  This work proposes an extensive review of laminar and turbulent forced
convective heat transfer correlations inside tubes by analyzing both
experimental and computational research. Convective heat transfer is influenced
by fluid turbulence and boundary layers, with geometry significantly impacting
flow conditions. Nusselt number correlations quantifying the heat transfer
coefficient are vital for various applications. Previous reviews are summarized
regarding nanofluid heat transfer modeling approaches in circular tubes.
Additionally, comparisons of tube shapes like circular, elliptical and flat
geometries are needed. Recent database searches indicate more experimental than
numerical studies have been conducted, with greater focus on turbulent flows.
This review systematically evaluates laminar and turbulent forced heat transfer
correlations reported in the open literature, discussing both older established
work as well as newer findings to provide a holistic perspective. The goal is
to better understand convective transportation dependencies for optimized
thermal design and performance improvement.
