09. Heat and Mass Transfer

The temperature difference between the forehead surface and prefrontal cortex (PFC) was examined from thermo- and fluid-dynamics viewpoints, with a particular focus on impacts of walking on the forehead temperature, which is especially important for fever screening in airports and other public places. Forehead surface temperatures at rest and during walking were measured using a thermocouple glued on the forehead surface, and PFC temperatures were measured using a zero-heat-flux, core-temperature-monitoring probe. The forehead surface temperature during walking was dominantly controlled by heat transfer due to forced convection on the forehead surface, unlike in the case at rest in which free convection along the forehead surface as well as thermal radiation equally contributed to the heat transfer. The forced convection caused the forehead surface temperature to decrease appreciably with increasing the walking time until a steady state in the heat conduction inside the forehead was attained after walking 5 minutes or more, depending on the temperature difference between the forehead surface and environment. Such an impact of walking on the forehead temperature was well predicted by a one-dimensional heat transfer model assuming that the local forced convection heat flux on the midspan of the forehead was represented by that at the forward stagnation point of a heated circular cylinder immersed in a uniform flow.