Simulation of three-dimensional laminar forced convection flow of a radiating gas over an inclined backward-facing step in a duct under bleeding condition

Abstract

This study presents a numerical analysis of three-dimensional laminar forced convection flow of a radiating gas over an inclined backward-facing step in a rectangular duct under bleeding condition. The fluid is treated as a gray, absorbing, emitting, and scattering medium. The three-dimensional Cartesian coordinate system is used to solve the governing equations which are the conservations of mass, momentum, and energy. These equations are solved numerically using the computational fluid dynamic techniques to obtain the temperature and velocity fields, while the blocked-off method is employed to simulate the incline surface. 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, besides the convective and conductive terms in the energy equation, the radiative term also presented. For computation of this term, the radiative transfer equation is solved numerically by the discrete ordinates method to find the divergence of radiative heat flux distribution inside the radiating medium. By this numerical procedure, the role of radiation heat transfer on convection flow of a radiating gas which has many engineering applications (for example in heat exchangers and combustion chambers) is studied in detail. Beside, the effects of bleeding coefficient, albedo coefficient, optical thickness, and the radiation-conduction parameter on heat transfer behavior of the system are investigated. Comparison of numerical results with the available data published in the open literature shows a good agreement.

The Co-Processing Combustion Characteristics of Municipal Sludge within an Industrial Cement Decomposition Furnace via Computational Fluid Dynamics

“…The albedo coefficient, optical thickness, and radiation-conduction parameters have an influence on the heat transfer behavior of the system [23,24]. Among the six radiation models provided by Fluent, only the P1 model and DO (discrete ordinate) model can be used to simulate the radiation between the solid phase and gas phase.…”

The Effects of Buoyancy Force on the Irreversibility of Three-Dimensional Step Flow in an Inclined Duct

“… An optimum grid of 460×40×60 is considered to solve the governing equations according to the results of grid independence study, when the blocked off method is applied to simulate the surfaces of inclined step (Atashafrooz and Gandjalikhan Nassab 2012). Also, the calculations time with this grid is about 520 min using a personal computer Intel (R), Core(TM) i5, CPU 2.53 GHz and 4.00 GB of RAM.…”

“…This continued attention is actually due to the important influence of this type of flow in the design of many engineering equipment, such as combustion chambers, power generating equipment, cooling of electronic systems, and heat exchangers. In fact, the step flow has the most specifications of separation flows and is considered as benchmark geometry (Chen et al 2006, Atashafrooz and Gandjalikhan Nassab 2012, Mohammed et al 2015.…”