SNF - Multiphase fluid flow

The main goal of this research project is therefore to better understand non-isothermal multiphase flow in porous media, including phase change phenomena like crystallization and partial freezing using an integrated approach combining pore-scale and continuum models. In spite of many attempts and undeniable successes both theoretically and experimentally, yet the determination of multiphase interface configurations in complex pore geometries is not fully understood and it remains a challenging problem for researchers. The goal of the project will be achieved by developing validated pore-scale models to capture accurately the main physics of wetting, drying, crystallization processes in porous materials at pore-scale and then to upscale to the macro-scale for the assessment of multiphase flow and durability behaviour of porous materials in different applications. Specifically the project aims at filling the following research gaps: (1) further advancing validated non-isothermal lattice Boltzmann Models (LBM) at pore-scale for multiphase fluid transport within complex porous system including phase change like evaporation and crystallization; (2) coupling the LB model with pore-network models allowing upscaling for the determination of the macroscopic fluid transport properties; (3) at the macro-scale, further developing validated continuum models to study the heat and moisture performance of porous materials under partial freezing and to study the damage process under freeze-thaw cycling. With respect to partial freezing, we propose to couple a heat-moisture transport model for partial freezing to a poro-mechanical damage model. To validate the different models, special experiments will be conducted, which are based - apart from more classical measurements - on advanced imaging analysis of multiphase flow, crystallization and damage on pore and macro-scale.

The project is organized in three major workpackages involving 4 PhD students.

This systematic approach will open new frontiers in the understanding and control of multiphase flow in different porous systems with applications in different fields such as petroleum engineering, biology, geophysics, building physics, pharmaceutical, chemical and semiconductor industries. Of special interest is the evaluation of the impact of deformation of porous materials, such as crack closure, on the fluid transport properties such as permeability, which is of great importance in a lot of applications such as petroleum engineering and geophysics. The coupled transport and reaction of fluids in porous media or fractures plays also a crucial role in a variety of scientific, industrial, and engineering processes such as simulation of petroleum reservoirs, geologic carbon sequestration, environmental contaminate transport and degradation of concrete and building materials. Because of the effect of chemical reactions, geometrical properties of porous media such as porosity, fracture aperture and tortuosity may significantly modify which can lead to a strong influence on macro-scale properties such as permeability and effective moisture diffusivity. The developed models for multiphase flow in porous media will be in particular applied to dynamic wicking in textiles at yarn scale. The developed models will also be applied for assessing frost damage in porous materials, which is of great interest for a wide range of fields such as civil engineering, food engineering, biomechanics and geomorphology. In the project we will focus on the retrofit of historical buildings worth preserving their facade and accounting for about 20 % of the existing building stock in Switzerland, which can be vulnerable to frost damage.