Effect of wind turbulence on gas transport in porous media: experimental method and preliminary results

Abstract

We demonstrate a novel experimental arrangement for measuring wind turbulence‐induced gas transport in dry porous media under controlled conditions. This equipment was applied to assess the effect of wind turbulence on gas transport (quantified as a dispersion coefficient) as a function of distance to the surface of the porous medium exposed to wind. Two different strategies for the measurement of wind‐induced gas transport were compared. Experiments were carried out with O2 and CO2 as tracer gases with average vertical wind speeds of 0.02–1.06 m s−1. Oxygen breakthrough curves as a function of distance to the wind‐exposed surface of the porous medium were analysed numerically with a finite‐difference‐based model to assess gas transport. We showed that wind turbulence‐induced gas transport is an important transport mechanism that can be 20–70 times larger than molecular diffusion‐induced transport. Wind conditions and properties of the porous medium had strong controlling effects on this relationship. Importantly, we show that even though wind‐induced gas transport is greatest near to the wind‐exposed surface, it can have marked effects on the variation in gas concentration at much greater depths.Highlights We explored the effect of atmospheric wind turbulence on gas transport in porous media. We measured the depth relation of wind‐induced dispersion in porous media for real wind conditions. Wind‐induced gas dispersion coefficients were 20–70 times larger than molecular diffusion. Wind turbulence can potentially have a considerable effect on gas transport in porous media.