CFD-driven design of a thermal foot manikin: Enhancing temperature uniformity and environmental adaptability for outdoor footwear comfort studies

This work presents a CFD-based thermal foot manikin to enhance temperature uniformity and adapt to varied environments for footwear assessment. A 3D-scanned anthropometric foot geometry was overlaid with custom heating elements. Transient calculations were achieved using the SST k-ω turbulence model. Simulations compared nine heater layouts, revealing that an optimized asymmetric distribution (2 W on the instep, 1 W on the forefoot, 2 W on the rear sole) minimized skin surface temperature range to 0.97 °C in simulation and 0.91 °C in physical trials under constant heat flux conditions. Subsequently, the prototype's adaptive control was evaluated in a climatic chamber operating in constant skin temperature mode. At 26 °C, temperature regulation precision reached ±0.073 °C. Under dry conditions, stabilization required 267.6 s and exhibited a variance of 0.0048 °C². Based on these findings, we recommend testing thermal insulation in a dry-nude configuration and evaporative resistance with a wet simulated skin, maintaining the manikin at 36 ± 0.2 °C. Finally, we define four performance metrics (Range_CHF (measured skin temperature range), CA (control accuracy), t_st (stabilization time), and STA (temperature variance after stabilization)) to improve reproducibility across thermal manikin studies.