Numerical Investigation of 2-D Free Convection of Nanofluid in L-Shaped Enclosure

2013 ◽  
Vol 315 ◽  
pp. 433-437
Author(s):  
Nor Azwadi Che Sidik ◽  
Arman Safdari
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Rayleigh Number ◽  
Free Convection ◽  
Transfer Rate ◽  
Flow Behavior ◽  
Numerical Investigations ◽  
Flow And Heat Transfer ◽  
Vertical Walls ◽  
Higher Temperature

This paper presents numerical investigations of the thermal and fluid flow behavior in an L-shaped of cavity filled with nanofluid. The left and bottom walls are heated to higher temperature than the horizontal upper and right vertical walls. The results show that the characteristic of flow and heat transfer are critically dependent on the dimensionless Rayleigh number. We also found that the presence of nanoparticle enhances the heat transfer rate in the enclosure.

Numerical Investigation of Natural Convection of Nanofluids in L-Shaped Enclosures

2013 ◽  
Vol 849 ◽  
pp. 391-396
Author(s):  
Nor Azwadi Che Sidik ◽  
Arman Safdari
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Transfer Rate ◽  
Flow Behavior ◽  
Cu Nanoparticles ◽  
Numerical Investigations ◽  
Flow And Heat Transfer ◽  
Water Based

This paper presents numerical investigations of the thermal and fluid flow behavior in an L-shaped of cavity filled with nanofluid. For this purpose, five different water based Cu nanoparticles were selected with concentration of 1%, 3% and 5% were used. Effects of the presence of nanoparticles on the thermal and fluid flow in the enclosure were investigated in different Rayleigh number (Ra = 103, 104 and 105). Results show that the characteristic of flow and heat transfer are mainly dependent on the dimensionless Rayleigh number. We also found that the presence of nanoparticle enhances the heat transfer rate in the enclosure.

Free convection in the tilted open thermosyphon

1960 ◽  
Vol 7 (1) ◽  
pp. 115-127 ◽  
Author(s):  
F. M. Leslie
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Fluid Flow ◽  
Rayleigh Number ◽  
Free Convection ◽  
Small Angle ◽  
Approximate Solutions ◽  
Heated Cylinder ◽  
Flow And Heat Transfer ◽  
Large Rayleigh Number

Approximate solutions are found for the fluid flow and heat transfer in a heated cylinder, closed at the bottom and opening at the top into a reservoir of cool fluid, which has been tilted at a small angle to the vertical.One solution is found for large Rayleigh number when the boundary layer does not fill the tube, and another for small Rayleigh number when the boundary layer fills the tube. In both cases tilting causes a small increase in heat transfer which is proportional to the square of (l/a) tan ϕ, where l/a is the length–radius ratio and ϕ the angle of tilt.

Thermofluid Characteristics on Natural and Mixed Convection Heat Transfer From a Vertical Rotating Hollow Cylinder Immersed in Air: A Numerical Exercise

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Basanta Kumar Rana ◽  
Bhajneet Singh ◽  
Jnana Ranjan Senapati
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Mixed Convection ◽  
Hollow Cylinder ◽  
Vertical Cylinder ◽  
Cylinder Wall ◽  
Flow And Heat Transfer

Abstract Numerical investigations are performed on natural and mixed convection around stationary and rotating vertical heated hollow cylinder with negligible wall thickness suspended in the air. The fluid flow and heat transfer characterization around the hollow cylinder are obtained by varying the following parameters, namely, Rayleigh number (Ra), Reynolds number (ReD), and cylindrical aspect ratio (L/D). The heat transfer quantities are estimated by varying the Rayleigh number (Ra) from 104 to 108 and aspect ratio (L/D) ranging from 1 to 20. Steady mixed convection with active rotation of hollow vertical cylinder is further studied by varying the Reynolds number (ReD) from 0 to 2100. The velocity vectors and temperature contours are shown in order to understand the fluid flow and heat transfer around the vertical hollow cylinder for both rotating and nonrotating cases. The surface average Nusselt number trends are presented for various instances of Ra, ReD, and L/D and found out that the higher rate of heat loss from the cylinder wall occurs at high Ra, low L/D (short cylinder) and high ReD.

Numerical analysis of free convection and entropy generation in a cavity using compact finite-difference lattice Boltzmann method

2019 ◽  
Vol 30 (2) ◽  
pp. 977-995 ◽  
Author(s):  
HamidReza KhakRah ◽  
Payam Hooshmand ◽  
David Ross ◽  
Meysam Jamshidian
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Finite Difference ◽  
Free Convection ◽  
Lattice Boltzmann Method ◽  
Entropy Generation ◽  
Lattice Boltzmann ◽  
Content Type ◽  
Flow And Heat Transfer ◽  
Boltzmann Method

Purpose The purpose of this paper is to investigate the compact finite-difference lattice Boltzmann method is used to simulate the free convection within a cavity. Design/methodology/approach The finite-difference discretization method enables the numerical simulations to be run when there are non-uniform and curvilinear grids with a finer near-wall grid resolution. Furthermore, the high-order method is applied in the numerical approach, which makes it possible to go with relatively coarse mesh in respect to simulations, which used classical lattice Boltzmann method. The configuration of the cavity is set to sine-walled square. In addition, the cavity is filled with Al2O3-water nanofluid, and the Koo–Kleinstreuer–Li model is used to estimate the properties of nanofluid. Findings The nanoparticle (Al2O3) concentration in the base fluid (water) is considered in a range of 0-0.04. The nanofluid flow and heat transfer are investigated in laminar regime with Rayleigh number in the range of 103-106. The second law analysis is used to study the effects of different governing parameters on the local and volumetric entropy generation. The Rayleigh number, configuration of the cavity and nanoparticle concentration are considered as the governing parameters. The results are mainly focused on the flow structure, temperature field, local and volumetric entropy generation and heat transfer performance. Originality/value The originality of this study is using of a modern numerical method supported by an accurate prediction for nanofluid properties to simulate the flow and heat transfer during natural convection in a cavity.

scholarly journals Numerical study of natural melt convection in cylindrical cavity with hot walls and cold bottom sink

2013 ◽  
Vol 17 (3) ◽  
pp. 853-864 ◽  
Author(s):  
Abdennacer Ahmanache ◽  
Noureddine Zeraibi
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Cylindrical Cavity ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Bulk Temperature ◽  
Flow And Heat Transfer

Numerical study of natural convection heat transfer and fluid flow in cylindrical cavity with hot walls and cold sink is conducted. Calculations are performed in terms of the cavity aspect ratio, the heat exchanger length and the thermo physical properties expressed via the Prandtl number and the Rayleigh number. Results are presented in the form of isotherms, streamlines, average Nusselt number and average bulk temperature for a range of Rayleigh number up to 106. It is observed that Rayleigh number and heat exchanger length influences fluid flow and heat transfer, whereas the cavity aspect ratio has no significant effects.

scholarly journals Effect of Fin Length and Location on Natural Convection Heat Transfer in a Wavy Cavity

2020 ◽  
Vol 7 (3) ◽  
Author(s):  
M. Fayz-Al-Asad ◽  
M. J. H. Munshi ◽  
M.M.A. Sarker
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Flow Structure ◽  
Model Parameters ◽  
Flow And Heat Transfer ◽  
Wavy Cavity ◽  
Fin Length

The present study aims to analyze the natural convection flow and heat transfer in a wavy cavity with a single horizontal fin attached to its hot wall. Galerkin weighted residual finite element technique has been employed to solve the governing nonlinear dimensionless equations. The effects of model parameters like Rayleigh number, fin length and location on the fluid flow and heat transfer are investigated. The obtained results are exhibited graphically in terms of flow structure, temperature dispersion, velocity field, fin effectiveness, local Nusselt number, and average Nusselt number. It is observed that the different fin length and location have a substantial effect on flow structure and temperature field. Fin effectiveness is also studied and the highest fin effectiveness was found at fin length (L = 0.75). Besides, it is also found that the mean Nusselt number increases significantly with the increase of Rayleigh number and fin length. Wavy cavity becomes more effective on heat transfer behaviors and fluid flow than that of a square cavity.

scholarly journals Effects of Rotation on Transient Fluid Flow and Heat Transfer Through a Curved Square Duct: The Case of Negative Rotation

2021 ◽  
Vol 26 (4) ◽  
pp. 29-50
Author(s):  
Mohammad Sanjeed Hasan ◽  
Md. Tusher Mollah ◽  
Dipankar Kumar ◽  
Rabindra Nath Mondal ◽  
Giulio Lorenzini
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Secondary Flow ◽  
Flow Behavior ◽  
Square Duct ◽  
Curvature Effects ◽  
Flow And Heat Transfer ◽  
Curved Duct ◽  
Wide Range ◽  
Mechanical Devices

Abstract The fluid flow and heat transfer through a rotating curved duct has received much attention in recent years because of vast applications in mechanical devices. It is noticed that there occur two different types of rotations in a rotating curved duct such as positive and negative rotation. The positive rotation through the curved duct is widely investigated while the investigation on the negative rotation is rarely available. The paper investigates the influence of negative rotation for a wide range of Taylor number (−10 ≤ Tr ≤ −2500) when the duct itself rotates about the center of curvature. Due to the rotation, three types of forces including Coriolis, centrifugal, and buoyancy forces are generated. The study focuses and explains the combined effect of these forces on the fluid flow in details. First, the linear stability of the steady solution is performed. An unsteady solution is then obtained by time-evolution calculation and flow transition is determined by calculating phase space and power spectrum. When Tr is raised in the negative direction, the flow behavior shows different flow instabilities including steady-state, periodic, multi-periodic, and chaotic oscillations. Furthermore, the pattern variations of axial and secondary flow velocity and isotherms are obtained, and it is found that there is a strong interaction between the flow velocities and the isotherms. Then temperature gradients are calculated which show that the fluid mixing and the acts of secondary flow have a strong influence on heat transfer in the fluid. Diagrams of unsteady flow and vortex structure are further sketched and precisely elucidate the curvature effects on unsteady fluid flow. Finally, a comparison between the numerical and experimental data is discussed which demonstrates that both data coincide with each other.

Study of mixed convection in closed enclosure with a ceiling fan

2019 ◽  
Vol 86 (2) ◽  
pp. 20902 ◽  
Author(s):  
Lyes Nasseri ◽  
Omar Rahli ◽  
Djamel Eddine Ameziani ◽  
Rachid Bennacer
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Rayleigh Number ◽  
Lattice Boltzmann ◽  
Transfer Rate ◽  
Numerical Study ◽  
Square Cavity ◽  
Flow Intensity ◽  
Vertical Walls ◽  
Boltzmann Method

This paper presents a numerical study of heat transfer by convection in a square cavity. The vertical walls of the cavity are differentially heated and the horizontal ones are considered adiabatic. A fan is placed in the middle of the cavity and releases a jet down. Numerical simulation was performed using the lattice Boltzmann method to show the flow patterns and the heat flux depending on the Rayleigh number (thermal convection intensity) and the Reynolds number (fan-driven flow intensity). A parametric study was performed presenting the influence of Reynolds number (20 ≤ Re ≤ 500), Rayleigh number (10 ≤ Ra ≤ 106) and the fan position (0.2 ≤ HF ≤ 0.8). In forced convection mode, the flow structure has been mapped according to the position and the power of the fan. Three structures have emerged: two symmetrical cells, four symmetrical cells and asymmetrical structure. It has been observed that the heat transfer rate increases with the rise of Reynolds number and the reduction of the distance of the fan position from the ceiling. For the latter one, an unfavorable evolution of Nusselt number is observed for Ra > 104.

Sign in / Sign up

Export Citation Format

Share Document