Convex-concave splitting for the Allen-Cahn equation leads to $\varepsilon^2$-slow movement of interfaces

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Main Authors: Dondl, Patrick, Onwunta, Akwum, Striet, Ludwig, Wojtowytsch, Stephan
Format: Preprint
Published: 2025
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_version_ 1866913908072120320
author Dondl, Patrick
Onwunta, Akwum
Striet, Ludwig
Wojtowytsch, Stephan
author_facet Dondl, Patrick
Onwunta, Akwum
Striet, Ludwig
Wojtowytsch, Stephan
contents The convex-concave splitting discretization of the Allen-Cahn is easy to implement and guaranteed to be energy decreasing even for large time-steps. We analyze the time-stepping scheme for a large class of potentials which includes the standard potential as well as two extreme settings: Potentials with quadratic convex part (uniform positive curvature), and potentials which are concave between the potential wells and either linear or infinite outside (highly concentrated curvature). In all three scenarios, the 'effective time step size' of the scheme scales with the square of the small parameter $\varepsilon$ governing the width of transition layers. A weaker 'slow motion' result is proved under much more general assumptions. Thus, stability is achieved by effectively 'freezing' the interfaces in place. The time step limitation is not geometric in origin, but depends on the phase-field parameter $\varepsilon$. Along the way, we establish a new link between an Allen-Cahn type equation and a thresholding approximation of mean curvature flow.
format Preprint
id arxiv_https___arxiv_org_abs_2506_18869
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Convex-concave splitting for the Allen-Cahn equation leads to $\varepsilon^2$-slow movement of interfaces
Dondl, Patrick
Onwunta, Akwum
Striet, Ludwig
Wojtowytsch, Stephan
Numerical Analysis
Analysis of PDEs
65M12, 35A35, 49Q05
The convex-concave splitting discretization of the Allen-Cahn is easy to implement and guaranteed to be energy decreasing even for large time-steps. We analyze the time-stepping scheme for a large class of potentials which includes the standard potential as well as two extreme settings: Potentials with quadratic convex part (uniform positive curvature), and potentials which are concave between the potential wells and either linear or infinite outside (highly concentrated curvature). In all three scenarios, the 'effective time step size' of the scheme scales with the square of the small parameter $\varepsilon$ governing the width of transition layers. A weaker 'slow motion' result is proved under much more general assumptions. Thus, stability is achieved by effectively 'freezing' the interfaces in place. The time step limitation is not geometric in origin, but depends on the phase-field parameter $\varepsilon$. Along the way, we establish a new link between an Allen-Cahn type equation and a thresholding approximation of mean curvature flow.
title Convex-concave splitting for the Allen-Cahn equation leads to $\varepsilon^2$-slow movement of interfaces
topic Numerical Analysis
Analysis of PDEs
65M12, 35A35, 49Q05
url https://arxiv.org/abs/2506.18869