Stratification effects on flow and scalar transport through a deep cavity: A bioinspired examination

This study investigates the effect of thermal stratification and boundary layer wind on the transport phenomena within a deep cavity. The study is inspired by the ventilation and gas-exchange process within the chimneys of open-vent termite mounds. Large-eddy simulations are conducted over an idealized termite mound subject to different thermal stratifications that are formed based on the observed mean day and night-time air and mound nest temperatures reported in the literature. A thorough analysis of the flow, temperature, and scalar fields indicates that the dynamics of the flow and the ventilation process within the cavity are controlled by the combined effects of the cavity entrance vortex and the stability condition within the lower regions of the cavity. The results show that, despite the small differences in the imposed stratification condition, the ventilation capacity is significantly higher in unstable conditions, owing to the stronger suction at the cavity entrance, together with the positive buoyant forces at the lower sections of the cavity. The results are in agreement with experimental observations of termite mounds in nature.This study investigates the effect of thermal stratification and boundary layer wind on the transport phenomena within a deep cavity. The study is inspired by the ventilation and gas-exchange process within the chimneys of open-vent termite mounds. Large-eddy simulations are conducted over an idealized termite mound subject to different thermal stratifications that are formed based on the observed mean day and night-time air and mound nest temperatures reported in the literature. A thorough analysis of the flow, temperature, and scalar fields indicates that the dynamics of the flow and the ventilation process within the cavity are controlled by the combined effects of the cavity entrance vortex and the stability condition within the lower regions of the cavity. The results show that, despite the small differences in the imposed stratification condition, the ventilation capacity is significantly higher in unstable conditions, owing to the stronger suction at the cavity entrance, together with the positive ...