Draft: Implement Nitsche method to couple embedded meshes#1613
Draft
eulovi wants to merge 16 commits into4C-multiphysics:mainfrom
Draft
Draft: Implement Nitsche method to couple embedded meshes#1613eulovi wants to merge 16 commits into4C-multiphysics:mainfrom
eulovi wants to merge 16 commits into4C-multiphysics:mainfrom
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eulovi
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status: in progress
amgebauer
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Dec 18, 2025
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isteinbrecher
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isteinbrecher
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Thanks for the new functionality @eulovi .
I did not have time to go through everything in detail, but I left some general comments.
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| Core::LinAlg::SparseMatrix& global_penalty_interface, | ||
| Core::LinAlg::SparseMatrix& global_penalty_background, | ||
| Core::LinAlg::SparseMatrix& global_penalty_interface_background, | ||
| Core::LinAlg::SparseMatrix& global_disp_interface_stress_interface, | ||
| Core::LinAlg::SparseMatrix& global_disp_interface_stress_background, | ||
| Core::LinAlg::SparseMatrix& global_disp_background_stress_interface, | ||
| Core::LinAlg::SparseMatrix& global_disp_background_stress_background, | ||
| Core::LinAlg::FEVector<double>& global_constraint, double& nitsche_stabilization_param, |
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I am not so sure about this interface. Why do we need so many matrices? Nitsches method should be like the penalty method, so I would assume that we only need to assemble in the global stiffness matrix and force vector.
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| //! Couple strategy between overlapping and underlying meshes | ||
| Constraints::EmbeddedMesh::EmbeddedMeshParams embedded_mesh_coupling_params_; | ||
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| //! Pointer to the mortar manager. This object stores the relevant mortar matrices. | ||
| std::shared_ptr<Constraints::EmbeddedMesh::SolidToSolidMortarManager> mortar_manager_; | ||
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| //! Pointer to the Nitsche manager. | ||
| std::shared_ptr<Constraints::EmbeddedMesh::SolidToSolidNitscheManager> nitsche_manager_; |
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Instead of #1614 you can move the common functionality of the mortar and nitsche manager into this submode evaluator and not require the two to be based on the same base class.
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Description and Context
In this PR, a non-symmetric Nitsche method is implemented for coupling embedded meshes. This is introduced in the constraint_framework library. For now, I set this as a draft, as there is redundancy in the code and I might have broke some tests from the mortar coupling.
The general strategy for introducing this functionality is the following:
evaluate_global_coupling_contributionsandadd_global_force_stiffness_contributions. Maybe I could do a base class, called coupling_manager that hold the functionality of defining the pairs and doing the setup and define the subclasses ofmortar_managerandnitsche_managerthat have their ownevaluate_global_coupling_contributionsandadd_global_force_stiffness_contributions. Although I am open to ideas.As there is a lot going on here, some clean up should be done in other PRs before merging this one:
get_normal_cauchy_stress_at_xiand to the functions that call it.Related Issues and Pull Requests