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Leitenmaier, L. & Nazarov, M. (2023). A finite element based heterogeneous multiscale method for the Landau-Lifshitz equation. Journal of Computational Physics, 486, Article ID 112112.
Open this publication in new window or tab >>A finite element based heterogeneous multiscale method for the Landau-Lifshitz equation
2023 (English)In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 486, article id 112112Article in journal (Refereed) Published
Abstract [en]

We present a Heterogeneous Multiscale Method for the Landau-Lifshitz equation with a highly oscillatory diffusion coefficient, a simple model for a ferromagnetic composite. A finite element macro scheme is combined with a finite difference micro model to approximate the effective equation corresponding to the original problem. This makes it possible to obtain effective solutions to problems with rapid material variations on a small scale, described by ε≪1, which would be too expensive to resolve in a conventional simulation.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Finite element method, Heterogeneous Multiscale Methods, Micromagnetics
National Category
Computational Mathematics
Identifiers
urn:nbn:se:kth:diva-330918 (URN)10.1016/j.jcp.2023.112112 (DOI)001055134200001 ()2-s2.0-85152241906 (Scopus ID)
Note

QC 20230704

Available from: 2023-07-04 Created: 2023-07-04 Last updated: 2023-11-30Bibliographically approved
Leitenmaier, L. & Runborg, O. (2022). Heterogeneous Multiscale Methods for the Landau–Lifshitz Equation. Journal of Scientific Computing, 93(3), Article ID 76.
Open this publication in new window or tab >>Heterogeneous Multiscale Methods for the Landau–Lifshitz Equation
2022 (English)In: Journal of Scientific Computing, ISSN 0885-7474, E-ISSN 1573-7691, Vol. 93, no 3, article id 76Article in journal (Refereed) Published
Abstract [en]

In this paper, we present a finite difference Heterogeneous Multiscale Method for the Landau–Lifshitz equation with a highly oscillatory diffusion coefficient. The approach combines a higher order discretization and artificial damping in the so-called micro problem to obtain an efficient implementation. The influence of different parameters on the resulting approximation error is discussed. Further important factors that are taken into account are the choice of time integrator and the initial data for the micro problem which has to be set appropriately to get a consistent scheme. Numerical examples in one and two space dimensions and for both periodic as well as more general coefficients are given to demonstrate the functionality of the approach.

Place, publisher, year, edition, pages
Springer Nature, 2022
Keywords
Finite differences, Heterogeneous Multiscale Methods, Landau–Lifshitz, Micromagnetics, Nonlinear equations, Partial differential equations, Approximation errors, Artificial damping, Efficient implementation, Finite difference, Finite difference heterogeneous multiscale methods, Heterogeneous multiscale method, Higher order discretization, Landau Lifshitz equation, Landau-Lifshitz, Numerical methods
National Category
Computational Mathematics
Identifiers
urn:nbn:se:kth:diva-328919 (URN)10.1007/s10915-022-01992-8 (DOI)000880353700003 ()2-s2.0-85141479487 (Scopus ID)
Note

QC 20230613

Available from: 2023-06-13 Created: 2023-06-13 Last updated: 2023-06-13Bibliographically approved
Leitenmaier, L. & Runborg, O. (2022). On homogenization of the Landau-Lifshitz equation with rapidly oscillating material coefficient. Communications in Mathematical Sciences, 20(3), 653-694
Open this publication in new window or tab >>On homogenization of the Landau-Lifshitz equation with rapidly oscillating material coefficient
2022 (English)In: Communications in Mathematical Sciences, ISSN 1539-6746, E-ISSN 1945-0796, Vol. 20, no 3, p. 653-694Article in journal (Refereed) Published
Abstract [en]

In this paper, we consider homogenization of the Landau-Lifshitz equation with a highly oscillatory material coefficient with period epsilon modeling a ferromagnetic composite. We derive equations for the homogenized solution to the problem and the corresponding correctors and obtain estimates for the difference between the exact and homogenized solution as well as corrected approximations to the solution. Convergence rates in epsilon over times O(epsilon(sigma)) with 0 <= sigma <= 2 are given in the Sobolev norm H-q, where q is limited by the regularity of the solution to the detailed Landau-Lifshitz equation and the homogenized equation. The rates depend on q, sigma and the number of correctors.

Place, publisher, year, edition, pages
International Press of Boston, Inc., 2022
Keywords
Homogenization, micromagnetics, magnetization dynamics, multiscale
National Category
Mathematical Analysis
Identifiers
urn:nbn:se:kth:diva-311035 (URN)10.4310/CMS.2022.v20.n3.a3 (DOI)000776355400003 ()2-s2.0-85128299475 (Scopus ID)
Note

Not duplicate with DiVA 1611059

QC 20220421

Available from: 2022-04-21 Created: 2022-04-21 Last updated: 2022-06-25Bibliographically approved
Leitenmaier, L. & Runborg, O. (2022). Upscaling errors in Heterogeneous Multiscale Methods for the Landau-Lifshitz equation. Multiscale Modeling & simulation, 20(1), 1-35
Open this publication in new window or tab >>Upscaling errors in Heterogeneous Multiscale Methods for the Landau-Lifshitz equation
2022 (English)In: Multiscale Modeling & simulation, ISSN 1540-3459, E-ISSN 1540-3467, Vol. 20, no 1, p. 1-35Article in journal (Refereed) Published
Abstract [en]

In this paper, we consider several possible ways to set up Heterogeneous Multiscale Methods for the Landau-Lifshitz equation with a highly oscillatory diffusion coefficient, which can be seen as a means to modeling rapidly varying ferromagnetic materials. We then prove estimates for the errors introduced when approximating the relevant quantity in each of the models given a periodic problem, using averaging in time and space of the solution to a corresponding micro problem. In our setup, the Landau-Lifshitz equation with a highly oscillatory coefficient is chosen as the micro problem for all models. We then show that the averaging errors only depend on \varepsilon and the size of the microscopic oscillations, as well as the size of the averaging domain in time and space and the choice of averaging kernels.

Place, publisher, year, edition, pages
Society for Industrial & Applied Mathematics (SIAM), 2022
Keywords
&nbsp, heterogeneous multiscale methods, micromagnetics, magnetization dynamics
National Category
Computational Mathematics
Identifiers
urn:nbn:se:kth:diva-310029 (URN)10.1137/21M1409408 (DOI)000760284700001 ()2-s2.0-85130574540 (Scopus ID)
Note

QC 20220323

No duplicate with DiVA 1611064

Available from: 2022-03-23 Created: 2022-03-23 Last updated: 2023-02-21Bibliographically approved
Leitenmaier, L. & Runborg, O. (2021). On homogenization of the Landau-Lifshitz equation with rapidly oscillating material coefficient. Communications in Mathematical Sciences
Open this publication in new window or tab >>On homogenization of the Landau-Lifshitz equation with rapidly oscillating material coefficient
2021 (English)In: Communications in Mathematical Sciences, ISSN 1539-6746, E-ISSN 1945-0796Article in journal (Refereed) Accepted
Abstract [en]

In this paper, we consider homogenization of the Landau-Lifshitz equation with a highly oscillatory material coefficient with period ε modeling a ferromagnetic composite. We derive equations for the homogenized solution to the problem and the corresponding correctors and obtain estimates for the difference between the exact and homogenized solution as well as corrected approximations to the solution. Convergence rates in ε over times O(εσ) with 0 ≤ σ ≤ 2 are given in the Sobolev norm Hq , where q is limited by the regularity of the solution to the detailed Landau-Lifshitz equation and the homogenized equation. The rates depend on q, σ and the number of correctors.

Keywords
Homogenization; Micromagnetics; Magnetization Dynamics; Multiscale
National Category
Mathematics
Identifiers
urn:nbn:se:kth:diva-304805 (URN)
Note

QC 20211123

Available from: 2021-11-12 Created: 2021-11-12 Last updated: 2022-06-25Bibliographically approved
Leitenmaier, L. & Nazarov, M. A finite element based Heterogeneous Multiscale Method for the Landau-Lifshitz equation.
Open this publication in new window or tab >>A finite element based Heterogeneous Multiscale Method for the Landau-Lifshitz equation
(English)In: Article in journal (Other academic) Submitted
Abstract [en]

We present a Heterogeneous Multiscale Method for the Landau-Lifshitz equation with a highly oscillatory diffusion coefficient, a simple model for a ferromagnetic composite. A finite element macro scheme is combined with a finite difference micro model to approximate the effective equation corresponding to the original problem. This makes it possible to obtain effective solutions to problems with rapid material variations on a small scale, described by ε << 1, which would be too expensive to resolve in a conventional simulation.

Keywords
Micromagnetics; Heterogeneous Multiscale Methods; Finite element method
National Category
Computational Mathematics
Research subject
Applied and Computational Mathematics, Numerical Analysis
Identifiers
urn:nbn:se:kth:diva-304810 (URN)
Note

QC 20211123

Available from: 2021-11-12 Created: 2021-11-12 Last updated: 2022-06-25Bibliographically approved
Leitenmaier, L. & Runborg, O. Heterogeneous Multiscale Methods for the Landau-Lifshitz equation.
Open this publication in new window or tab >>Heterogeneous Multiscale Methods for the Landau-Lifshitz equation
(English)In: Article in journal (Other academic) Submitted
Abstract [en]

In this paper, we present a finite difference Heterogeneous Multiscale Method for the Landau-Lifshitz equation with a highly oscillatory diffusion coefficient. The approach combines a higher order discretization and artificial damping in the so-called micro problem to obtain an efficient implementation. The influence of different parameters on the resulting approximation error is discussed. Numerical examples for both periodic as well as more general coefficients are given to demonstrate the functionality of the approach.

Keywords
Heterogeneous Multiscale Methods; Micromagnetics;
National Category
Computational Mathematics
Identifiers
urn:nbn:se:kth:diva-304809 (URN)
Note

QC 20211123

Available from: 2021-11-12 Created: 2021-11-12 Last updated: 2022-06-25Bibliographically approved
Leitenmaier, L. & Runborg, O. Upscaling errors in Heterogeneous Multiscale Methods for the Landau-Lifshitz equation. Multiscale Modeling & simulation
Open this publication in new window or tab >>Upscaling errors in Heterogeneous Multiscale Methods for the Landau-Lifshitz equation
(English)In: Multiscale Modeling & simulation, ISSN 1540-3459, E-ISSN 1540-3467Article in journal (Refereed) Accepted
Abstract [en]

In this paper, we consider several possible ways to set up Heterogeneous Multiscale Methods for the Landau-Lifshitz equation with a highly oscillatory diffusion coefficient, which can be seen as a means to modeling rapidly varying ferromagnetic materials. We then prove estimates for the errors introduced when approximating the relevant quantity in each of the models given a periodic problem, using averaging in time and space of the solution to a corresponding micro problem. In our setup, the Landau-Lifshitz equation with highly oscillatory coefficient is chosen as the micro problem for all models. We then show that the averaging errors only depend on ε, the size of the microscopic oscillations, as well as the size of the averaging domain in time and space and the choice of averaging kernels.

Keywords
Heterogeneous Multiscale Methods; Micromagnetics; Magnetization Dynamics;
National Category
Computational Mathematics
Research subject
Applied and Computational Mathematics, Numerical Analysis
Identifiers
urn:nbn:se:kth:diva-304808 (URN)
Note

QC 20211123

Available from: 2021-11-12 Created: 2021-11-12 Last updated: 2022-06-25Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2348-1479

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