Laurent Orgogozo

Upscaling of transport processes in porous media with biofilms in equilibrium and non-equilibrium conditions

Transport of biologically reactive dissolved solutes in a saturated porous medium including a biofilm-phase occurs in various technological applications such as in biochemical or environmental engineering. It is a complex process involving a wide variety of scales (from the bacteria-scale to the aquifer-heterogeneities-scale in the case of groundwater remediation) and processes (hydrodynamic, physicochemical and biochemical). This work is devoted to the upscaling of the pore-scale description of such processes. Firstly, one-equation macroscopic models for bio-reactive transport at the Darcy-scale have been developed by using the volume averaging method; they will be presented below. These one-equation models are valid for different limit cases of transport; their validity domains in terms of hydrodynamic and biochemical conditions will also be discussed. Finally, in order to illustrate such a theoretical development, an example of application to the operation of a packed bed reactor will be studied.

RichardsFoam2: A new version of RichardsFoam devoted to the modelling of the vadose zone

RichardsFoam2 is an updated version of the OpenFOAM® solver RichardsFoam, presented in Orgogozo et al., Comput. Phys. Commun. 2014. The new features are the following: (i) The direct handling of fully heterogeneous porous media, with all the van Genuchten parameters defined as spatially varying scalar fields. (ii) The computation of the density of water flux at each face of the mesh cells, which allows the implementation of fixed water flux (e.g.: rain flux) boundary conditions. (iii) The integration in the water flow resolution of the actual evapotranspiration within the root zone, computed on the basis of the potential evapotranspiration. These new features allow to deal with the hydrology of real (i.e.: heterogeneous) soils in natural conditions, submitted to rain and evapotranspiration. Thus it considerably broadens the field of applicability of the OpenFOAM® solver for Richards equation. The description of the elements contained in this release may be found in the readMe file. In RichardsFoam2_presentation.pdf, one will find a more detailed description of the new features offered by RichardsFoam2 (equations, descriptions of the proposed test cases,…,…).