Ongoing research projects

IMMC

Ongoing research projects in iMMC (February 2020)


This a short description of research projects which are presently under progress in iMMC.
Hereunder, you may select one research direction or choose to apply another filter:

Biomedical engineering

Computational science

Civil and environmental engineering

Dynamical and electromechanical systems

Energy

Fluid mechanics

Processing and characterisation of materials

Chemical engineering

Solid mechanics


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List of projects related to: Fluid mechanics




Numerical modelling of estuaries and coastal seas
Researcher: Valentin Vallaeys
Supervisor(s): Eric Deleersnijder

The topic of the research is the numerical modelling of the river-to-sea continuum of major rivers (i.e. Congo River and Columbia River). The goal is to study the estuarine and coastal dynamics and their interactions with tides, river discharges and atmospheric/oceanic circulations. This thesis partly answers the following questions: What is the dynamics of the river-to-sea continuum ? How does the small scale influence the larger one (and vice-versa) ? Can Discontinuous Galerkin methods reduce the numerical dissipation in order to simulate sharp fronts of density and velocity fields ? This thesis is performed within the framework of the SLIM project (http://sites.uclouvain.be/slim/).



Impacts of energy efficiency and energy availability on economic growth
Researcher: Elise Dupont
Supervisor(s): Hervé Jeanmart

I am working on the link between energy availability and accessibility and economic growth. To do so, I study the concept of Energy Return on Investment (EROI), which is the ratio of the energy that is produced by an energy conversion device throughout its lifetime to all the energy inputs that were invested from the extraction of raw materials to the end-of-life treatment of the facility. It is the best indicator to assess the quality and sustainability of an energy project, without any economic distorsion. Easy access to high EROI resources allowed our modern societies to develop their economic activities. However, even taking into account the technological progress, the amount of high EROI resources is decreasing because : (i) EROI of fossil fuels is declining over time, (ii) renewable alternatives have lower EROIs than traditional fossil fuels and (iii) EROI of renewable alternatives is declining with their spatial expansion.

I am developing a methodology to estimate the dynamic function for the evolution of the EROI of different renewable energy sources (wind, solar and biomass) with the cumulated annual production, in order to be able to accurately estimate the evolution of the EROI of the future energy system.



Implementation of an incompressible hybrid Eulerian-Lagrangian external flow solver
Researcher: Philippe Billuart
Supervisor(s): Grégoire Winckelmans, Philippe Chatelain

Philippe Billuart is working on the development of a new numerical solver that will be able to solve accurately and efficiently any low Mach number external flows. His research is focusing on the hybrid Eulerian-Lagrangian solvers for the incompressible Navier-Stokes equations. Those approaches are based on the decomposition of the computational domain : an Eulerian grid-based solver is used for the computation of the near-wall region, while a Lagrangian vortex method solves the wake region. Even though the coupling of particle methods with Eulerian solvers is not new, only 3D weak coupling were developed so far. This thesis aims to develop a 3D strong coupling ; i.e. a coupling where the Schwarz iterations are not longer required to ensure consistent boundary conditions on each subdomain. As the Schwarz algorithm becomes expensive in 3D, the computational gain in the developed approach should be very significant.



Comprehensive Wake Simulation for the Analysis of Vortex Interactions with Flexible Devices: Application to Rotorcraft and Formation Flying Aircraft
Researcher: Denis-Gabriel Caprace
Supervisor(s): Grégoire Winckelmans

This research is about developing tools for wake flow analysis, and their application to rotorcraft and aircraft in formation flight.



COMPACTSWIM : compliant actuation and embodied intelligence in biomimetic propulsion for swimming : principles, simulation, and design.
Researcher: Caroline Bernier
Supervisor(s): Philippe Chatelain, Renaud Ronsse

This project is in between Robotics and Fluid Mechanics and aims at the design of robust and efficient biomimetic swimming agents. The approach used to tackle the problem distinguishes itself from a broad body of work by a unique combination of multi-disciplinary tools: (i) high-fidelity Computational Fluid Dynamics to simulate self-propelled swimmers; (ii) compliant actuators to generate energy-efficient force-controlled patterns; (iii) oscillator-based coordination to distribute the computational load within a biologically inspired controller; and (iv) advanced optimization algorithm to calibrate the control schemes for a large variety of gaits. Different and complementary swimming gaits will be investigated, like energy-efficient or fast. Using compliant actuators will allow the swimmer to sense the fluid reactions being useful for its propulsion and exploit energy storage in the elastic deformations of the actuator.



Automatic hexahedral mesh generation for boundary layers
Researcher: Christos Georgiadis
Supervisor(s): Jean-François Remacle

The main objective of our work is to provide with a fast and reliable method for generating boundary layer meshes. We follow a strategy that uses direction fields and a frontal point insertion strategy. The input of our algorithm is an initial triangular mesh of our domain and a direction field calculated on it. The goal is to compute the vertices of the final mesh by an advancing front strategy along the direction field. The final mesh will consists of right angle triangles, optimal for merging into quadrilaterals.



Tidal response of Titan liquid bodies
Researcher: David Vincent
Supervisor(s): Eric Deleersnijder

Titan, a moon of Saturn, has various liquid bodies: surface lakes and seas filled with liquid hydrocarbons and a global subsurface ocean of water.
I numerically studied the tidal flow (see Fig. 1, the tidal ellipses of the first tidal component in Kraken and Ligeia Maria) and motion of the surface lakes and seas by means of SLIM (www.climate.be/slim). The harmonics of the tidal motion (for instance, the tidal range and phase in Kraken and Ligeia Maria, see Fig. 2) and eigenmodes were also studied in order to assess the likelihood of resonance (local or global). Values predicted by the model such as the tidal range and flow of the surface lakes and seas are useful for designing some aspects of the future observation missions.
I am currently modeling the tidal response of Titan's global subsurface ocean by taking into account the solid-fluid interactions with Titan icy crust (see Fig. 3, the sea surface elevation of Titan's ocean with a free top boundary). The dissipation and resonance phenomena will then be studied. The originality of this work lies in the fact that the dynamic tides are taken into account.



Techno-economic viability of variable-speed pumped-storage hydropower based on centrifugal pumps used as turbines
Researcher: Thomas Mercier
Supervisor(s): Emmanuel De Jaeger

This research takes place in the frame of SmartWater, a 3.5-year research project funded by the Walloon region, Belgium, and whose goal is to investigate the conversion of former mines and quarries into pumped-storage hydropower (PSH) sites, taking advantage of existing cavities. The project involves several academic and industrial partners, among which Laborelec, Electrabel and Cofely, as well as sponsors, including Ores, Elia, Charmeuse and Ensival-Moret. The SmartWater project is divided in several work packages, ranging from the geological study of potential mines and quarries, to the economical and electromechanical aspects of pumped-storage hydropower.



Modelisation and optimization of bird flight
Researcher: Victor Colognesi
Supervisor(s): Philippe Chatelain, Renaud Ronsse

This research project aims at modeling and optimizing bird flight. The goal of this modelization is to get a deep understanding of the mechanisms that govern avian flight and the best way to understand it is to re-create it. That is, the flight will be modeled starting from the given anatomy of a bird and the kinematics will be the result of an optimization process aiming at the most optimal flight.
Compared to other existing studies on the subject of bird flight, this project will follow a "bottom-up" approach, all the way from muscle activation, up to the wing aerodynamics and gait optimization. This approach is necessary to be able to evaluate key values such as metabolic rates, ...
This will allow us to answer a few questions such as :
- What are the mechanisms enabling high efficiency in bird flight ?
- How do we achieve a stable flapping flight ?
This work is purely numerical. The bio-mechanical model of the bird is developed using the multi-body solver Robotran developed at UCL. This bio-mechanical model will be coupled to an aerodynamical model based on a vortex particle-mesh code (VPM) developed at UCL as well.



DNS of reacting particle flows for mesoscale modeling
Researcher: Baptiste Hardy
Supervisor(s): Juray De Wilde, Grégoire Winckelmans

Gas-solid flows are encountered in many natural and industrial phenomena. Fluidized beds are the most well known application of gas-solid reactors in the chemical industry (catalytic cracking, biomass conversion,...).
However, the simulation of such equipments at large scale is still an issue due to the tracking of billions of particles carrying the reaction while interacting with the gas flow. Eulerian-Eulerian models are currently very popular because they describe the solid phase as a continuum, hence drastically lowering the computational cost. Though, these models require closure relations for momentum, heat and mass transfer, often obtained on empirical bases.
The goal of this research is to extract closure laws from Direct Numerical Simulations at particle scale using the Immersed Boundary Method in order to provide new mesoscale models built on physical grounds.



RevealFlight
Researcher: Gennaro Vitucci
Supervisor(s): Renaud Ronsse

Currently under investigation is a reductionist model of flight of birds. Main focuses are a neuromuscular control system and fluid-solid interaction at wing level both for a single agent and large flocks.



Flight Control and Wake Characterization of Migratory Birds
Researcher: Gianmarco Ducci
Supervisor(s): Renaud Ronsse, Philippe Chatelain

The RevealFlight project aims at shedding light on the efficiency optimization mechanisms deployed by biological flyers, with a specific focus on migratory birds. The efficiency-seeking mechanisms will be sought through the numerical reproduction of flight that includes the morphology, the neuro-muscular configuration and the gait generation. This resulting gait then exploits aerodynamics at the scale of an individual (unsteady lift generation) and at the level of the flock (formation flight). This project thus proposes to synthesize the flight mechanics of birds into a unified framework, combining bio-mechanical, sensory, aerodynamic and social interaction models, in order to reproduce the flying gaits and the interactions within a flock.
A neuro-mechanical model of the birds is currently under development, capturing bio-inspired principles both in the wing bio-mechanics (e.g. structure and compliance) and in its coordinated control (through e.g. a network of coordinated oscillators). The dynamics of this model will be solved by means a multi-body solver and in turn, coupled to a massively parallel flow solver (an implementation of the Vortex Particle-Mesh method) in order to capture the bird’s wake up to the scales of the flock. The study of self-organization phenomena and inter-bird interactions are currently beginning on simple conceptual models, and will be gradually extended to more advanced models developed during the project. It will aim at comparing the efficiency of flocks of selfish flyers with that of flocks in which collaboration takes place, whether implicitly or explicitly.
In my global project picture, the following bottom-up strategy will be adopted:
- Wake characterization: This task studies the wake in terms of the vortex dynamics at play over long distances. The candidate will perform simulations of flying agents in long computational domains in order to capture the wake behavior (topology, instabilities and decay) over longer times and larger scales. This will provide another basis of validation of the project results, given the volume of work on bird wakes;
- Flight stabilization in turbulent or wake-impacted flow: This task aims at the realization of a stabilized flight within a perturbed flow. Two perturbations are envisioned: ambient turbulence and an analytical wake composed of two counter-rotating vortices. Il will Combine previously synthesized gaits and control schemes in order to study the stability of the flyer in a turbulent flow or inside a wake;
- Maneuvers: This task realizes the first maneuvers of the virtual flyer: avoidance and trajectory tracking that will be leveraged in the simulation of multiple flyers that need to interact and swap places. In the present task, this trajectory is still prescribed, in a step towards an autonomous decision-making agent. In order to realize maneuvers, this task implements a control layer above the controllers developed in earlier tasks. Complex maneuvers will be achieved by closing the loop between trajectory errors and the inputs of the lower level controller.



Development of high-fidelity numerical methods for the simulation of the aerothermal ablation of space debris during atmospheric entry
Researcher: David Henneaux
Supervisor(s): Philippe Chatelain

This project, lead in collabaration with the von Karman Institute (VKI) and Cenaero, aims at developing high-fidelity numerical methods for the simulation of the aerothermal ablation of space debris during an atmospheric entry.
The number of space debris orbiting the Earth is becoming increasingly problematic for the integrity of operational satellites and the future access to space. The many space debris mitigation projects currently under study require an accurate prediction of the degradation of these objects when they re-enter the atmosphere in order to comply with the severe re-entry safety requirements.
Dedicated engineering softwares are used to assess the survivability of these debris. However, the correlation-based models implemented in these software lack accuracy and they do not allow to gain insight into the complex flow phenomena taking place near the surface of the body, yet essential for the conception of new satellites designed for demise. That is why CFD methods are needed to study this complex situation. But the methods currently available rely on simplifying assumptions that compromise the reliability of the results.
The objective of this project is to develop new high-fidelity numerical methods able to deal with the presence of the three phases in the same domain and their complex interactions. They will be grouped into the ARGO code under development at CENAERO, VKI, and UCL, which relies on the discontinuous Galerkin method. To do so, a highly-accurate multiphase method coupled with evaporation and surface tension models and based on a sharp interface approach will be employed for the treatment of the gas-liquid interface, while a state of the art melting method accounting for the diffuse character of the liquid-solid interface will be considered. Both methods will be built to work with multicomponent compressible equations. The code will then be validated with experimental data from the VKI Plasmatron facility.



Improvement of gas quality in small-scale biomass gasification facilities through steam injection
Researcher: Arnaud Rouanet
Supervisor(s): Hervé Jeanmart

Biomass, as a renewable fuel, can be converted in a gasifier to produce a synthetic gas that is easier to transport and has a wider range of applications than solid biomass, including bio-fuels, chemicals or energy production.
In order to improve the quality of the produced gases, we will investigate how steam can be used instead of air as the oxidizing agent, to limit the syngas dilution with inert nitrogen and increase its heating value. The project will focus on improving an existing small-scale two-stage gasification unit owned by UCL, on which ad-hoc modifications will be brought and experimental campaigns will be performed.
Theoretical calculations and literature reviews will be performed to confirm and precise the potential for improvement of syngas composition. The design and ideal location of steam injection points will be studied, and experiments will be conducted on the modified gasifier to complement the theoretical calculations. Advanced tools and methods will be used for the characterisation of the syngas composition, to increase the accuracy of the experimental results. Finally, a numerical model of the gasification process will possibly come as complement for a more accurate prediction and confirmation of the experimental results.
This research project will take place in the frame of the project ENERBIO, in collaboration with ULB, UMons and CRA-W.