Modelization of wall conditions in ascendant gas-liquid flows inside fixed beds

Many chemical reactions are performed in fixed bed reactors with gas-liquid flows. Fixed bed reactors consist in a stack of solid porous particles of various shapes. With upflow, the bubbles pass in between the solid pellets and the liquid in the rest of the porosity  . At low velocities, the flow is governed by surface tension, gravity and viscous forces. Our team has developed Direct Numerical Simulation (DNS) models for single-phase flow in fixed beds and the PhD student is expected to extend this work to bubbly flows in catalytic fixed beds.
He/she will start by an investigation of the physics involved when a bubble in a liquid passes nearby a non-planar porous surface: film creation, thinning, collapse…? This part will be essentially bibliographical, but experiments at ISTO may be performed if necessary. One goal is to define at what spatial and temporal scales the mechanisms are taking place and to propose a model compatible with numerical simulation scales (~10 µm). The solids present a curvature at two spatial scales: ~1mm for the particle shape and ~1 µm for the porosity. The physical model and associated equations shall be validated to describe both these curvatures.
In a next step, the PhD student will focus on the implementation of the new models in OpenFOAM and the investigation of suitable numerical scheme, especially regarding the interface reconstruction step. Finally, he/she will use the model to simulate a lab scale fixed bed reactor. Simulations will be compared with available experimental data.
Join us if you want to push the limits of numerical simulations and help us improve green chemistry reactors  .

Keywords: Enthusiasm, curiosity, modelization, gas-liquid flow, wall law, OpenFOAM, Volume-of-Fluid, porous media,

• Academic supervisor    Dr. Cyprien Soulaine, Institut des Sciences de la Terre d’Orléans (ISTO)
• Doctoral School    EMSTU ED 552, https://collegedoctoral-cvl.fr/as/ed/page.pl?page=ed552 
• IFPEN supervisor    Dr. Lionel Gamet, Process and Experimentations division, Lionel.Gamet@ifpen.fr 
• PhD location    IFP Energies nouvelles, Lyon, France 
• Duration and start date    3 years, starting in fourth quarter 2022
• Employer    Nom, Ville, Pays
• Academic requirements    Master/Engineering degree in fluid mechanics, numerical methods
• Language requirements    Fluency in English and French 
• Other requirements    CFD, OpenFOAM, Programming in C++ / shell / Python, Chemical Eng.