The aim of this study is to investigate and improve heat transfer in a rectangular
channel with fluid flow. In this context, a backward-facing step (BFS) and harmonic
force-actuated flexible walls are used as effective factors for enhancing heat transfer
within the channel. These two mechanisms lead to an increase in flow mixing. The
primary focus of this research is to identify the optimal placement and excitation
pattern for the flexible wall in order to maximize heat transfer. To maintain laminar
flow conditions, the Reynolds number, defined using the height of the narrow
portion of the channel, is fixed at 1000. The analysis investigates heat transfer
characteristics, hydrodynamic friction factor, and overall hydrothermal efficiency
for different positions of the wall section and various excitation frequencies.
According to the results obtained, the combination of the backward-facing step and
oscillating wall can increase the heat transfer rate by up to 280% compared to a
channel that only uses the backward-facing step, while simultaneously reducing the
required input power by approximately 54.6% .This study also addresses the
challenges of increasing heat transfer while reducing pressure drop and friction,
providing optimization strategies for the system using simulation results and their
validation. Finally, by analyzing the impact of flexible vortex generators in the
channel with sudden expansion and the interaction between fluid and structure, the
study improves thermal system performance and reduces structural vibrations. The
results of this research can significantly contribute to the enhancement of the
efficiency of thermal systems, such as heat exchangers, power plants, HVAC
systems, electronic device cooling, and various industries, offering strategies for
optimizing thermal performance and reducing energy consumption in these areas.