A Comprehensive Review of Nusselt Number Enhancement of Natural Convection in Literal Shapes Cavities: Recent Trends and Future Challenges

This research review analyzes a group of previous studies that focused on improving natural convection in literal-shaped cavities filled with base fluids (H2O or other), nanofluids, or hybrid nanofluids.This work attempts to provide an in-depth and integrated understanding of how the complex geometry of cavities affects the boosting of heat transfer and heat exchange efficiency.Highlighting the thermophysical properties of these different fluids.The current study sought to review the most prominent engineering applications and research challenges associated with this field.This study attempts to explore recent trends in improving thermal performance through the use of unconventional fluids, and to analyze various factors such as Raleigh number (Ra), Prandtl number (Pr), Volume Fraction (), viscosity, and thermal conductivity.Numerous studies have addressed natural convection in classical cavities, whereas complex cavities (such as U, V, C, L, E, H etc.) still need further study, which constitutes a scientific gap that can be explored.