Heat transfer through wavy clothing layers with varied permeability

• Heat transfer through air-permeable fabric in wavy and flat shapes was investigated. • Airflow parallel to fabric folds enhanced heat transfer more effectively than cross airflow. • Wavy fabric structures promoted heat transfer compared to flat configurations. • Air permeability showed a non-monotonic influence on heat transfer. The heat exchange between the human body and the environment is significantly influenced by the microclimate created between the clothing and the skin, which is essential for maintaining thermophysiological comfort. In the present study, a three-dimensional (3D) numerical model was developed to investigate heat transfer between the skin and the environment through wavy microclimate structures with different clothing permeability. The air penetration through the clothing was considered, and the clothing was treated as a porous and air-permeable material in the model. Viscous shear and inertial effects were included in the governing equations to accurately simulate airflow in the fabric domain. The numerical model was first validated against experimental data obtained from a sweating guarded hotplate and showed good agreement. The validated model was then used to study the effect of airflow direction on the heat transfer performance. The results showed that airflow parallel to the fabric folds enhances heat transfer compared to airflow perpendicular to the fabric folds. Additionally, the effects of the wavy fold aspect ratio (amplitude to wavelength, W/H=2.4, 4.8 and infinite) and fabric air permeability ( 10 − 14 m 2 to 10 − 6 m 2 ) were analyzed. The findings revealed that heat dissipation is more effective in wavy shapes than flat configurations. Moreover, heat flux decreased with increasing permeability until a critical minimum was reached, after which heat flux started to increase sharply. This research provides detailed insights into heat transfer in clothing microclimates, which is valuable for advancing clothing design.