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arXiv · 2606.31662

Positivity-preserving dynamical low-rank methods for the Vlasov equation

Katharina Kormann·Murtazo Nazarov·Junjie Wen
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Abstract

In this manuscript, we introduce positivity-preserving correction methods for low-rank approximations of the Vlasov equation. The key idea is to formulate structural properties, including positivity-preservation, as constraints and to seek a minimal correction term that is added to the low-rank solution, by solving a quadratic programming problem. As a result, the corrected solution satisfies the constraints and preserve these properties, while remaining close to the original low-rank solution. Two positivity-preserving schemes are proposed in this work, and one of them also preserves the total mass and momentum of the system. We apply the proposed methods to a Vlasov--Poisson and Vlasov--Poisson-BGK employing a spectral discretization in space and an explicit Runge--Kutta scheme in time. Numerical experiments demonstrate the effectiveness of the proposed methods.

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Katharina Kormann, Murtazo Nazarov, Junjie Wen. 2026-06-30. Positivity-preserving dynamical low-rank methods for the Vlasov equation. https://arxiv.org/abs/2606.31662

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