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The 23 June 2022 at 15h30

PhD Defense : Thomas LAFARGE :” Lattice Boltzmann method for multiphase flows”

Nathalie BROUSSET |  Conference room, CERFACS, Toulouse, France |  


You tube link : https://youtu.be/E9aSeMW1QgM

Abstract :

This PhD study intends to evaluate Lattice Boltzmann Methods (LBM) applied to multiphase flows. First, a general review of statistical physics for Lattice Boltzmann Methods is conducted, as well as a particular review of LBM methods for two-phase flows. General principals are presented, and the Color Gradient, Pseudo-Potential, Free Energy and HCZ, are successively presented. Lattice Boltzmann Methods advanced notions are then introduced, in particular, a Taylor expansion allowing to determine Lattice Boltzmann schemes equivalent macroscopic equation is described.

A Color Gradient method theoretical study is then proposed. First, an original reformulation of the algorithm allowing to improve the computational efficiency is proposed. The Taylor expansion method then allows to determine the high order errors induced by the numerical scheme. This underlines the relationships between the degree of isotropy of LBM operators and the numerical scheme stability. In particular, a numerical isotropic operator allowing to introduce an equation of state is proposed. This operator efficiency is illustrated on academical test cases. The Taylor expansion method is also applied to demonstrate that the Color Gradient Method allows to solve an Allen-Cahn phase field equation. This Allen-Cahn equation allows a perfect control of the diffuse interface thickness. This theoretical result is then validated numerically. Finally, an original improved version of the Gradient Color Method is proposed. In this formulation, our isotropic Equation of State operator is used, and an original temporal correction term is proposed. This temporal correction improves the scheme numerical stability and allows to expands the method application range to higher density ratios. Finally, this method is validated through academical testcases.


François Dubois, Laboratoire de mathématiques d'Orsay – Referee

Florian de Vuyst, Université de Technologie de Compiègne – Referee

Umberto d'Ortona, M2P2 –  Member

Rémi Abgrall, University of Zurich –  Member

Bénédicte Cuenot, CERFACS – Director

Pierre Boivin, M2P2 –  co-director

Nicolas Odier, CERFACS –  co-advisor

Stefano Puggeli, SafranTech – co-advisor


Catherine Lambert awarded Officer in the national order of Merit

Brigitte Yzel |  31 May 2022

Catherine LAMBERT, President of Cerfacs, has been promoted to the grade of officer in the national order of Merit, on the proposal of Mrs. Frédérique Vidal, Minister of Higher Education, Research and Innovation. Antoine PETIT, President and CEO of the CNRS, presented the insignia to Catherine LAMBERT during a ceremony that brought together many actors from the space, aeronautics, environment and digital sectors. Antoine PETIT: "Catherine's interpersonal skills, her ability to step back and understand very different environments (research, industry, politics) in order to develop a collective vision are the hallmarks of her career. Catherine is one of those people with whom you naturally feel confident, with whom you want to build something that goes beyond all of us to go further. With this honor, the Cerfacs teams are also rewarded.Read more

Sparse Days in Saint-Girons IV

Brigitte Yzel |  29 March 2022

Sparse Days Meeting 2022 🗓️  20-22 June 2022  @ Saint-Girons, France   🌐   Sparse Days 2022 will be held in Saint-Girons, Ariège, from 20-22 June. This enhanced version of Sparse Days is being co-organized by Cerfacs and ENSEEIHT/IRIT. It will be the fourth meeting in Saint- Girons following the tradition of the previous meetings held in 1994, 2003, and 2015. The tradition involves coupling our highly successful annual technical meeting with the ambience and hospitality of this wonderful Pyrenean town which encourages fruitful informal exchanges between participants.    Read more