scholarly journals Mixed Convection in a Vented Square Cavity with a Heat Conducting Horizontal Solid Circular Cylinder

2009 ◽  
Vol 5 (2) ◽  
pp. 37-46 ◽  
Author(s):  
Mustafizur Rahman ◽  
M A Alim ◽  
Suman Saha ◽  
M K Chowdhury
Keyword(s):  
Heat Transfer ◽  
Finite Element Method ◽  
Finite Element ◽  
Circular Cylinder ◽  
Mixed Convection ◽  
Richardson Number ◽  
Heat Conducting ◽  
Square Cavity ◽  
Flow And Heat Transfer ◽  
Solid Circular Cylinder

A finite element method based computational study of steady laminar mixed convection flow inside a vented square cavity with a heat conducting horizontal solid circular cylinder placed at the center of the cavity is carried out in this paper. The developed mathematical model is governed by the coupled equations of continuity, momentum and energy. The present work simulates practical systems such as cooling of electronic devices, ventilation of building etc. The effects of cylinder size and Richardson number on fluid flow and heat transfer performance are investigated. Richardson number is varied from 0.0 to 5.0 and the cylinder diameter is varied from 0.0 to 0.6. The results for the case of without cylinder are compared to those with cylinder to observe the effects cylinder on the flow and heat transfer inside the cavity. The phenomenon inside the cavity for the case of with and without cylinder is analyzed through streamline and isotherm patterns. It is found that the streamlines, isotherms, average Nusselt number at the heated surface, average temperature of the fluid in the cavity and dimensionless temperature at the cylinder center strongly depend on the Richardson number as well as the diameter of the cylinder.Keywords: Mixed convection, finite element method, Richardson number, cylinder diameter, vented cavity and diffusion.DOI: 10.3329/jname.v5i2.2504Journal of Naval Architecture and Marine Engineering 5(2)(2008) 37-46

Influence of Shape of Nanoparticles on Nanofluid Hydrothermal Behavior

2018 ◽  
pp. 331-388
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Finite Element Method ◽  
Finite Element ◽  
Stream Function ◽  
Shape Factor ◽  
Control Volume ◽  
Flow And Heat Transfer ◽  
Shape Of Nanoparticles ◽  
Stream Function Formulation

The shape of nanoparticles can change the thermal conductivity of nanofluid. So, the effect of shape factor on nanofluid flow and heat transfer has been reported in this chapter. Governing equations are presented in vorticity stream function formulation. Control volume-based finite element method (CVFEM) is utilized to obtain the results. Results indicate that platelet shape has the highest rate of heat transfer.

Finite Element Simulation of Magnetohydrodynamic Mixed Convection in a Double-Lid Driven Enclosure With a Square Heat-Generating Block

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
M. M. Rahman ◽  
M. M. Billah ◽  
N. A. Rahim ◽  
R. Saidur ◽  
M. Hasanuzzaman
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Mixed Convection ◽  
Convection Flow ◽  
Weighted Residuals ◽  
Thermal Fields ◽  
Flow And Heat Transfer ◽  
Element Simulation ◽  
Wide Range ◽  
Element Technique

Magnetohydrodynamic (MHD) mixed-convection flow and heat transfer characteristics inside a square double-lid driven enclosure have been investigated in this study. A heat-generating solid square block is positioned at the centre of the enclosure. Both of its vertical walls are lid-driven and have temperature Tc and uniform velocity V0. In addition, the top and bottom surfaces are kept adiabatic. Discretization of governing equations is achieved using finite element technique based on Galerkin weighted residuals. The computation is carried out for a wide range of pertinent parameters such as Hartmann number, heat-generating parameter, and Richardson number. Numerical results are reported for the effects of aforesaid parameters on the streamline and isotherm contours. In addition, the heat transfer rate in terms of the average Nusselt number and temperature of the fluid as well as block center are presented for the mentioned parametric values. The obtained results show that the flow and thermal fields are influenced by the above-mentioned parameters.

Laminar Mixed Convection of Non-Newtonian Nanofluids Flowing Vertically Upward Across a Confined Circular Cylinder

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Abhipsit Kumar Singh ◽  
Nanda Kishore
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Circular Cylinder ◽  
Mixed Convection ◽  
Richardson Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Numerical Results ◽  
Total Drag ◽  
Drag Coefficients

Numerical results on laminar mixed convective heat transfer phenomenon between a confined circular cylinder and shear-thinning type nanofluids are presented. The cylinder is placed horizontally in a confined channel through which nanofluids flow vertically upward. The effect of buoyancy is same as the direction of the flow. Because of existence of mixed convection, governing continuity, momentum, and energy equations are simultaneously solved within the limitations of Boussinesq approximation. The ranges of parameters considered are: volume fraction of nanoparticles, ϕ = 0.005–0.045; Reynolds number, Re = 1–40; Richardson number, Ri = 0–40; and confinement ratio of circular cylinder, λ = 0.0625–0.5. Finally, the effects of these parameters on the streamlines, isotherm contours, individual and total drag coefficients, and local and average Nusselt numbers are thoroughly delineated. The individual and total drag coefficients decrease with the increasing both ϕ and Re; and/or with the decreasing both Ri and λ. The rate of heat transfer increases with the increasing Re, ϕ, Ri, and λ; however, at Re = 30–40, when ϕ > 0.005 and Ri < 2, the average Nusselt number decreases with the increasing Richardson number. Finally, correlations for the total drag coefficient and average Nusselt number are proposed as functions of pertinent dimensionless parameters on the basis of present numerical results.

scholarly journals Effects of Reynolds and Prandtl Number on Mixed Convection in an Octagonal Channel with a Heat-Generating Hollow Cylinder

2012 ◽  
Vol 4 (2) ◽  
pp. 337 ◽  
Author(s):  
S. Parvin ◽  
R. Nasrin
Keyword(s):  
Heat Transfer ◽  
Finite Element Method ◽  
Finite Element ◽  
Prandtl Number ◽  
Mixed Convection ◽  
Hollow Cylinder ◽  
Numerical Study ◽  
Vertical Channel ◽  
Fluid Temperature ◽  
Element Method

A numerical study has been executed to analyze the effects of Reynolds and Prandtl number on mixed convective flow and heat transfer characteristics inside an octagonal vertical channel in presence of a heat-generating hollow circular cylinder placed at the centre. All the walls of the octagon are considered to be adiabatic. Galerkin weighted residual finite element method is used to solve the governing equations of mass, momentum and energy. Results are presented in terms of streamlines, isotherms, the average Nusselt number and the maximum fluid temperature for different combinations of controlling parameters namely, Reynolds number, Prandtl number and Richardson number. The results indicate that the flow and thermal fields as well as the heat transfer rate and the maximum fluid temperature in the octagonal channel depend significantly on the mentioned parameters.Keywords: Heat-generation; Hollow cylinder; Octagonal channel; Mixed convection; Finite element method.© 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i2.8142   J. Sci. Res. 4 (2), 337-348 (2012)

scholarly journals Effect of Reynolds and Prandtl Numbers on Mixed Convection in an Obstructed Vented Cavity

2011 ◽  
Vol 3 (2) ◽  
pp. 271-281
Author(s):  
M. M. Rahman ◽  
M. M. Billah ◽  
M. A. Alim
Keyword(s):  
Heat Transfer ◽  
Finite Element Method ◽  
Reynolds Number ◽  
Finite Element ◽  
Free Convection ◽  
Prandtl Number ◽  
Mixed Convection ◽  
Forced Convection ◽  
Thermal Field ◽  
Heat Transfer Characteristics

A numerical investigation is conducted to analyze the steady flow and thermal fields as well as heat transfer characteristics in a vented square cavity with a built-in heat conducting horizontal solid circular obstruction. Hydrodynamic behavior, thermal characteristics and heat transfer results are obtained by solving the couple of Navier-Stokes and energy equations by using a weighted residuals Finite element method. The computation was made for different Reynolds number, Prandtl number ranging from 50 to 200 and from 0.71 to 7.1 at the three different convective regimes. Three different regimes are observed with increasing Ri: forced convection (with negligible free convection), mixed convection (comparable free and forced convection) and free convection dominated region (with higher free convection). The results are presented to show the effects of the Reynolds number, Prandtl number on flow pattern, thermal field and heat transfer characteristics at the three convective regimes. It is found that the flow and thermal field strongly depend on the Reynolds number, Prandtl number as well as Richardson number. As the Reynolds number and Prandtl number increase, the heat transfer rate increases but average fluid temperature in the cavity and temperature at the cylinder center decrease at the three convective regimes.Keywords: Mixed convection; Finite element method; Obstructed vented cavity; Prandtl number.© 2011 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi:10.3329/jsr.v3i2.4344                J. Sci. Res. 3 (2), 271-281 (2011)

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