5. Optimal process
In present study, the maximum values of thermal-hydraulic
performance factor (j/f) are achieved through optimized parameter
values of Reynolds number, to improve the heat transfer
performance accompanied by diminished pressure drop. In
addition, the minimum values of Nusselt number are found through
optimized parameter values of amplitude of the wavy wall, to
detect the critical amplitudes and the worst circumstances which
should be prevented in designing procedure. For optimization
process, a very recent method named Artificial Bee Colony (ABC)
algorithm was applied in this study. Also, a very well-known
method named particle swarm optimization (PSO) is employed to
validate ABC's results. It is worth mentioning that several runs for
each case were assigned to ensure the accuracy of the results.
6. Results and discussion
Fig. 5 demonstrates the effects of wavy wall amplitude and
Reynolds number on the average Nusselt number of the wavy wall.
By increasing the Reynolds number, average Nusselt number
increases. It can be noted that high velocity of the flow in the
converging section of the wavy wall increases the heat transfer.
Although, because of the swirl zones in diverging area, heat transfer
decreases, but the average Nusselt number is more influenced by
the high velocity flow of higher Reynolds numbers. Another