Numerical simulations provide details on the ventilation mechanism of termite mounds
Numerical simulations provide details on the ventilation mechanism of termite mounds lead image
Several termites’ species build complex mounds for survival. Some of these structures include open chimneys, which provide ventilation with the diurnal cycle. To assess this natural ventilation and the respiratory gas transport within termite mounds, Saurabh Saxena and Neda Yaghoobian developed a computational framework and studied the effects of wind and temperature gradients in average daytime and nighttime conditions to investigate this fluid transportation.
Saxena and Yaghoobian found the primary contributors to the ventilation are the cavity entrance vortex and the temperature gradient within the cavity. The entrance vortex, determined by the external wind, impacts the pressure gradient and, thus, the suction at the top of the cavity. The temperature gradient deeper within the chimney determines the general chimney’s ventilation efficiency. Despite only small differences in the daytime and nighttime conditions, the ventilation capacity of the chimney during the day is over twice that at night.
The authors studied these parameters by modeling open-vent termite mounds as a Gaussian structure containing a vertical deep cavity. They applied near-ground atmospheric day and night wind conditions in their simulations to examine the ventilation under various thermal conditions.
“This research, through detailed computational modeling, sheds new light on the debated ventilation mechanism of termite mounds,” Yaghoobian said. She noted understanding these transport phenomena can also help improve energy efficiency in human structures. Additionally, she said these results have applications to other transport phenomena in similar natural structures, such as pollution ventilation in deep urban canyons.
Source: “Stratification effects on flow and scalar transport through a deep cavity: A bioinspired examination,” by Saurabh Saxena and Neda Yaghoobian, Physics of Fluids (2020). The article can be accessed at https://doi.org/10.1063/1.5134096 .
