.A.C., Japar, W.M.A.A. Lattice Boltzmann method based study of the heat transfer augmentation associated with Cu/water nanofluid in a channel with surface mounted blocks (2018) International Journal of Heat and Mass Transfer, 117, pp. 425-435.
DOI: 10.1016/j.ijheatmasstransfer.2017.10.043
ABSTRACT The study of the forced convection in a channel has many practical applications. In this paper, the forced convection heat transfer from surface mounted blocks attached to the bottom wall of a horizontal channel with nanofluid is numerically studied by the second-order lattice Boltzmann method (LBM). The effects of Reynolds numbers and geometrical parameters of the blocks in different aspect ratios on the flow field and temperature distribution for various volume fractions of nanofluid (φ = 0, 0.01, 0.03 and 0.05) are analyzed. Also, the influence of these parameters is investigated on the local and average Nusselt numbers. It is concluded that heat transfer in channels can be enhanced by using the block on the walls and adding nanoparticles. There is a maximum value of 39.04% increase in average heat transfer coefficient for all the examined cases compared to the base fluid (i.e., water). © 2017 Elsevier Ltd
AUTHOR KEYWORDS: Block; Channel; Forced convection; LBM; Nanofluid INDEX KEYWORDS: Aspect ratio; Computational fluid dynamics; Forced convection; Geometry; Heat convection; Kinetic theory; Nanofluidics; Reynolds number; Two phase flow, Average heat transfers; Block; Channel; Heat transfer augmentation; Horizontal channels; Lattice Boltzmann method; Lattice boltzmann methods (LBM); Nanofluids, Heat transfer PUBLISHER: Elsevier Ltd
Mohebbi, R., Rashidi, M.M., Izadi, M., Sidik, N.A.C., Xian, H.W. Forced convection of nanofluids in an extended surfaces channel using lattice Boltzmann method (2018) International Journal of Heat and Mass Transfer, 117, pp. 1291-1303.
DOI: 10.1016/j.ijheatmasstransfer.2017.10.063
ABSTRACT Research on nanofluids for heat transfer augmentation has received a great attention from many researchers. Recently, many numerical works have been conducted to examine their applicability in predicting heat transfer with nanofluids. In the present study, a two-dimensional (2D) lattice Boltzmann method (LBM) was applied for numerical simulation of forced convection in a channel with extended surface using three different nanofluids. The predicted were carried out for the laminar nanofluid flow at low Reynolds number (10 ⩽ Re ⩽ 70), nanofluid concentration (0.00 ⩽ φ ⩽ 0.050), different geometric parameter (0.2 ⩽ A = l/H ⩽ 0.8) and relative height of the extended surfaces (0.05 ⩽ B = h/H ⩽ 0.35). The results indicated that the average Nusselt number increases when the nanofluid concentration increased from 0% to 5%. Moreover, the effect of the nanofluid concentration on the increasing of heat transfer is more noticeable at higher values of the Reynolds number. It is concluded that the use of extended surfaces can enhance the rate of heat transfer for certain arrangements. We also found that the nanofluid with CuO nanoparticles performed better enhancement on heat transfer compared Al2O3/water and TiO2/water nanofluids. © 2017 Elsevier Ltd
AUTHOR KEYWORDS: Extended surfaces; Laminar forced convection; LBM; Nanofluid; Nusselt number; Parallel-plate channel INDEX KEYWORDS: Aluminum compounds; Computational fluid dynamics; Copper compounds; Forced convection; Heat transfer; Kinetic theory; Numerical methods; Nusselt number; Reynolds number; Titanium dioxide, Extended surfaces; Heat transfer augmentation; Laminar forced convections; Lattice Boltzmann method; Nanofluids; Parallel-plate channels; Rate of heat transfer; Two-dimensional (2D) lattice, Nanofluidics PUBLISHER: Elsevier Ltd
Matori, A., Mohebbi, R., Hashemi, Z., Ma, Y. Lattice Boltzmann study of multi-walled carbon nanotube (MWCNT)-Fe3O4/water hybrid nanofluids natural convection heat transfer in a Π-shaped cavity equipped by hot obstacle (2018) Journal of Thermal Analysis and Calorimetry, . Article in Press.
DOI: 10.1007/s10973-018-7881-8
ABSTRACT In the present paper, the effect of nanofluid and the hot obstacle in a Π-shaped cavity is investigated. Lattice Boltzmann method is used to simulate the fluid flow and heat transfer. The effects of the parameters such as the nanoparticle solid volume fraction, the Rayleigh number, aspect ratio of cavity and hot obstacle position on the flow pattern and heat transfer parameters are studied. The numerical results are compared with previous results for validation, and a good agreement obtained. It is found that the average Nusselt number is increased by increasing the nanoparticle solid volume fraction, the Rayleigh number and the aspect ratio of cavity. Moreover, the effect of Rayleigh number on the average Nusselt number at high Rayleigh numbers (105–106) is more pronounced than that at low Rayleigh numbers (103–104) due to the different heat transfer mechanisms. The position of the hot obstacle affects the heat transfer significantly. When the hot obstacle is located on the center, the heat transfer is more effective. © 2018, Akadémiai Kiadó, Budapest, Hungary.
AUTHOR KEYWORDS: Hot obstacle; LBM; MWCNT-Fe3O4/water hybrid nanofluids; Natural convection heat transfer; Π-Shaped cavity INDEX KEYWORDS: Aspect ratio; Computational fluid dynamics; Flow patterns; Iron oxides; Magnetite; Multiwalled carbon nanotubes (MWCN); Nanoparticles; Natural convection; Nusselt number; Volume fraction; Yarn, Fluid flow and heat transfers; Heat transfer mechanism; Hot obstacle; Lattice boltzmann; Lattice Boltzmann method; Nanofluids; Solid volume fraction; Transfer parameters, Nanofluidics PUBLISHER: Springer Netherlands
Ma, Y., Mohebbi, R., Rashidi, M.M., Yang, Z. MHD forced convection of MWCNT–Fe3O4/water hybrid nanofluid in a partially heated τ-shaped channel using LBM (2018) Journal of Thermal Analysis and Calorimetry, . Article in Press. https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055260997&doi=10.1007%2fs10973-018-7788-4&partnerID=40&md5=5ae8c39a005971d63789fca4e6375665
DOI: 10.1007/s10973-018-7788-4
ABSTRACT Forced convection heat transfer of multi-wall carbon nanotubes–iron oxide nanoparticles/water hybrid nanofluid (MWCNT–Fe3O4/water hybrid nanofluid) inside a partially heated τ-shaped channel has been numerically investigated. The effect of magnetic field is taken into account. The governing equations are solved by the lattice Boltzmann method in the domain, and the results were compared with other numerical methods by an excellent agreement between them. The effects of parameters such as Hartmann number (0 ≤ Ha ≤ 60), volume fraction of nanoparticles (0 ≤ ϕ ≤ 0.003) and different location of two heaters on the fluid flow and heat transfer are studied. The results indicate that for all cases, the average Nusselt number of each heater increases as the volume fraction of nanoparticles increases. The heat transfer characteristics were significantly affected by the arrangement of the two heaters. The heaters located on the left half of the top wall is convection-dominant mechanism, and the conduction heat transfer is the primary mechanism when the heater is on the right half of the top wall. The average Nusselt number increases as Ha increases for the heater of dominating convection mechanism but decreases for the heater of dominating conduction mechanism. © 2018, Akadémiai Kiadó, Budapest, Hungary.
AUTHOR KEYWORDS: Forced convection heat transfer; LBM; Magnetic field; Nanofluid; τ-shaped channel INDEX KEYWORDS: Computational fluid dynamics; Flow of fluids; Forced convection; Heat conduction; Iron oxides; Magnetic fields; Magnetite; Multiwalled carbon nanotubes (MWCN); Nanoparticles; Numerical methods; Nusselt number; Volume fraction; Yarn, Conduction Mechanism; Effect of magnetic field; Fluid flow and heat transfers; Governing equations; Heat transfer characteristics; Iron oxide nanoparticle; Lattice Boltzmann method; Nanofluids, Nanofluidics PUBLISHER: Springer Netherlands
Ma, Y., Mohebbi, R., Rashidi, M.M., Yang, Z. Effect of hot obstacle position on natural convection heat transfer of MWCNTs-water nanofluid in U-shaped enclosure using lattice Boltzmann method (2018) International Journal of Numerical Methods for Heat and Fluid Flow, . Article in Press.
DOI: 10.1108/HFF-01-2018-0004
ABSTRACT 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. © 2018, Emerald Publishing Limited.
AUTHOR KEYWORDS: Hot obstacle; Lattice Boltzmann method; MWCNTs-water nanofluid; Natural convection; U-shaped enclosure INDEX KEYWORDS: Computational fluid dynamics; Enclosures; Kinetic theory; Multiwalled carbon nanotubes (MWCN); Nanoparticles; Natural convection; Numerical methods; Thermal Engineering; Volume fraction; Yarn, Design/methodology/approach; Engineering applications; Hot obstacle; Lattice Boltzmann method; Nanofluids; Rate of heat transfer; Solid volume fraction; U-shaped, Nanofluidics PUBLISHER: Emerald Group Publishing Ltd.
Mohebbi, R., Izadi, M., Chamkha, A.J. Heat source location and natural convection in a C-shaped enclosure saturated by a nanofluid (2017) Physics of Fluids, 29 (12), art. no. 122009, .
DOI: 10.1063/1.4993866
ABSTRACT In this work, the effect of the presence of a heat source and its location on natural convection in a C-shaped enclosure saturated by a nanofluid is investigated numerically using the lattice Boltzmann method. Fifteen cases consisting of different heat source locations attached to an isolated wall of the enclosure have been considered to achieve the best configuration at different Rayleigh numbers (103-106) and various solid volume fractions of the nanofluid (0-0.05). Results are shown in terms of the streamlines, isothermal lines, velocity profiles, and the local and average Nusselt numbers. The numerical solution is benchmarked against published results from previous studies for validation, and a good agreement is demonstrated. According to the results, at Ra = 103, the maximum Nusselt number is achieved when the heat source is located within the upper horizontal cavity. Moreover, at higher Rayleigh numbers (Ra = 106) and locations of the heat source within the vertical cavity yield the best Nusselt numbers. Compared to the base fluid and at low Rayleigh numbers, the increase in the Nusselt number of the nanofluid is not found to be dependent on the location of the heat source. However, for high Rayleigh numbers, the maximum increase is obtained when the heat source is located in the upper part of the vertical. © 2017 Author(s).
INDEX KEYWORDS: Computational fluid dynamics; Enclosures; Location; Nanofluidics; Natural convection; Nusselt number, Heat sources; Horizontal cavities; Lattice Boltzmann method; Numerical solution; Rayleigh number; Solid volume fraction; Velocity profiles; Vertical cavity, Heat convection PUBLISHER: American Institute of Physics Inc.
Mohebbi, R., Heidari, H. Lattice Boltzmann simulation of fluid flow and heat transfer in a parallel-plate channel with transverse rectangular cavities (2017) International Journal of Modern Physics C, 28 (3), art. no. 1750042, .
DOI: 10.1142/S0129183117500425
ABSTRACT The aim of this paper is investigating the forced convection heat transfer in a channel with transverse rectangular cavities using the lattice Boltzmann method (LBM) which is not available in the literature yet. The effects of the Reynolds number (100-400), cavity aspect ratio (AR=0.25, 0.5, 1.0), distance of cavities from each other (S′=0,2,4,6) in fixed depth of cavity (A′=0.5) on the velocity and temperature profiles are studied. Moreover, the flow patterns such as deflection and re-circulation zone inside the cavities are obtained. The local and averaged Nusselt numbers on the channel walls are achieved. The results show that the channel with cavities achieves heat transfer enhancements relative to the smooth channel. For the constant cavity aspect ratio, the maximum value of averaged Nusselt number in the channel is obtained in the case of S′=2. Heat transfer to the working fluids increases significantly by increasing the aspect ratio. The existed results are used to ascertain the validity of the numerical code and excellent agreement between results was found. © 2017 World Scientific Publishing Company.
AUTHOR KEYWORDS: forced convection; LBM; parallel-plate channel; rectangular cavities; vortex formation PUBLISHER: World Scientific Publishing Co. Pte Ltd
Mohebbi, R., Rashidi, M.M. Numerical simulation of natural convection heat transfer of a nanofluid in an L-shaped enclosure with a heating obstacle (2017) Journal of the Taiwan Institute of Chemical Engineers, 72, pp. 70-84.
DOI: 10.1016/j.jtice.2017.01.006
ABSTRACT The natural convection heat transfer in an L-shaped enclosure being filled with Al2O3/water nanofluid and having an internal heating obstacle is presented in this paper by LBM. The combination of the three topics (L-shaped cavity, hot obstacle and nanofluid) is the main novelty of the present study. The statistics focused specifically on the effects of different key parameters same as Ra number (103–106), aspect ratio of the channel (0.2–0.6), nano-particle volume fraction of (0–0.05), position and height of the hot obstacle and nanoparticle diameter (20–80 nm) on the heat transfer inside the L-shaped enclosure. The average Nusselt numbers were also calculated for the obstacle sides. The obtained results showed that the streamlines and isotherm lines had different patterns at different Ra numbers, aspect ratio and the height of obstacle. The heat transfer phenomena were highly affected by the heating obstacle position. With the nanofluid and the reducing AR, the increasing Ra number, the decreasing nanoparticle diameter and the increasing height of the obstacle, an increase in the heat transfer and the individual Nusselt number appeared. Moreover, the maximum Nusselt number was observed when the heating obstacle was located in the lower position inside the left wall. © 2017 Taiwan Institute of Chemical Engineers
AUTHOR KEYWORDS: Heating obstacle; L-shaped enclosure; LBM; Nanofluid; Natural convection INDEX KEYWORDS: Aspect ratio; Enclosures; Heat convection; Heating; Nanofluidics; Nanoparticles; Natural convection; Nusselt number, Internal heating; L-shaped; L-shaped cavity; Nanofluids; Nanoparticle diameter; Transfer phenomenon, Heat transfer PUBLISHER: Taiwan Institute of Chemical Engineers
Mohebbi, R., Nazari, M., Kayhani, M.H. Comparative study of forced convection of a power-law fluid in a channel with a built-in square cylinder (2016) Journal of Applied Mechanics and Technical Physics, 57 (1), pp. 55-68.
DOI: 10.1134/S0021894416010077
ABSTRACT A detailed comparison between the lattice Boltzmann method and the finite element method is presented for an incompressible steady laminar flow and heat transfer of a power-law fluid past a square cylinder between two parallel plates. Computations are performed for three different blockage ratios (ratios of the square side length to the channel width) and different values of the power-law index n covering both pseudo-plastic fluids (n < 1) and dilatant fluids (n > 1). The methodology is validated against the exact solution. The local and averaged Nusselt numbers are also presented. The results show that the relatively simple lattice Boltzmann method is a good alternative to the finite element method for analyzing non-Newtonian fluids. © 2016, Pleiades Publishing, Ltd.
AUTHOR KEYWORDS: finite element method; forced convection; lattice Boltzmann method; power-law fluid INDEX KEYWORDS: Computational fluid dynamics; Cylinders (shapes); Forced convection; Heat transfer; Kinetic theory; Laminar flow; Non Newtonian flow; Non Newtonian liquids; Plates (structural components), Comparative studies; Dilatant fluids; Flow and heat transfer; Lattice Boltzmann method; Non-Newtonian fluids; Power law fluid; Pseudoplastic fluid; Square cylinders, Finite element method PUBLISHER: Maik Nauka-Interperiodica Publishing
Nazari, M., Mohebbi, R., Kayhani, M.H. Power-law fluid flow and heat transfer in a channel with a built-in porous square cylinder: Lattice Boltzmann simulation (2014) Journal of Non-Newtonian Fluid Mechanics, 204, pp. 38-49.
DOI: 10.1016/j.jnnfm.2013.12.002
ABSTRACT The lattice Boltzmann method (LBM) has been established as an efficient technique for solving a fluid dynamics problem in a complex porous medium. In this paper, the power-law fluid flow and heat transfer are studied numerically in a channel partially filled with an anisotropic porous block for three power-law indices, n=0.8, 1 and 1.2. Combined pore level simulations of flow and heat transfer are performed for a 2D channel that is partially filled with square obstacles in both ordered and random arrangements. A step by step verification procedure is taken to ensure the accuracy and the physical correctness of the numerical simulation. The effects of the different arrangements of obstacles, Reynolds number, power index n, blockage ratio and porosity on the velocity and temperature profiles are studied. The local and averaged Nusselt numbers are also calculated on the channel walls. It is found that pseudo plastic fluids generate the highest heat transfer rate for all configurations of obstacles. For constant porosity and block size, the increase is noticeable when the arrangement of square obstacles is random. Also by decreasing the porosity, the value of averaged Nusselt number is increased. Two correlations for regular and random obstacle arrangements between the Nusselt number, Reynolds number, power index n, blockage ratio and porosity are presented. The values of averaged Nusselt number with the respective confidence interval are also reported in the case of random arrangement of obstacles. © 2013 Elsevier B.V.
AUTHOR KEYWORDS: Forced convection; LBM; Power-law fluids; Regular and random arrangements; Square obstacles INDEX KEYWORDS: Flow and heat transfer; Lattice boltzmann methods (LBM); Lattice Boltzmann simulations; LBM; Power law fluid; Regular and random arrangements; Square obstacles; Temperature profiles, Computational fluid dynamics; Flow of fluids; Forced convection; Nusselt number; Porous materials; Reynolds number, Porosity