A numerical study on the buoyancy effect around slanted-pin fins mounted on a vertical plate (Part-II: Laminar mixed convection)

2019 ◽  
Vol 132 ◽  
pp. 565-576 ◽  
Author(s):  
Yeong Woong Oh ◽  
Yoon Suk Choi ◽  
Man Yeong Ha ◽  
June Kee Min
Keyword(s):  
Mixed Convection ◽  
Vertical Plate ◽  
Numerical Study ◽  
Buoyancy Effect ◽  
Laminar Mixed Convection ◽  
Pin Fins

Conjugate Mixed Convection With Surface Radiation From a Vertical Plate With a Discrete Heat Source

2000 ◽  
Vol 123 (4) ◽  
pp. 698-702 ◽  
Author(s):  
C. Gururaja Rao ◽  
C. Balaji ◽  
S. P. Venkateshan
Keyword(s):  
Friction Coefficient ◽  
Heat Source ◽  
Mixed Convection ◽  
Vertical Plate ◽  
Numerical Study ◽  
Surface Radiation ◽  
Large Set ◽  
Computational Domain ◽  
Laminar Mixed Convection ◽  
Discrete Heat Source

The results of a numerical study of the problem of two-dimensional, steady, incompressible, conjugate, laminar, mixed convection with surface radiation from a vertical plate with a flush-mounted discrete heat source are reported. The governing equations, written in vorticity-stream function form, are solved using a finite-volume based finite difference method. A hybrid grid system has been employed for discretization of the computational domain. The effects of (i) the magnitude and location of the heat source, (ii) the material and surface properties of the plate, and (iii) the free-stream velocity on both heat transfer and fluid flow have been studied. Based on a large set of (more than 550) numerical data, correlations have been developed for maximum and average non-dimensional plate temperatures and mean friction coefficient. A method for evaluating the forced convection mean friction coefficient component, which may be used in estimating the power input required for maintaining the flow, has been proposed.

scholarly journals Numerical study of developing laminar mixed convection in a heated annular duct with temperature dependent properties

2019 ◽  
Vol 23 (6 Part A) ◽  
pp. 3411-3423
Author(s):  
Meriem Khemici ◽  
Toufik Boufendi ◽  
Sofiane Touahri
Keyword(s):  
Mixed Convection ◽  
Physical Properties ◽  
Numerical Study ◽  
Outer Cylinder ◽  
Joule Effect ◽  
Laminar Mixed Convection ◽  
Model Equations ◽  
Temperature Dependent Properties ◽  
Energy Equations ◽  
Horizontal Cylinders

This study presents a numerical simulation of the 3-D laminar mixed convection between two concentric horizontal cylinders with physical properties which depend on temperature. The outer cylinder is subjected to an internal energy generated by the Joule effect whereas the inner cylinder is adiabatic. The flow and thermal fields are modeled by the continuity, momentum, and energy equations with appropriate initial and boundary conditions using a cylindrical co-ordinate system. The model equations are numerically solved by a finite volume method with a second order accurate spatiotemporal discretization. For the considered geometric, dynamic and thermal controlling parameters, it is found that the transverse flow is always the cause of the circumferential variation of the temperature and the physical properties of the fluid. The phenomenon of the temperature stratification is highlighted and the vortices obtained lead to an improvement in the heat transfer quantified by the increase in the number of Nusselt. The obtained axial Nusselt number increases with the increased of Grashof number which is proportional to the heat flux imposed at the surface of the outer cylinder.

Laminar Mixed Convection in the Entrance Region of a Helical Pipe

1999 ◽  
Author(s):  
B. Zheng ◽  
C. X. Lin ◽  
M. A. Ebadian
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Control Volume ◽  
Three Dimensional ◽  
Entrance Region ◽  
Temperature Fields ◽  
Uniform Structure ◽  
Buoyancy Effect ◽  
Laminar Mixed Convection ◽  
Helical Pipe

Abstract A fully elliptic numerical study is performed to investigate the buoyancy-affected, three-dimensional laminar flow and heat transfer in the entrance region of a helical pipe at a constant wall temperature. The Control Volume Method with second-order accuracy is used to numerically solve the three-dimensional fully elliptic governing equations for the problem. The O-type non-uniform structure grid system is adopted to discretize the computation domain (two complete turns of a helical pipe) in this study. The Bossinesq approximation is applied to deal with the buoyancy effect caused directly by density difference. The developments of flow and temperature fields, profiles and characteristics at different Gr/Re2 are given and discussed. The computed results reveal that the entrance region of heat transfer is increased rapidly when buoyancy force is considered. In the meantime, the buoyancy effect on the average Nusselt number and friction factor is greater at the entrance region of the helical pipe, but it gradually becomes weaker further downstream.

Buoyancy Effect on the Wake of a Confined Circular Cylinder during Opposing Laminar Mixed Convection Heat Transfer

2013 ◽  
Vol 390 ◽  
pp. 675-679
Author(s):  
Iván Guillén ◽  
Cesar Treviño ◽  
Lorenzo Martínez-Suástegui
Keyword(s):  
Circular Cylinder ◽  
Mixed Convection ◽  
Richardson Number ◽  
Water Channel ◽  
Convection Heat Transfer ◽  
Buoyancy Effect ◽  
Piv Measurements ◽  
Laminar Mixed Convection ◽  
Image Velocimetry ◽  
Mixed Convection Heat Transfer

Particle image velocimetry (PIV) measurements are carried out in an experimental investigation of transient laminar opposing mixed convection to assess the thermal effects on the wake of an isothermal circular cylinder placed horizontally and confined inside a vertical closed-loop downward rectangular water channel. The buoyancy effect on the flow distributions are revealed for flow conditions with Reynolds number based on cylinder diameter of Re=170, blockage ratio D/H=0.287, aspect ratio, L/D=6.97 and values of the buoyancy parameter (Richardson number) of Ri=0 and 1. Results show that the wake closure length and Strouhal number slightly decrease for increasing Richardson number.

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