Multi-scale three-domain approach for coupling free flow and flow in porous media including droplet-related interface processes

TL;DR

This paper introduces a multi-scale three-domain modeling approach to simulate droplet processes at free flow and porous media interfaces, capturing their effects on flow exchange with computational efficiency.

Contribution

It presents a novel three-domain framework incorporating droplet formation, growth, detachment, and film flow, with an upscaling technique for interface area fraction calculation.

Findings

Droplet processes significantly influence flow exchange.

The model effectively captures droplet formation, growth, and detachment.

Extensions are needed for more accurate free flow influence representation.

Abstract

Drops on a free-flow/porous-medium-flow interface have a strong influence on the exchange of mass, momentum and energy between the two macroscopic flow regimes. Modeling droplet-related pore-scale processes in a macro-scale context is challenging due to the scale gap, but might be rewarding due to relatively low computational costs. We develop a three-domain approach to model drop formation, growth, detachment and film flow in a lower-dimensional interface domain. A simple upscaling technique allows to compute the drop-covered interface area fraction which affects the coupling fluxes. In a first scenario, only drop formation, growth and detachment are taken into account. Then, spreading and merging due to lateral fluxes are considered as well. The simulation results show that the impact of these droplet-related processes can be captured. However, extensions are necessary to represent the influence on the free flow more precisely.