Course description :
This unit specifically targets the media unsaturated in fluids that may show complex interfaces and contrasts between low and high frequency processes, as is the case for instance in the vadose zone between the atmospheric compartment and the aquifer. The introduction to multi-phase flow is limited to the simplified case air – water. A more descriptive part on soils and the vadose zone is also proposed and put emphasis on measures that allow for the identification of soil hydraulic properties. One also raises the complexity of the soil as a reactor including the role of the biotic compartment. Finally, a few elements of modeling complex transfers are also provided with the idea of simplifying the complexity and evaluate various fluxes.
Physics of the system
- Basics in physics of soils.
- Measurements of hydrodynamic parameters in a partially water saturated system. Infiltration tests, Capillary curves, state equations linking capillary pressure, water content and relative permeability.
- Flow in the simplified two phase system air + water with the assumption of infinite mobility of the air phase. Evolution of the systems with two phases showing finite mobility.
Soils, vadose zone, transient reactors
- Soil geometry, depiction of the phases.
- Macro-biologic compartment and bioturbations
- Reactions in soils and close to root hair: speciation of metals, catalytic redox reactions, auto-catalytic reactions, osmotic effects, capillary "lifter".
- Microbiologic compartment, bacterial growth, role of biofilms.
- Multiple porosity systems (including porous fractured media and porous media colonized by biofilms and their homogenized representation)
- Transport of particles. Inertial effects, electric, electrostatic and electromagnetic effects in the migration and retention mechanism.
- Multi-component reactive transport. Canonical decomposition in primary components and secondary species. Simplifications of the chemical systems and formalisms for their numerical resolution.