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# Study of Laminar Forced Convection of Radiating Gas Over an Inclined Backward Facing Step Under Bleeding Condition Using the Blocked-Off Method

[+] Author and Article Information
A. B. Ansari1

Department of Mechanical Engineering, School of Engineering, Shahid Bahonar University, Kerman 76169-133, Iranaba2449@yahoo.com

S. A. Gandjalikhan Nassab

Department of Mechanical Engineering, School of Engineering, Shahid Bahonar University, Kerman 76169-133, Iranganj110@mail.uk.ac.ir

1

Corresponding author.

J. Heat Transfer 133(7), 072702 (Apr 05, 2011) (9 pages) doi:10.1115/1.4003607 History: Received November 02, 2010; Revised January 20, 2011; Published April 05, 2011; Online April 05, 2011

## Abstract

This paper presents a numerical investigation for laminar forced convection flow of a radiating gas over an inclined backward facing step in a horizontal duct subjected to bleeding condition. The fluid is treated as a gray, absorbing, emitting, and scattering medium. The two-dimensional Cartesian coordinate system is used to simulate flow over inclined surface by considering the blocked-off region in regular grid. The governing differential equations consisting the momentum and energy are solved numerically by the computational fluid dynamics techniques to obtain the velocity and temperature fields. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. Since the gas is considered as a radiating medium, convection, conduction, and radiation heat transfer mechanisms take place simultaneously in the gas flow. For computation of the radiative term in the gas energy equation, the radiative transfer equation is solved numerically by the discrete ordinate method to find the radiative heat flux distribution inside the radiating medium. The effects of bleeding coefficient, inclination angle, optical thickness, albedo coefficient, and the radiation-conduction parameter on the flow and temperature distributions are carried out.

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## Figures

Figure 3

Blocked-off region in a regular grid

Figure 4

Comparison of reattachment point

Figure 5

Distribution of convective Nusselt number along the bottom wall, Re=400

Figure 6

Variation of midplane temperature, RC=10, ε=1.0, and τ=1.0

Figure 7

Schematic of semicircular enclosure

Figure 8

Radiative heat flux distribution on the bottom wall

Figure 9

Stream lines contours, Re=500, ϕ=45 deg: (a) Ψ=0.0, (b) Ψ=−0.005, and (c) Ψ=+0.005

Figure 12

Effect of optical thickness on the fluid bulk temperature, RC=50, ω=0.5, Re=400, and Ψ=−0.005

Figure 13

Effect of bleeding coefficient on the total Nusselt number along the bottom wall, RC=50, ω=0.5, and τ=0.005

Figure 14

Effect of inclination angle on the Nusselt number distribution along the bottom wall, RC=50, ω=0.5, τ=0.005, and Ψ=−0.005

Figure 1

Sketch of problem geometry

Figure 2

A schematic of grid generation

Figure 10

Effect of RC on the Nusselt number distribution along the bottom wall, τ=0.005, ω=0.5, Re=400, Ψ=−0.005: (a) radiative and convective Nusselt number and (b) total Nusselt number

Figure 11

Effect of albedo on the total Nusselt number distribution along the bottom wall, RC=100, τ=0.005, Re=400, and Ψ=−0.005

## Errata

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