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PhD offer
Density current induced by collapse of sediments :
CT-Scan experiment and two-phase numerical simulation
Supervision / Laboratoire :
Damien Pham Van Bang (Prof.)
Laboratoire CT-Scan & Laboratoire Hydraulique Environnemental
Institut National de la Recherche Scientifique – Centre Eau Terre Environnement Parc technologique du Québec métropolitain, 2605 Blvd du Parc-Technologique
G1P 4S5 Québec (QC), CANADA damien.pham_van_bang@ete.inrs.ca


1. General problem and objectives
The collapse of granular material in water is ubiquitous in nature : granular avalanches (Fig. 1), landslides, river bank erosion, dam flushing…

Figure 1 : Effondrement d’une masse granulaire dans un fluide (A. Bougouin, 2017),
https://hal.archives-ouvertes.fr/hal-01924576/document)

During the sediment flow, the material creates a density current and generates motion to the ambient fluid. The flow properties of sediment and liquid and the resulting sediment bed are dependent on sediment (grain size, bulk density), fluid (viscosity, density) and bottom roughness. Pore pressure can also be generated within the sediment and could affect the system with fluidisation-liquefaction processes.
The PhD topic is focusing on two-phase numerical model on lock-exchange configuration. The experimental data by A. Bougoin (2017) will be first considered: but they will be completed with new experiment varying size-density of sediment, viscosity-density of water and bottom roughness. New experimental set up will include high-resolution measurement in time and space by an innovative combination of high speed particle image velocimetry (HS-PIV) and X-ray computed tomography (XRCT, https://ctscan.ete.inrs.ca/): fluid velocity and sediment velocity will be measured bay non-intrusive means. These two-phase measurements are obviously relevant to supply two-phase CFD code such as NSMP-3D which is co-developped with Conacyt-Cimat (Merida, Mexico, Dr. Miguel Uh Zapata) and Université Paris-Est-LHSV (Chatou, France, Prof. Kim Dan Nguyen).
2. Method and schedule
The PhD works will mainly consist in numerical simulation by using the NSMP-3D research code. During his first year, the PhD candidate will performed numerical test case in order to become familliar with the theory and the use of our code. For this appropriation step of the numerical tool and the scientific cluster (ComputeCanada, https://www.computecanada.ca/), the candidate will interact with Mexican and French partner through skype meetings and scientific visits. In parallel, the literature review on physical process involved during granular and density flows will be started with the objective to design a new experimental set-up. The development of experiment will start during the first year: technical staff of the Lab, BSc or MSc students will do set-up and preliminary experiment.
During second year, the candidate will perform experiments by the technical staff and NSMP-3D numerical simulations to reproduce them. He will submit communications and articles to conference and journals. Scientific visit will be organised with Mexican and/or French partners during the second year. During the third year, and depending on the achievement of this study, other configuration in relation to sediment transport would be explored by experimental and numerical modelling. The PhD defense is expected during the third year.

3. Required skills
 Fluid mechanics
 Applied mathematics (CFD)
 Computing language (Fortran, C++, Matlab)
 English is mandatory (French and/or Spanish is an advantage)

4. How to apply
This PhD topic is guarantee for 36 months. The study can start as soon as possible. To apply, the candidate should send : a/ letter of motivation (1p, english or french) b/ detailled CV c/ academic mark of the two last year
The potential candidate will be invited for Skype interview. Other documents like recommendation letters can be demanded during the selection process，