Variational finite element approach to study heat transfer in the biological tissues of premature infants

A mathematical model to study thermoregulation and heat-transfer processes in hypothermic neonates under variable physiological parameters

All neonates, whether term or preterm, are prone to hypothermia, which is a major health issue causing many health problems to infants and sometimes even death. Thus, such subjects are imperative to study to help researchers and biologists in neonatology, for developing certain methods, procedures and devices to prevent these abnormal temperature fluctuations to save the neonates from this health threat. To this purpose, a multi-node mathematical model is developed, to provide detailed insights and its applications to study the temperature profiles, thermoregulatory and heat-transfer mechanisms in hypothermic neonates. The model is constructed using the radial form of heat equation along with appropriate boundary and initial conditions. The model solution is obtained with the aid of the variational finite element method followed by the fundamental matrix method. The model outcomes obtained show the temperature fluctuations and tissue responses in hypothermic neonates. Finally, the model outcomes are compared with the published/experimental work to prove the feasibility and validity of the proposed work. Moreover, this work generalizes the several previously published works in the related field.

Numerical investigation of the convective heat transfer coefficient for a sleeping infant in a ventilation room

This study aimed to investigate the influence of wind speed and direction on the convective heat transfer from a sleeping infant in different postures. A computational fluid dynamics (CFD) model of a virtual infant manikin with realistic dimensions was developed to obtain the convective heat transfer coefficient (h_c ) at the body surface and the airflow and temperature distributions. The numerical model was validated beforehand using experimental data collected from infant thermal manikin experiments. The simulation results revealed that the infant's whole-body h_c increased from 4.00 to 15.73 W/m² ·K when wind speed varied from 0.12 to 1 m/s. Infants lost heat more quickly than adults under ventilation, with about 2 W/m² ·K higher h_c than adults in still air, and the discrepancy widened as the wind speed increased. Wind from the floor generated the highest h_c , approximately 66.4% greater than the wind from the feet at 1 m/s wind speed. Considering the wind from the feet caused the most evenly distributed h_c , ventilation equipment was suggested to be placed on the side of the infant's feet to reduce local discomfort. Based on the simulation results, empirical models of h_c were developed, which lay a solid theoretical foundation for further study on the interaction between infants and environments.