Numerical investigation of entropy generation in laminar forced convection flow over inclined backward and forward facing steps in a duct under bleeding condition

Abstract

A numerical investigation of entropy generation in laminar forced convection of gas flow over a recess including two inclined backward and forward facing steps in a horizontal duct under bleeding condition is presented. For calculation of entropy generation from the second law of thermodynamics in a forced convection flow, the velocity and temperature distributions are primary needed. For this purpose, the 2-D Cartesian co-ordinate system is used to solve the governing equations which are 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 region method is employed to simulate the inclined surface. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. The numerical results are presented graphically and the effects of bleeding coefficient and recess length as the main parameters on the distributions of entropy generation number and Bejan number are investigated. Also, the effect of Reynolds number and bleeding coefficient on total entropy generation which shows the amount of flow irreversibilities is presented for two recess length. The use of present results in the design process of such thermal system would help the system attain the high performance during exploitation. Comparison of numerical results with the available data published in open literature shows a good consistency.

Numerical Analysis of Turbulent Forced Convection of Nanofluid Flow over a Heated Shallow Cavity

“…Figure 10 confirms that for high Reynolds number, the effect of nanoparticle type on average Nusselt number has a minor effect; the smallest values are obtained for the heavier particle, Ag. The analysis of the shape of this curve can confirm, at least qualitatively, that the evolution of Nusselt number versus the volume fraction of nanofluid is consistent with the numerical study of Atashafrooz and colleagues [22].…”

Analysis of Combined Radiation and Forced Convection Heat Transfer in 3D Laminar Flow over an Inclined Forward Facing Step

“…Based on the result of grid tests for obtaining the grid-independent solutions, six different meshes were used in the grid independence study. Numerical solutions are obtained iteratively such that iterations are terminated when sum of the absolute residuals is less than 4 …”

“…Consequently, it has been used in the benchmark investigations. There are many studies about laminar convection flow over BFS in a 2-D duct by several investigators [1]- [4]. Velocity measurements were reported for three-dimensional laminar separated airflow adjacent to a backward-facing step using twocomponent laser Doppler velocimeter by Armaly et al [5].…”

Analysis of turbulent flow and heat transfer over a double forward facing step with obstacles

“…It is found that the entrainment coefficients, for elliptical jet case had average values of 0.15 and 0.58. Atashafrooz et al [9] worked on entropy generation in laminar forced convection of gas flow over a recess including two inclined backward and forward facing steps in a horizontal duct under bleeding condition. Other related studies on forward facing step flow can be found in literature [10][11][12][13][14][15][16].…”