- Birth date and place: February, 7, 1961 in Enghien les Bains – France
- Nationality: French
- Current Position: Professor since 2000
- Institution: University of Strasbourg – France
I supervise continuously Ph-D works both in France and abroad. In the last 15 years, I supervised directly or in association with colleagues about 20 Ph-D theses.
My teaching tasks at the University are evenly distributed between academic courses and practical trainings. This activity mostly targets students enrolled in Master of Sciences and the two last years of Engineer Graduations. In the past, all my teaching stuff was devoted to mathematical methods for Geosciences (geostatistics, numerical analysis, optimization, inverse problems, signal processing) and Fluid Mechanics. Recently, I developed a complete course on Groundwater Hydrology for engineers including fundamentals and more advanced topics such as multi-phase flow, reactive transport, local scale reactivity, up-scaling techniques,…
I mostly work on the physics, the mathematical modeling and the inverse problems in relation with water and pollutant transfers within underground reservoirs. This work is developed along the following general topics:
(i) At scales from the lab experiment to that of natural reservoirs of small extend (say, 25 km2), I am working on the physics and the numerical techniques for solving transport in very heterogeneous media. My point is adding retention and nonlinear reaction processes between solutes, particles and the solid phase. I am also interested in the interpretation of hydraulic tests in wells by using inverse modeling. This work couples theoretical models (fractal, multi-fractal, multi-continuum representations of the medium) and the comparison with experimental data. We recently noted that occurrences of reciprocity gaps in hydrodynamic data might result in unanswered questions on the reliability of the so-called hydraulic tomography technique and also on underground flow inversion on the basis of hydraulic head data.
(ii) I am interested in Lagrangian approaches to flow and complex transfers in porous and fractured media. I mostly developed methods for the computation of advection – dispersion transport in the time domain. The calculation in the time domain allows reformulating exactly the sensitivities of concentrations to transport parameters such as fluid velocity, dispersion tensor, kinetic rate of sorption, etc.
(iii) With eventual applications to the above mentioned topics and to inverse problems, I am also interested in mathematical tools associated with sensitivity analysis of models to parameters. This also includes various techniques for inverting spatially distributed problem and data assimilation.
(iv) I am still working sporadically on stochastic partial differential equations even though they may suffer from limitations for homogenization in porous media. Therefore, I am leaning toward approaches inherited from statistical physics. The basic idea is to use equations from higher order than the classical advection-dispersion equation, for instance the Langevin equations or the random flights. The aim is to distribute the effects of heterogeneity on several terms instead of a single one (the dispersion) when homogenizing the local mechanisms of transport.
Delay, F, Badri, H, Fahs, M, Ackerer, P. 2017. A comparison of discrete versus continous adjoint states to invert groundwater flow in heterogeneous dual porosity systems. Adv. Water Resour. 110, 1-18.
Hasanne F, Delay F, Ackerer P. 2017. Estimating initial conditions for groundwater flow modeling using an adaptive inverse method. J. Hydrol., 552, 52-61. doi: 10.1016/j.jhydrol.2017.06.041.
Jerbi C, Fourno A, Noetinger B, Delay F. 2017. A new and fast method for estimating matrix block size in dual porosity model for large scale multiphase flow in fractured porous media. J. Hydrol., 548, 508-523, doi: 10.1016/j.jhydrol.2017.03.028.
Marinoni M, Delay F, Ackerer P, Riva M, Guadagnini A. 2016. Identification of groundwater flow parameters using reciprocal data from hydraulic interference tests. J. Hydrol., doi: 10.1016/j.jhydrol.2015.05.019.
Delay F, Ackerer P. 2016. The reduction of hydrological models for less tedious applications. CR. Geosc., 348, 89-98, doi: 10.1016/j.crte.2015.08.002.
Mara T, Fajraoui N, Younes A, Delay F. 2015. Inversion and uncertainty of highly parameterized models in a Bayesian framework by sampling the maximal conditional posterior distribution of parameters. Adv. Water Resour., 76.
Ackerer P, Trottier N, Delay F., 2014. Flow in double porosity aquifers: Parameter estimation using an adaptive multiscale approach. Adv. Water Resour. 73, 108-122.
Trottier N, Delay F, Bildstein O, Ackerer P. 2014. Inversion of a dual-continuum approach to flow in a karstified limestone: Insight into heterogeneity revealed by well-test interferences. J. Hydrol., 508, 157-169.
Fourno A, Grenier C, Benabdeerrahmane A, Delay, F. 2013. A continuum voxel approach to model flow in 3D fault networks : A new way to obtain up-scaled hydraulic conductivity tensors of grid cells. J. Hydrol., 493, 68-80.
Delay F, Porel G, Chatelier M. 2013. Modeling by a dual-flowing continuum results of denitrification in porous media colonized by biofilms. J. Contam. Hydrol., 150, 12-24; doi: 10.1016/j.jconhyd.2013.04.001
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