Procédés et mécanique aux petites échelles PROMETHEE
Micro-objets biomimétiques & encapsulation
Modélisation des surfaces et des interfaces
L'équipe PROMETHEE (Procédés et mécanique aux petites échelles) s'intéresse à des thématiques scientifiques aussi variées que pointues:
étude microfluidique de fluides complexes et bio-fluides,
procédés et systèmes micro-structurés,
modélisation mathématique, physique et numérique des interfaces et des interactions fluide-structure.
La complexité introduite par ces phénomènes nécessite le développement de méthodologies originales développées dans le groupe. Ces développements méthodologiques concernent les forces intermoléculaires et interfaciales, la thérmodinamique des systèmes complexes , les procédés d'émulsification et de micro-encapsulation ainsi que les méthodes des éléments finis de frontière.
Le groupe composé de 5 permanents se structure autour de plusieurs axes de recherche principaux:
Xue Chen, Paul G. Chen, Jalil Ouazzani, Qiusheng Liu. Numerical simulations of sessile droplet evaporating on heated substrate. European Physical Journal - Special Topics, EDP Sciences, 2017, 226 (6), pp.1325-1335. Plus de détails...
Motivated by the space project EFILE, a 2D axisymmetric numerical model in the framework of ALE method is developed to investigate the coupled physical mechanism during the evaporation of a pinned drop that partially wets on a heated substrate. The model accounts for mass transport in surrounding air, Marangoni convection inside the drop and heat conduction in the substrate as well as moving interface. Numerical results predict simple scaling laws for the evaporation rate which scales linearly with drop radius but follows a power-law with substrate temperature. It is highlighted that thermal effect of the substrate has a great impact on the temperature profile at the drop surface, which leads to a multicellular thermocapillary flow pattern. In particular, the structure of the multicellular flow behavior induced within a heated drop is mainly controlled by a geometric parameter (aspect ratio). A relationship between the number of thermal cells and the aspect ratio is proposed。
Xue Chen, Paul G. Chen, Jalil Ouazzani, Qiusheng Liu. Numerical simulations of sessile droplet evaporating on heated substrate. European Physical Journal - Special Topics, EDP Sciences, 2017, 226 (6), pp.1325-1335. <10.1140/epjst/e2016-60203-y>. <hal-01509843>
Journal: European Physical Journal - Special Topics
B. Bernales, Pierre Haldenwang, Pierrette Guichardon, Nelson Ibaseta. Prandtl model for concentration polarization and osmotic counter-effects in a 2-D membrane channel. Desalination, Elsevier, 2017, 404, pp.341 - 359. Plus de détails...
B. Bernales, Pierre Haldenwang, Pierrette Guichardon, Nelson Ibaseta. Prandtl model for concentration polarization and osmotic counter-effects in a 2-D membrane channel. Desalination, Elsevier, 2017, 404, pp.341 - 359. <10.1016/j.desal.2016.09.026>. <hal-01405589>
E Alekseenko, B Roux, D Fougere, Paul G. Chen. The effect of wind induced bottom shear stress and salinity on Zostera noltii replanting in a Mediterranean coastal lagoon. Estuarine, Coastal and Shelf Science, Elsevier, 2017, 187, pp.293-305. Plus de détails...
The paper concerns the wind influence on bottom shear stress and salinity levels in a Mediterranean semi-enclosed coastal lagoon (Etang de Berre), with respect to a replanting program of Zostera noltii . The MARS3D numerical model is used to analyze the 3D current, salinity and temperature distribution induced by three meteorological, oceanic and anthropogenic forcings in this lagoon. The numerical model has been carefully validated by comparison with daily observations of the vertical salinity and temperature profiles at three mooring stations, for one year. Then, two modelling scenarios are considered. The first scenario (scen.## 1), starting with an homogeneous salinity of S = 20 PSU and without wind forcing, studies a stratification process under the influence of a periodic seawater inflow and a strong freshwater inflow from an hydropower plant (250 m3/s). Then, in the second scenario (scen.## 2), we study how a strong wind of 80 km/h can mix the haline stratification obtained at the end of scen.## 1. The most interesting results concern four nearshore replanting areas; two are situated on the eastern side of EB and two on the western side. The results of scen.## 2 show that all these areas are subject to a downwind coastal jet. Concerning bottom salinity, the destratification process is very beneficial; it always remains greater than 12 PSU for a N-NW wind of 80 km/h and an hydropower runoff of 250 m3/s. Special attention is devoted to the bottom shear stress (BSS) for different values of the bottom roughness parameter (for gravels, sands and silts), and to the bottom salinity. Concerning BSS, it presents a maximum near the shoreline and decreases along transects perpendicular to the shoreline. There exists a zone, parallel to the shoreline, where BSS presents a minimum (close to zero). When comparing the BSS value at the four replanting areas with the critical value, BSScr, at which the sediment mobility would occur, we see that for the smaller roughness values (ranging from z0 = 3.5 × 10-4 mm, to 3.5 × 10-2 mm) BSS largely surpasses this critical value. For a N-NW wind speed of 40 km/h (which is blowing for around 100 days per year), BSS still largely surpasses BSScr - at least for the silt sediments (ranging from z0 = 3.5 × 10-4 mm, to 3.5 × 10-3 mm). This confirms the possibility that the coastal jet could generate sediment mobility which could have a negative impact for SAV replanting.
E Alekseenko, B Roux, D Fougere, Paul G. Chen. The effect of wind induced bottom shear stress and salinity on Zostera noltii replanting in a Mediterranean coastal lagoon. Estuarine, Coastal and Shelf Science, Elsevier, 2017, 187, pp.293-305. <10.1016/j.ecss.2017.01.010>. <hal-01453377>
Camille Maumet, Tibor Auer, Alexander Bowring, Gang Chen, Samir Das, et al.. Sharing brain mapping statistical results with the neuroimaging data model. Scientific Data , Nature Publishing Group, 2016, 3, . Plus de détails...
Only a tiny fraction of the data and metadata produced by an fMRI study is finally conveyed to the community. This lack of transparency not only hinders the reproducibility of neuroimaging results but also impairs future meta-analyses. In this work we introduce NIDM-Results, a format specification providing a machine-readable description of neuroimaging statistical results along with key image data summarising the experiment. NIDM-Results provides a unified representation of mass univariate analyses including a level of detail consistent with available best practices. This standardized representation allows authors to relay methods and results in a platform-independent regularized format that is not tied to a particular neuroimaging software package. Tools are available to export NIDM-Result graphs and associated files from the widely used SPM and FSL software packages, and the NeuroVault repository can import NIDM-Results archives. The specification is publically available at: http://nidm.nidash.org/specs/nidm-results.html.
Camille Maumet, Tibor Auer, Alexander Bowring, Gang Chen, Samir Das, et al.. Sharing brain mapping statistical results with the neuroimaging data model. Scientific Data , Nature Publishing Group, 2016, 3, <10.1038/sdata.2016.102>. <inserm-01411025>
The equations of fluid motions are considered in the case of internal energy depending on mass density, volume entropy and their spatial derivatives. The model corresponds to domains with large density gradients in which the temperature is not necessarily uniform. The new general representation is written in symmetric form with respect to the mass and entropy densities. For conservative motions of perfect thermocapillary fluids, Kelvin's circulation theorems are always valid. Dissipative cases are also considered; we obtain the balance of energy and we prove that equations are compatible with the second law of thermodynamics. The internal energy form allows to obtain a Legendre transformation inducing a quasi-linear system of conservation laws which can be written in a divergence form and the stability near equilibrium positions can be deduced. The result extends classical hyperbolicity theory for governing equations' systems in hydrodynamics, but symmetric matrices are replaced by Hermitian matrices. (C) 2016 Elsevier Ltd. All rights reserved.
Henri Gouin. Properties of thermocapillary fluids and symmetrization of motion equations. International Journal of Non-Linear Mechanics, Elsevier, 2016, 85, pp.152-160. <10.1016/j.ijnonlinmec.2016.06.003>. <hal-01461793>
Journal: International Journal of Non-Linear Mechanics