Many engineering applications foreseen the usage of small particles for groundwater remediation or for sealing damaged geological confinement barriers, however, delivering materials to a contaminated or damaged region is challenging. TRACE-it aims at controlling the flow of colloidal particles in subsurface geological environments using in situ solute concentration gradients. The phenomenon, known as diffusiophoresis, has a tremendous potential to move colloids to regions that are inaccessible by conventional transport. Diffusiophoretic transport in porous media, however, has received very little attention so far, especially in standard transport in porous media models where it remains unconsidered. What is the magnitude and location of solute concentration gradients produced during subsurface processes? How to use these gradients to transport colloids towards target regions? The answers will be found through a combined experimental-modelling approach to: (i) measure coupled hydro-electro-chemical dynamics, (ii) characterize concentration gradients generated in situ in geological porous media, (iii) identify the influence of concentration gradients on particle transport and develop a macroscale model of transport in porous media that includes diffusiophoresis. TRACE-it integrates the usage of microfluidic experiments, observation techniques, and multi-scale computational fluid dynamics to describe the transport mechanisms at the pore-scale before upscaling to the continuum-scale. The experimental-modelling toolset will open new ways for moving colloidal particles by sensing chemical gradients generated naturally or from human activity, leading them to their target such as oil, contaminants, or reacting minerals. During column-scale experiments, controlling colloid transport will be achieved through the characterization of solute concentration gradients and the use of specifically designed particles.
Partners: University of Orléans, University of Vienna
The search for biologically driven alterations on Mars and its potential as habitat for past or present life is a primary aim of the upcoming Mars exploration missions. While a range of environments that would have been well suited to support a potential chemolithotrophy on Mars have been proposed, our understanding of putative biosignatures to be targeted in Martian materials is still poor. A valuable source of information can be extracted from microbial fingerprints of chemolithotrophic life based on Martian materials (Martian meteorites, regolith simulants). Chemolithotrophic microorganisms employ an astonishing number of metabolic pathways to extract energy from diverse inorganic electron donors/acceptors, shaping global biogeochemical cycles. Using a holistic approach based on laboratory, field and space exposure experiments, we propose to investigate interactions of Earth’s various chemolithoautotrophs with Martian materials. The bottom-up exploration of mineral-microbial interactions for different chemolithotrophs cultivated on Martian materials as the sole energy sources, will decipher mineral and metabolic biosignatures associated with these cases. This project explores unique microbial interactions with extraterrestrial materials down to the nanoscale and atomic resolution utilizing a comprehensive toolbox of cutting-edge techniques. BioMaMa will identify preservable biomarkers/biosignatures of chemolithotrophic life on Martian materials after the exposure to simulated Martian conditions at low Earth orbit and ground-based facilities. A complex approach will be used to investigate meteorite-microbial interactions in Mars-analogue sites on Earth. The extensive knowledge gained from BioMaMa will help to understand and critically interpret the results of future Mars exploration missions (ExoMars 2020). These studies will lay the foundation for efficient nanoanalytical spectroscopy of returned Mars samples, to critically assess their potential biogenicity.
This project will combine wind tunnel experiments with numerical simulations and a sensitivity analysis to improve the control authority of pulsed jet actuators (PJAs) to separated turbulent flows over a 2.5D airfoil equipped with a flap. The target of this approach is to determine the minimum net-mass-flux required by pulsed jet actuators to compensate for the momentum deficit in the boundary layer. Controlling separation contributes to a decrease in the energy demand, leading to a decrease in CO2 emissions. It also improves the maneuvering capability, safety, and durability of the aircraft by reattaching the boundary layer and suppressing instabilities. The present work considers the sensitivity analysis, using a hierarchy of numerical models, using Reynolds-averaged Navier-Stokes simulations and large eddy simulations for both the flow inner and outer flow. These simulations will be calibrated using wind tunnel experiments by means of a data-assimilation method. The sensitivity analysis will then allow for determining the optimal parameters of the pulsed jet actuators such as operating frequency, output velocity together with their geometry including the actuators’ outflow aspect ratio, chordwise position and inter-actuator distance in the spanwise direction. The selected technology of PJAs will be an improved design of energy efficient fluidic oscillators capable of reaching high outflow velocities with operating frequencies ranging in the natural unstable frequencies of the outer flow. Novel manufacturing techniques such as xurography will also be tested to improve the cost and fabrication time of the PJAs, as well as their integration on the wing. Furthermore, the project will investigate the manufacturing and flow-control capabilities of dual-frequency fluidic oscillators, which may allow for further decreasing the net-mass-flux of the actuators by triggering instabilities with greater potential in altering boundary-layer separation.