Development of a 3D ALE simulation code with polyhedral mesh reconnection and adaptation dedicated to compressible multi-material hydrodynamics. – ALE INC(ubator) 3D

1- Finding a postdoctoral was unsuccessfull
2- Several choices of frameworks are available freely on the web. Two or three seem adapted t our requirements, particularly CGAL and GMSH

GMSH seems the most appropriate one especially because the principal investigator of this project (Rao Garimella, Los Alamos National Laboratory) is willing to invest some time to develop specifics applications for us within GMSH. Moreover the desire to deploy his tools in Europe ensures his commitment to our project also.

Because recruiting a postdoctoral with the right qualities seems difficult and risky we will adopt a different strategy. We think of recruiting a PhD student to deal with the research parts of the project (with a grant from other sources than ANR's ones). The implementation and heavy development will consequently be done by the consortium.

One article in International Journal of Numerical Methods in FLUIDS for the 3D Lagrangian scheme.

The goal of « ALE INC(ubator) 3D » project is to develop a 3D Arbitrary-Lagrangian-Eulerian code dedicated to multi-material hydrodynamics on general polyhedral mesh.

This project participates in a vast research initiative to produce energy using inertial fusion confinement initiated by lasers. The Laser-Mega-Joule project in Bordeaux, France, being one example of such initiative. The generated physical phenomena are fundamentally tri-dimensional and complex. Consequently the needs for numerical simulations are huge and a 3D ALE code environment would be a great help for the scientific community.

An ALE code is generally split into three phases
1.Lagrangian phase. A numerical scheme (Lagrangian on moving mesh) computes the spatio-temporal evolution of a mix of fluids in a Lagrangian formalism. As the mesh moves and deforms with the fluid, the mesh can be of arbitrarily bad geometrical quality (non convex, tangled, or skewed cells, etc.);
2.Mesh smoothing phase. Given a Lagrangian mesh the mesh smoothing consists in defining a better mesh to be used in the next time step;
3.Conservative remapping phase. The remapping phase consists in projecting the physical variables from the Lagrangian mesh onto the smoothed mesh. The remapping must be at least conservative and as accurate as the Lagrangian scheme.

The ALE INC(ubator) 3D code will possess the most recent Lagrangian numerical methods (centered and staggered) and mesh smoothing/reconnection/untangling techniques on polyhedral mesh. Moreover we will implement a technique allowing the number of cells to change during the simulation. This technique can be considered as a type of AMR (« Adaptive-Mesh-Refinement ») on polyhedral mesh. The last phase of the project will produce an extension of the code to handle multi-materials (mixed cells, interface reconstruction, remapping on pure meshes, etc.)
This environment will be implemented in parallel and we will adopt a validation and verification methodology for all phases of the project.
The up-to-date code will be distributed at each milestone, roughly speaking every year, in order to provide as soon as possible an efficient tool to potential users.