Abstract
We recall one set of possible basis vector fields and two different sets of possible degrees of freedom, those related to “small-edges” and those defined by “moments”, for the Nédélec’s first family of high order edge elements. We thus address a dispersion analysis of the resulting methods, when the time-harmonic Maxwell’s equation for the electric field is discretized on a simplicial mesh.
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Notes
- 1.
In two spatial dimensions, say x, y, we denote by ∂ x (resp. ∂ y ) the first order operator that associates any differentiable scalar function g with its partial derivative ∂ x g (resp. ∂ y g) w.r.t. the variable x (resp. y). For any vector field \(\mathbf{u} \in \mathbb{R}^{2}\), with u = (u x , u y )⊤, we define f = curl u such as the scalar function f = ∂ x u y − ∂ y u x ; for any scalar function v ∈ IR, we define w = curl v such as the vector field w = (∂ y v, −∂ x v)⊤. Note that curl v = (grad v)⊥, where g = grad v = (∂ x v, ∂ y v)⊤.
- 2.
The definition of Whitney forms relies on duality features from algebraic topology. Let w e be the Whitney edge forms, where e belongs to the set of mesh edges \(\mathcal{E}\). A field v, represented by the 1-form ∑ e v e w e, with v e = ∫ e v, and a curve γ, represented by the 1-chain ∑ e α e e, with α e = ∫ γ w e, are in duality via the formula \(\int _{\gamma }\mathrm{v} =\sum _{e\in \mathcal{E}}\alpha _{e}\,\mathrm{v}_{e}\). What is meant by in duality is that ∫ γ v = 0 \(\ \forall \gamma\) implies v = 0 and the other way around. Duality stems from the property of edge elements, ∫ e′ w e = δ e′ e . Note that the same forms w e are involved in the description of both fields and curves: this duality is the key to understand why Whitney elements have the expression they have [3].
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Acknowledgements
The authors acknowledge the French National Research Agency (ANR) for its financial support (project MEDIMAX, ANR-13-MONU-0012). The last author warmly thanks the Università degli Studi di Verona for the possibility of studying as ERASMUS fellow at the Université Côte Azur in Nice.
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Bonazzoli, M., Rapetti, F., Tournier, PH., Venturini, C. (2017). High Order Edge Elements for Electromagnetic Waves: Remarks on Numerical Dispersion. In: Bittencourt, M., Dumont, N., Hesthaven, J. (eds) Spectral and High Order Methods for Partial Differential Equations ICOSAHOM 2016. Lecture Notes in Computational Science and Engineering, vol 119. Springer, Cham. https://doi.org/10.1007/978-3-319-65870-4_14
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DOI: https://doi.org/10.1007/978-3-319-65870-4_14
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