Our Computational Physics group carries out research into numerical methods for solving hydrodynamics problems, coupled to particle transport phenomena, with the aim of developing state-of-the-art nuclear weapon simulation codes.
Breadth of Work
Currently our work is expanding as the role of computer simulation increases from model interpolation to a predictive capability. The emphasis is on improving the underlying numerical techniques, reducing the approximations made in the physics equations being solved, extending the equations to three dimensions, and utilising the new parallel computing technologies. In addition, the roles of Verification & Validation are gaining importance as simulations become increasingly complex. The codes are also capable of wider application.
Hydrodynamics
In hydrodynamics the key challeneges are increasing the accuracy and stability of the numerical methods as the calculations use greater resolution both in one, two and thee dimensions. Significant code developments are underway both in 2D and 3D, utilising Massive Parallel Processing (MPP), employing mesh domain decomposion, and using the Arbitrary Lagrange Eulerian (ALE) technique and the Adaptive Mesh Refinement technique (AMR).
Particle Transport
AWE is investigating the use of the Monte Carlo technique, as well as deterministic solvers of the Boltzmann equation, which generally relate to radiation and neutronics phenomena. The Monte Carlo technique lends itself naturally to parallel solvers, but effort is constantly required to balance the needs of affordability and statistical noise. The deterministic techniques require an implicit solver which demands the iterative solution of a large set of coupled equations; a major challenge on parallel supercomputers.
Verification & Validation
Verification & Validation are increasingly important and significant innovation is required to gain confidence in a complex physics simulation. Individual models are verified against analytic solutions where possible, before testing against established simulations and experimental data.
Nuclear Effects
The Nuclear Effects Group is interested in the hostile and disturbed environments created by high-altitude nuclear bursts, and their effects on the performance of systems.