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 two-dimensional Cartesian coordinate
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.