scholarly journals Free Convection in a Triangular Cavity Filled with Hybrid-Nanofluid along with Sinusoidal Heat

2019 ◽  
Vol 4 (12) ◽  
pp. 48-52
Author(s):  
Md.Rakibul Hasan ◽  
Md. Borhan Uddin ◽  
Ahmed M. U.
Keyword(s):  
Nusselt Number ◽  
Rayleigh Number ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Numerical Study ◽  
Hybrid Nanofluid ◽  
Cool Temperature ◽  
Governing Equations ◽  
Uniform Cool ◽  
Generation Parameter

A numerical study on convective heat transfer of hybrid nanofluid packed in a right angled triangular cavity heated by a sinusoidal temperature maintained from lower side and subjected to a constant magnetic field have been studied in this work. The hypotenuse side of the triangular cavity has been kept in uniform cool temperature while the remaining side is insulated. The governing equations of the problem have been discretized numerically with help of finite element method. A fixed Prandtl number Pr=6.2 has been used for the numerical solution. Several values of Rayleigh number Ra=102-106 , and Hartmann number Ha=0-100 which are the non-dimensional governing parameters have been examined. The volume fraction  =0.01, 0.05, 0.1 and the heat generation parameter Q = 1 have been taken for this work. Calculate and the graph of Nusselt number corresponding to different parameters have been presented. The results show that Nusselt number has been decreasing function of nanoparticles Rayleigh number and also it is a decreasing function of Hartmann number. Obtained results has been compared with previously obtained data by other authors.

scholarly journals MHD Free Convective Heat Transfer in a Triangular Enclosure Filled with Copper-Water Nanofluid

2020 ◽  
pp. 29-38 ◽  
Keyword(s):  
Nusselt Number ◽  
Rayleigh Number ◽  
Average Nusselt Number ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Free Convective Flow ◽  
Nanoparticles Volume Fraction ◽  
Triangular Enclosure ◽  
Element Technique ◽  
Horizontal Side

Two-dimensional time-independent free convective flow and temperature flow into a right-angled triangle shape cavity charged by Cu-H2O nanofluid has been performed. The horizontal side of the enclosure is warmed uniformly T=Th whilst the standing wall is cooled at low-temperature T=Tc and hypotenuse of the triangular is insulated. The dimensionless non-linear governing PDEs have been solved numerically employing the robust PDE solver the Galerkin weighted residual finite element technique. An excellent agreement is founded between the previous, and present studies. The outcomes are displayed through streamline contours, isotherm contours, and local and average Nusselt number for buoyancy-driven parameter Rayleigh number, Hartmann number, and nanoparticles volume fraction. The outcomes show that the temperature flow value significantly changes for the increases of Rayleigh number, Hartmann number, and nanoparticles volume fraction. Average Nusselt number is increased for the composition of nanoparticles whereas diminishes with the increase of Hartmann number.

Effects of different thermal modes of obstacles on the natural convective Al2O3-water nanofluidic transport inside a triangular cavity

2022 ◽  
pp. 095440622110614
Author(s):  
Nilankush Acharya
Keyword(s):  
Nusselt Number ◽  
Rayleigh Number ◽  
Heat Transport ◽  
Hartmann Number ◽  
Volume Fraction ◽  
High Heat ◽  
Flow Profile ◽  
Galerkin Finite Element ◽  
Transport Enhancement ◽  
Number Formula

This study investigates the Al2O3-water nanofluidic transport within an isosceles triangular compartment with top vertex downwards. The top wall is maintained isothermally cooled and left as well as right inclined walls are made uniformly heated. Two diamond-shaped obstacles are positioned inside the enclosure. The nanofluidic motion is supposed to be magnetically influenced. This investigation includes a fine analysis of how various thermal modes of obstacles affect the velocity and thermal profiles of the nanofluid. Appropriate similarity conversion leads to having a non-dimensional flow profile and is treated with Galerkin finite element scheme. The grid independency, experimental verification, and comparison assessments are directed to explore the model accuracy. The dynamic parameters like Rayleigh number [Formula: see text], nanoparticle volume fraction [Formula: see text], and Hartmann number [Formula: see text] are varied to perceive the noteworthy changes in isotherms, velocity, streamlines, and Nusselt number. The consequences specify average Nusselt number deteriorates for Hartmann number but escalates for nanoparticle concentration and Rayleigh number. Both heated and adiabatic obstacles exhibit high heat transport, while cold obstacles reveal the lowest magnitude in heat transmission. For Rayleigh number, cold obstacles reveal 34.51% heat transport enhancement, whereas it is 52.72% for heated obstacles compared to cold one. mathematics subject classification: 76W05

Investigation of magnetohydrodynamics in Ag-TiO2/water hybrid nanofluid in a Shamse knot shaped cavity

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yuan Ma ◽  
Mohammad Mehdi Rashidi ◽  
Rasul Mohebbi ◽  
Zhigang Yang
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Side Length ◽  
Hybrid Nanofluid ◽  
Nanoparticle Volume Fraction ◽  
Heat Transfer Characteristics ◽  
Content Type

Purpose The nanofluid natural convection heat transfer in a hollow complex enclosure, which is named as Shamse knot shape, is studied numerically. This paper aims to present how the Rayleigh number, nanoparticle volume fraction, Hartmann number and hollow side length affect the fluid flow and heat transfer characteristics. Design/methodology/approach The continuity, momentum and energy equations have been solved using lattice Boltzmann method (LBM). Numerical simulation has been obtained for a wide range of Rayleigh number (103 ≤ Ra ≤ 106), nanoparticle volume fraction (0 ≤ ϕ 0.05) and Hartmann number (0 ≤ Ha ≤ 60) to analyze the fluid flow pattern and heat transfer characteristics. Moreover, the effect of hollow side length (D) on flow field and thermal performance is studied. Findings The results showed that the magnetic field has a negative effect on the thermal performance and the average Nusselt number decreases by increasing the Hartmann number. Because of the high conduction heat transfer coefficient of nanoparticles, the average Nusselt number increases by rising the nanoparticle volume fraction. The effect of adding nanoparticles on heat transfer is more effective at low nanoparticle volume fraction (0 ≤ ϕ ≤ 0.01). It was also found that at Ra = 106, when the hollow side length increases to 3, the flow pattern becomes different due to the small gap. The averaged Nu is an increasing function of D at low Ra and an opposite trend occurs at high Rayleigh number. Originality/value For the first time, the effects of magnetic field, Rayleigh number, nanoparticle volume fraction and hollow side length on natural convection heat transfer of hybrid nanofluid (Ag-TiO2/water) is investigated in a complicated cavity.

Investigation of heat transfer of MHD Al2O3/water nanofluid in an enclosure with a semicircular wall and a heating obstacle

2019 ◽  
Vol 30 (12) ◽  
pp. 1950105 ◽  
Author(s):  
Yuan Ma ◽  
Zhigang Yang
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Flow Pattern ◽  
Average Nusselt Number ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Nanoparticle Volume Fraction ◽  
Number Formula

Lattice Boltzmann method (LBM) was used to simulate two-dimensional MHD Al2O3/water nanofluid flow and heat transfer in an enclosure with a semicircular wall and a triangular heating obstacle. The effects of nanoparticle volume fraction ([Formula: see text]), Rayleigh number [Formula: see text], Hartmann number [Formula: see text] and heating obstacle position (Cases 1–7) on flow pattern, temperature distribution and rate of heat transfer were investigated. The results show that with the enhancing Rayleigh number, the increasing nanoparticle volume fraction and the reducing Hartmann number, an enhancement in the average Nusselt number and the heat transfer appeared. The effect of Ha on the average Nu increases by increasing the Ra. It can also be found that the action of changing the heating obstacle position on the convection heat transfer is more important than that on the conduction heat transfer. The higher obstacle position in Cases 6 and 7 leads to the small value of the average Nusselt number. Moreover, the effect of Ha on average Nu in Case 1 at [Formula: see text] is more significant than other cases because the flow pattern in Case 1 is changed as increasing Ha.

scholarly journals Numerical Study of MHD Natural Convection in Trapezoidal Enclosure Filled With (50%MgO-50%Ag/Water) Hybrid Nanofluid: Heated Sinusoidal from Below

2021 ◽  
Vol 39 (4) ◽  
pp. 1271-1279
Author(s):  
Mohammed Azeez Alomari ◽  
Khaled Al-Farhany ◽  
Alaa Liaq Hashem ◽  
Mohamed F. Al-Dawody ◽  
Fares Redouane ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Numerical Study ◽  
Working Fluid ◽  
Hybrid Nanofluid ◽  
Nusselt Numbers ◽  
Stream Functions ◽  
Trapezoidal Enclosure ◽  
Good Agreement

Numerical simulation of MHD free convection in a two-dimensional trapezoidal cavity of a hybrid nanofluid has been carried out in this research. The cavity is heated sinusoidal from the bottom wall, and the inclined walls are cooled while the top wall is isolated. The hybrid nanofluid (MgO-Ag/water) has been used as a working fluid. The numerical simulation has been validated with past papers and met a good agreement. The considered parameters are a range of Rayleigh number (Ra= 103 to 106), Hartmann number (Ha= 0 to 60) and volume fraction (f= 0 to 0.02). The results are presented as isotherms, stream functions, local and average Nusselt numbers, from which it is observed that the strength of the stream functions and isotherms increases with the increase of the Ra and ϕ while the increase in Hartmann number reduce the circulation of the flow and increases the isotherms strength. Also, the Nusselt number is increases with Ra and ϕ while it decreases with Ha.

Magnetic field impact on nanofluid convective flow in a vented trapezoidal cavity using Buongiorno's mathematical model

2019 ◽  
Vol 88 (1) ◽  
pp. 11101 ◽  
Author(s):  
Mahdi Benzema ◽  
Youb Khaled Benkahla ◽  
Ahlem Boudiaf ◽  
Sief-Eddine Ouyahia ◽  
Mohammed El Ganaoui
Keyword(s):  
Magnetic Field ◽  
Nusselt Number ◽  
Average Nusselt Number ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Numerical Study ◽  
Flow Behavior ◽  
Brownian Diffusion ◽  
High Concentration ◽  
Wide Range

Numerical study for the effect of an external magnetic field on the mixed convection of Al2O3–water Newtonian nanofluid in a right-angle vented trapezoidal cavity was performed using the finite volume method. The non-homogeneous Buongiorno model is applied for numerical description of the dynamic phenomena inside the cavity. The nanofluid, with low temperature and high concentration, enters the cavity through the upper open border, and is evacuated through opening placed at the right end of the bottom wall. The cavity is heated from the inclined wall, while the remainder walls are adiabatic and impermeable to both the base fluid and nanoparticles. After validation of the model, the analysis was carried out for a wide range of Hartmann number (0 ≼ Ha ≼ 100) and nanoparticles volume fraction (0 ≼ ϕ0 ≼ 0.06). The flow behavior as well as the temperature and nanoparticles distribution shows a particular sensitivity to the variations of both the Hartmann number and the nanofluid concentration. The domination of conduction mechanism at high Hartmann numbers reflects the significant effect of Brownian diffusion which tends to uniform the distribution of nanoparticles in the domain. The average Nusselt number which increases with the nanoparticles addition, depends strongly on the Hartmann number. Finally, a correlation predicting the average Nusselt number within such geometry as a function of the considered parameters is proposed.

Study of Entropy Generation and Magnetohydrodynamic (MHD) Natural Convection in a Curved Enclosure Having Various Amplitude and Filled with Cu–TiO2/Water Hybrid Nanofluid

2021 ◽  
Vol 10 (3) ◽  
pp. 339-354
Author(s):  
Rujda Parveen ◽  
Tapas Ray Mahapatra ◽  
B. C. Saha
Keyword(s):  
Rayleigh Number ◽  
Entropy Production ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Titanium Dioxide Nanoparticles ◽  
Temperature Fields ◽  
Model Parameters ◽  
Hybrid Nanofluid ◽  
Volume Percentage ◽  
Left Wall

We have studied the buoyancy-driven convection enhancement and entropy production in a Cu–TiO2/water (water with copper and titanium dioxide nanoparticles) hybrid nanofluid filled curved enclosure subjected to a uniform magnetic field. The enclosure has a sinusoidally heated right wall, cold left wall, uniformly heated bottom wall, and thermally insulated upper curved wall. The effect of different amplitudes (concave, square, and convex) of the upper curved wall is considered. The non-linear governing equations are non-dimensionalized and written in stream function-velocity formulation. Bi Conjugate Gradient Stabilized (BiCGStab) method is employed followed by a Tri-diagonal matrix algorithm (TDMA) for the numerical simulation. The considered parameters are as follows: Rayleigh number (Ra), Hartmann number (Ha), phase angle (ε), the amplitude of the curved wall (a), and nanoparticle volume fraction (Φ). The influence of the model parameters on entropy production, fluid flow, and heat transfer phenomenon has been investigated, and the simulated results are displayed in terms of flow fields and temperature fields. According to the studies, increasing the Rayleigh number and volume percentage of nanoparticles has a significant impact on heat transmission and hence dominates the convection effect, whereas increasing the Hartmann number has the opposite effect.

scholarly journals Numerical Study on the Natural Convection of Air in a Cubic Cavity Subjected to a Yawing Motion

2019 ◽  
Vol 7 (7) ◽  
pp. 204 ◽  
Author(s):  
Yu ◽  
Zhang ◽  
Jia ◽  
Geng ◽  
Liu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Numerical Study ◽  
Rotation Period ◽  
Rotation Frequency ◽  
Static Case ◽  
Governing Equations ◽  
Induced Velocity

Natural convections subjected to multi-Degree of Freedom (DoF) motion are much more complex than those in static case, and those subjected to yawing motion are the simplest and ideal case for investigating their characteristics due to less interactive parameters. In this paper, the characteristic of natural convection under yawing motion was studied systematically to clarify the interaction between yawing motion and thermal-dynamic behavior. First of all, the mathematical model was established in a non-inertial coordinate system, and the dimensionless governing equations were derived. Subsequently, the governing equations were discretized in the framework of the finite volume method, and a computer code was developed and validated. After that, the natural convection under yawing motion was calculated with different combinations of dimensionless parameters, and the influence of rotation frequency and amplitude on heat and mass transfer was investigated. It was found that the yawing motion plays a notable role in flow and heat transfer, depending on the relative magnitudes of rotation-induced velocity and buoyancy-induced velocity: At a lower Rayleigh number of 104, the Nusselt number on hot boundary is enhanced by approximately 25% when the rotation period is changed from 12 s to 2 s; while the changing in rotation period from 12 s to 2 s did not induce obvious difference in hot-boundary Nusselt number for a higher Rayleigh number of 105. It is concluded that the vertical-axis harmonic rotation enhances heat transfer if the rotation-induced velocity dominates the flow. The clarification of natural convection characteristic in yawing motion provides convenience for analyzing that in other multi-DoF systems.

scholarly journals Effect of Al2O3 Nanoparticles and Cylindrical Pins on Natural Convection Heat Transfer in a C-Shaped Enclosure

2020 ◽  
Vol 12 (4) ◽  
pp. 499-515
Author(s):  
M. Y. Arafat ◽  
F. Faisal
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Al2o3 Nanoparticles ◽  
Simpler Algorithm

A numerical study has been conducted to investigate the transport mechanism of natural convection in a C-shaped enclosure filled with water-Al2O3 nanofluid for various pertinent parameters. The effects of the volume fraction of the Al2O3 nanoparticles, Rayleigh number, and radius of inserted cylindrical pins on the temperature, velocity, heat flux profiles and average Nusselt number have been investigated. General correlations for the effective thermal conductivity and viscosity of nanofluids are used for this analysis. The governing mass, momentum and energy equations are solved numerically with the finite volume method using the SIMPLER algorithm. The results show that addition of nanoparticle improves the heat transfer performance. Insertion of cylindrical pins of lower radius increases the average Nusselt number irrespective of Rayleigh number. But anomaly has been observed while pins of higher radius are inserted due to enormous disturbance in the fluid.

Heat transfer characteristics of nanofluids from a sinusoidal corrugated cylinder placed in a square cavity

2021 ◽  
pp. 095440622110272
Author(s):  
Salaika Parvin ◽  
Nepal Chandra Roy ◽  
Litan Kumar Saha ◽  
Sadia Siddiqa
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Average Nusselt Number ◽  
Numerical Study ◽  
Heat Transfer Characteristics ◽  
Number Range ◽  
Transfer Characteristics ◽  
Wide Range

A numerical study is performed to investigate nanofluids' flow field and heat transfer characteristics between the domain bounded by a square and a wavy cylinder. The left and right walls of the cavity are at constant low temperature while its other adjacent walls are insulated. The convective phenomena take place due to the higher temperature of the inner corrugated surface. Super elliptic functions are used to transform the governing equations of the classical rectangular enclosure into a system of equations valid for concentric cylinders. The resulting equations are solved iteratively with the implicit finite difference method. Parametric results are presented in terms of streamlines, isotherms, local and average Nusselt numbers for a wide range of scaled parameters such as nanoparticles concentration, Rayleigh number, and aspect ratio. Several correlations have been deduced at the inner and outer surface of the cylinders for the average Nusselt number, which gives a good agreement when compared against the numerical results. The strength of the streamlines increases significantly due to an increase in the aspect ratio of the inner cylinder and the Rayleigh number. As the concentration of nanoparticles increases, the average Nusselt number at the internal and external cylinders becomes stronger. In addition, the average Nusselt number for the entire Rayleigh number range gets enhanced when plotted against the volume fraction of the nanofluid.

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