Numerical study of the convective heat transfer coefficient of the hand and the effect of wind

A 3D multi-segment thermoregulation model of the hand with realistic anatomy: Development, validation, and parametric analysis

“…Eq. 13 The corresponding values for and can be found in reference [40]. For wind speed larger than 2.0 m/s, was determined by [53] ⁄ Eq.…”

“…The radiative heat loss from the skin is given by ( ) Eq. 17 where (W/m 2 ) is the heat loss from the skin surface by radiation, is the view factor of each hand segment (see Table 5) obtained based on a previous study [40], the emissivity of the skin J o u r n a l P r e -p r o o f (a constant value of 0.95 is assumed in this study), the Stefan-Boltzmann constant (5.67×10 -8 W/(m 2 •K 4 )), and (K) the mean radiant temperature assumed to be equal to [42].…”

“…The thumb was omitted as it does not have a middle segment. The wind speed for all other hand segments was assumed to be 0.05 m/s, and the corresponding convective heat transfer coefficients were obtained from the literature [40].…”

“…The heat transfer J o u r n a l P r e -p r o o f coefficients, , they used for the bare finger were 7.02 W/m 2 •K and 9.46 W/m 2 •K for the circumferential surface and the fingertip, respectively; in our model, we assigned those same values to the middle segment of the middle finger and its fingertip, respectively. Using a previously developed model for calculating [40], we were able to derive the wind speed that corresponds to the above values: about 0.15 m/s. Based on this result, we used the model from [40] to calculate for the remaining hand segments.…”

“…There is a limited number of existing models that address differences in physiological responses [38] between hands and fingers or realistic dimensions of the hand [39]. The anatomical heterogeneity and the diverse geometry of the hand, which significantly affects the heat transfer coefficients [40] and the hand temperature profiles [41], are not usually taken into consideration in both whole hand and single finger models. Failure to simulate local differences in the thermo-physiological hand response makes it impossible to accurately predict temperatures of all fingers, present a temperature profile of the entire hand, as well as provide essential information for hand protection [42].…”