Figure 4.

Surface temperature measured by Liu et al. [57] in a microtube of 44.2 µm inner diameter and 140 mm length at various Reynolds numbers. (a) $Re=0$; (b) $Re=297.2$; (c) $Re=491.8$; (d) $Re=692$. Temperatures for various locations in the channel are provided in °C in the left part of the image. Reprinted by permission from Ref. [57], Journal of Thermal Science, Copyright © 2022 Springer-Verlag.