Advanced Lattice-Boltzmann Understandings for Multiphysics Simulations – ALBUMS

The work is based on an innovative method, the Boltzmann network method. This method, based on a mesoscopic approach, consists in predicting the spatio-temporal evolution of the probability density functions associated with the particles that make up the fluid. An original method, known as hybrid recursive regularization method, is at the heart of the work. This method, developed in the M2P2 laboratory, has very interesting properties of accuracy, stability and computational cost. Within the framework of the Chair, it is extended to turbulent compressible flows in the presence of moving solid bodies.

Results to date include

- the extension of the method for supersonic flows
- improvement of the algorithm for taking into account moving solid objects
- improved solid wall modeling in the presence of turbulent boundary layers
- the development of hybrid RANS/LES turbulence models optimized for Lattice Boltzmann's methods

Prospects after 18 months include the consolidation of theoretical developments, then deployment and validation on industrial cases.

After 18 months, several articles have appeared or are currently being reviewed in leading international peer-reviewed journals.

The Chair project deals with the development of efficient Latice-Boltzmann Methods (LBM) for the simulation of flows in realistic industrial applications in the field of aerodynamics, aeroacoustics and heat transfer, e.g. installed aircraft engine, car engine under hood, full car/aircraft with moving elements. This Chair is supported by three leading companies, namely Airbus, Renault and Safran. The Chaire candidate is Prof. Pierre Sagaut from M2P2 Laboratory (Aix-Marseille Université/CNRS/Ecole Centrale Marseille). The research program is organized in four axes, each one aiming at removing a scientific lock of major importance for the use of LBM for applications. These methods have become essential in the field of Computational Fluid Dynamics because of their very high efficiency compared to classical tools based on the resolution of Navier-Stokes equations, in particular for low-Mach massively separated flows. Their extension to highly compressible flows and the possibility of treating increasingly complex cases in terms of geometry (including deformable solid objects and/or with arbitrary kinematics) is therefore a crucial issue in terms of deployment strategy of these methods for engineering and raises many theoretical questions on numerical methods and physical models. The four research themes that structure the Chair are:

- numerical modelling of solid walls, including heat transfers
- the development of efficient LBM methods for the simulation of highly compressible flows and shock capturing
- development of LBM methods for flow simulation in the presence of deformable solids and/or in arbitrary motion
- modelling turbulence within the framework of LBM methods, taking into account their specificities (nested uniform Cartesian meshes, discretization errors, etc.)

The governance of the project is organised on three levels:
- a Technical Committee, which ensures the operational follow-up on a monthly basis of all the tasks defined within the themes. This committee is composed of the chairholder, the heads of each research theme, and a representative of each industrial partner.
- the Steering Committee, which meets twice a year and discusses and approves the main orientations and monitors the Chair's budget.
- an International Advisory committee, composed of leading French and foreign researchers on the project's research themes, which will meet at least three times over the four years of the project. Its role will be to assist the steering committee in making decisions by providing an analysis of the international context and a prospective vision of LBM methods, and also by recommending international collaborations.

In addition to the work of the permanent researchers at M2P2, the resources implemented consist of 4 thesis funding (one on each theme) and 16 years of post-doctorate (spread over the four themes). Making research results available to a wide public is a strong focus of the project. In addition to the fact that all articles will be published in "Gold open access" format, the data and results will be published on a website dedicated to the Chair. This site will also contain an intranet to allow the exchange of non-public data between project members. This mechanism will be reinforced by the organization of two international workshops, to which the main international research groups involved in the four research themes will be invited. These events will be supplemented by doctoral training organized in conjunction with the Doctoral College at the Aix-Marseille site.