A combined immersed body and adaptive mesh method for simulating neutron transport within complex structures

• Published in: Annals of nuclear energy 2019-12, Vol.134, p.88-100
• Main Authors: Buchan, A.G., Dargaville, S., Pain, C.C.
• Format: Article
• Language: English
• Subjects: Adaptive finite elements; Boltzmann transport equation; Immersed body method; Neutron transport
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/j.anucene.2019.05.044

•A new method combining immersed body projections and adaptive mesh resolution.•Provides solutions using optimized meshes specifically to resolve neutron transport.•Overcomes difficulties relating to large geometry conforming meshes.•Particularly beneficial for efficiently resolving complex domains and structures. This article describes a new adaptive immersed body method for the efficient and accurate modelling of neutron transport within geometrically complex domains. It combines two techniques of immersed body projections and self-adaptive mesh refinement to form a unique method that can efficiently resolve problems that contain complex internal structures. The approach allows complete freedom of where mesh resolution is placed and the meshes, which do not need to conform to the problem structure, are optimised for resolving the physics of the problem. Importantly the benefits can be found for problems with many internal structures such as fuel pins, control rods or cooling pipes and channels. Standard finite element meshes typically become large as they capture the geometrical detail and as a result solving times typically increase. This method overcomes this issue and allows for smaller meshes that are optimised to increase solution accuracy, as demonstrated in the numerical examples.