Core Concepts
A mortar thin shell approximation method is proposed to efficiently model the thermal behavior of superconducting accelerator magnets with thin insulation layers, enabling the use of non-conforming meshes across the interfaces.
Abstract
The paper presents a mortar thin shell approximation (mortar TSA) method for the thermal analysis of superconducting accelerator magnets. Superconducting magnets often contain thin volumetric layers, such as electrical insulation or turn-to-turn contacts, which can lead to unfavorable finite element (FE) meshes.
The proposed mortar TSA approach combines the concepts of thin shell approximations (TSAs) and mortar methods to alleviate the need for conforming meshes across the thin layer interfaces. The key steps are:
- The computational domain is divided into external and internal subdomains, with the thin internal layer represented by a thin shell approximation.
- The internal problem is formulated using a tensor product discretization of the thin layer, leading to a 1D FE representation that avoids the need for a volumetric mesh.
- Mortar methods are used to weakly couple the external and internal problems, allowing for non-conforming meshes across the interfaces.
The method is verified by comparing the results to a reference FE solution for a 2D non-linear thermal model of a simplified superconducting accelerator magnet. The mortar TSA solution shows excellent agreement with the reference, while enabling the use of independent discretizations on the two sides of the thin insulation layer.
The paper also discusses the extension of the mortar TSA approach to magnetodynamic formulations. The implementation is publicly available in the open-source finite element framework GetDP.
Stats
The maximum temperature Tmax in the right cable of the reference solution reaches a stationary constant value over time due to the balance between the constant heat source Q and the cryogenic cooling condition.
The relative error of the mortar TSA solution compared to the reference solution is below 10^-4.
Quotes
"The mortar TSA method's formulation is derived and enables an independent discretization of the subdomains on the two sides of the TSA depending on their accuracy requirements."
"The proposed mortar TSA method enables the use of TSAs with non-conforming meshes by combining TSAs with the mortar method."