SFB 1313 doctoral researcher Katharin Heck successfully defended her doctoral thesis "Modelling and analysis of multicomponent transport at the interface between free- and porous-medium flow - influenced by radiation and roughness" on 17 December 2020. Katharina Heck is a doctoral researcher at the Department of Hydromechanics and Modelling of Hydrosystems and a member of SFB 1313. She wrote her thesis within SFB 1313's Integrated Research Training Group IRTG-IMPM. Due to the present Corona-restrictions, only the examination committee could attend the talk which was broadcasted via Webex for the general public.
Quantifying evaporation rates and the emission of greenhouse gases from soil plays an important role in predicting changing climate conditions worldwide. Natural and anthropogenic sources of carbon dioxide and methane in soil, e.g. landfills, lead to the migration of these gaseous components in the subsurface and into the atmosphere.
The complexity of predicting emissions of these greenhouse gases from the soil into the atmosphere is high, as not only processes in the porous medium influence the transport, but also the ambient atmospheric conditions like wind velocities or solar radiation have a substantial influence on the exchange processes.
In order to analyse the governing processes and add to the fundamental understanding of coupled porous-medium free-flow processes, this work uses and further develops a numerical model that is able to describe mass, momentum, and energy transfer between a porous medium and an adjacent free flow. Multicomponent diffusion is described by the Maxwell-Stefan formulation and the effects of the presence of multiple components on the exchange process between the soil and atmosphere is analysed. Dominating transport processes are investigated with the help of various set-ups, including non-planar surfaces and different soil types. The influence of a diurnal cycle of solar radiation on evaporation, surface temperatures and the emission of greenhouse gases is discussed and a comparison of modelled evaporation rates with experimental data is analysed.