Mixed convection in a partially heated triangular cavity filled with nanofluid having a partially flexible wall and internal heat generation
TL;DR: In this paper, the effects of Richardson number (between 0.05 and 50), internal Rayleigh number (within 10 4 and 10 8 ), size and elastic modulus of the partial flexible wall and nanoparticle volume fraction on the fluid flow and heat transfer were numerically investigated.
Abstract: Numerical study of mixed convection in a partially heated nanofluid-filled lid driven cavity with internal heat generation and having a partial flexible wall was performed. The bottom wall of the triangular enclosure is moving with constant speed and left vertical wall is partially heated. The inclined wall of the cavity is cooled and partially flexible. The governing equations are solved with Galerkin weighted residual finite element method. The effects of Richardson number (between 0.05 and 50), internal Rayleigh number (between 10 4 and 10 8 ), size and elastic modulus of the partial flexible wall and nanoparticle volume fraction (between 0 and 0.04) on the fluid flow and heat transfer were numerically investigated. It was observed that the local and averaged heat transfer reduce as the value of the Richardson number and internal Rayleigh number increase. As the value of the elastic modulus of the inclined wall and nanoparticle volume fraction increase, local and average heat transfer enhance. The discrepancy between the averaged Nusselt number increase for different sizes for the lower values of elastic modulus of the flexible wall. When heat transfer process is effective adding nanoparticles to the base fluid is advantageous.
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TL;DR: In this paper, the effect of radiation on the convection heat transfer rate and the nanofluid entropy generation within a diagonal rectangular chamber is investigated numerically in the presence of a magnetic field.
Abstract: In this paper, the effect of the presence of radiation on the convection heat transfer rate and the nanofluid entropy generation within a diagonal rectangular chamber is investigated numerically in the presence of a magnetic field. The governing equations have been solved via finite volume method using the simple algorithm. In this paper, the effects of Rayleigh number, Hartmann number, magnetic field angle changes, chamber angle changes, entropy parameter, radiation parameter and volume percent of nanoparticles on the entropy generation and heat transfer have been investigated. The results show that with increasing Rayleigh number and decreasing the Hartmann number, the Nusselt number and entropy generation increase and the Bejan number decreases. By increasing the angle of the magnetic field, the heat transfer rate and the entropy generation are reduced and the Bejan number increases. By increasing the angle of the chamber at high Rayleigh numbers, the heat transfer rate increases, or by adding 6% of the nanoparticles to the base fluid, the heat transfer rate increases by 9.3% and the entropy generation increases by 15.5% in the absence of radiation. This increase in the Rd = 3 radiation parameter is 5.4% and 6.2%, respectively. It was also observed that the Nusselt number and the entropy generation increased, and with increasing the radiation parameter, the Bejan number decreased. Increasing the heat transfer rate is more significant at higher Rayleigh numbers by increasing the radiation parameter.
138 citations
TL;DR: In this paper, the effects of the number of fins and their length on heat transfer enhancement and entropy generation are scrutinized using a two-phase approach, and results indicate that adding porous fins with a high Darcy number improves heat transfer while fins with low Darcy numbers can weaken the convection and decline Nusselt number.
135 citations
TL;DR: In this paper, the authors reviewed all the published studies about mixed convection of nanofluids in enclosures and categorized them into four main classes, namely square (and rectangular), triangular, trapezoidal, and unconventional shapes.
110 citations
TL;DR: In this paper, three dimensional numerical simulations have been performed on a cubical cavity using finite volume method and the results of mixed convection and entropy generation are illustrated with particle trajectories, isotherms, Nusselt number and Bejan number.
104 citations
TL;DR: In this paper, the authors investigated radiative magnetohydrodynamic mixed convection boundary layer flow of nanofluids over a nonlinear inclined stretching/shrinking sheet in the presence of heat source/sink and viscous dissipation.
82 citations
Cites background from "Mixed convection in a partially hea..."
...Selimefendigil and Oztop [44] reported that the local and averaged heat transfer enhances as the value of the solid volume fraction of the nanoparticle increases and this more effective for higher values of Richardson number....
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...Very recently Selimefendigil and Oztop [41] reported that as the value of the elastic modulus of the inclined wall and nanoparticle volume fraction increase, local and average heat transfer enhances....
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...Very recently, Selimefendigil and Oztop ([21]) utilized Maxwell’s electrical conductivity model which is used to calculate the effective electrical conductivity of a random suspension of spherical nanoparticles....
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...Recently Selimefendigil and Oztop [4] reported that 14.11 % of averaged heat transfer enhancement is obtained when both cavities are filled with nanofluids at the highest value of nanoparticle volume fractions....
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...Selimefendigil and Oztop [19- 21] adopted FEM to investigate the influence of inclined magnetic field under different geometries which includes backward facing step, cavity with oscillating lid and isothermal cylinders portioned with a conductive ring respectively....
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References
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TL;DR: In this paper, an expression for the viscosity of solutions and suspensions of finite concentration is derived by considering the effect of the addition of one solute-molecule to an existing solution, which is considered as a continuous medium.
Abstract: An expression for the viscosity of solutions and suspensions of finite concentration is derived by considering the effect of the addition of one solute‐molecule to an existing solution, which is considered as a continuous medium.
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TL;DR: In this paper, an experimental correlation for the thermal conductivity of Al2O3 nanofluids as a function of nanoparticle size over a wide range of temperature (from 21 to 71°C).
Abstract: In this letter, we report an experimental correlation [Eqs. (1a) and (1b) or (1c)] for the thermal conductivity of Al2O3 nanofluids as a function of nanoparticle size (ranging from 11nmto150nm nominal diameters) over a wide range of temperature (from 21to71°C). Following the previously proposed conjecture from the theoretical point-of-view (Jang and Choi, 2004), it is experimentally validated that the Brownian motion of nanoparticles constitutes a key mechanism of the thermal conductivity enhancement with increasing temperature and decreasing nanoparticle sizes.
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TL;DR: In this article, a high-resolution, finite difference numerical study is reported on three-dimensional steady-state natural convection of air, for the Rayleigh number range 103⩽ Ra ⩽ 106, in a cubical enclosure, which is heated differentially at two vertical side walls.
534 citations