A Numerical Study on the Heat Loss from Clothed Humans —Effects of Air Space and Clothing Properties

Abstract

This paper presents a numerical model of heat transfer and fluid flow in the air space formed between the human body (modeled as a horizontal cylinder) and clothing (modeled as porous media). Factors that affect heat transfer and fluid flow in the air space are the thickness of the space between the body and clothing, and properties of the clothing, such as porosity or air flow resistance. Several clothing parameters are used to approximate various types of fabric. A critical air-space thickness at which the clothing retains the most heat was identified and found to be a function of the environmental temperature. The simulation results showed that the porosity of the clothing had little effect on the heat transfer. As the air flow resistance of the clothing decreased, the heat flux from the body increased. An approximate formula for the mean Nusselt number of a clothed human body was determined. The results showed that a circulating flow was present in the air space.