Breathing from Underground: Diurnal Variability in the Ventilation Mechanism of Termite Mounds

Termites are social insects that build massive porous mounds for creating a habitable environment for their colony. These structures exhibit intricate architectures that can effectively harness natural wind, solar energy, and colony’s metabolic heat to produce controlled microclimates in termite nests. Based on experimental studies, several mechanisms have been proposed to explain the ventilation and gas exchange process in termite mounds, such as, metabolism-driven convection, the impact of external wind, and formation of thermal gradients due to diurnal variation of the mound surface temperature.
This study investigates the underlying physics of the ventilation mechanisms in termite mounds. Computational fluid dynamics (CFD) modeling is used to simulate flow past and through the porous bodies of termite mounds. For this purpose, the Navier–Stokes equations are modified in a Direct Numerical Simulation using the Darcy-Brinkman-Forchheimer model to represent the porosity. The effect of the diurnally variable surface temperatures is considered through the dynamic coupling of the CFD model with an energy balance-based model that simulates the spatiotemporally variable surface temperatures in high resolution.