Order Conditions for Nonlinearly Partitioned Runge-Kutta Methods

Fuente: arXiv
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Auteurs principaux: Tran, Brian K., Southworth, Ben S., Buvoli, Tommaso
Format: Preprint
Publié: 2024
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author Tran, Brian K.
Southworth, Ben S.
Buvoli, Tommaso
author_facet Tran, Brian K.
Southworth, Ben S.
Buvoli, Tommaso
contents Recently a new class of nonlinearly partitioned Runge--Kutta (NPRK) methods was proposed for nonlinearly partitioned systems of autonomous ordinary differential equations, $y' = F(y,y)$. The target class of problems are ones in which different scales, stiffnesses, or physics are coupled in a nonlinear way, wherein the desired partition cannot be written in a classical additive or component-wise fashion. Here we use rooted-tree analysis to derive full order conditions for NPRK$_M$ methods, where $M$ denotes the number of nonlinear partitions. Due to the nonlinear coupling and thereby mixed product differentials, it turns out the standard node-colored rooted-tree analysis used in analyzing ODE integrators does not naturally apply. Instead we develop a new edge-colored rooted-tree framework to address the nonlinear coupling. The resulting order conditions are enumerated, provided directly for up to 4th order with $M=2$ and 3rd-order with $M=3$, and related to existing order conditions of additive and partitioned RK methods. We conclude with an example which shows how the nonlinear order conditions can be used to obtain an embedded estimate of the state-dependent nonlinear coupling strength in a dynamical system.
format Preprint
id arxiv_https___arxiv_org_abs_2401_12427
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Order Conditions for Nonlinearly Partitioned Runge-Kutta Methods
Tran, Brian K.
Southworth, Ben S.
Buvoli, Tommaso
Numerical Analysis
Recently a new class of nonlinearly partitioned Runge--Kutta (NPRK) methods was proposed for nonlinearly partitioned systems of autonomous ordinary differential equations, $y' = F(y,y)$. The target class of problems are ones in which different scales, stiffnesses, or physics are coupled in a nonlinear way, wherein the desired partition cannot be written in a classical additive or component-wise fashion. Here we use rooted-tree analysis to derive full order conditions for NPRK$_M$ methods, where $M$ denotes the number of nonlinear partitions. Due to the nonlinear coupling and thereby mixed product differentials, it turns out the standard node-colored rooted-tree analysis used in analyzing ODE integrators does not naturally apply. Instead we develop a new edge-colored rooted-tree framework to address the nonlinear coupling. The resulting order conditions are enumerated, provided directly for up to 4th order with $M=2$ and 3rd-order with $M=3$, and related to existing order conditions of additive and partitioned RK methods. We conclude with an example which shows how the nonlinear order conditions can be used to obtain an embedded estimate of the state-dependent nonlinear coupling strength in a dynamical system.
title Order Conditions for Nonlinearly Partitioned Runge-Kutta Methods
topic Numerical Analysis
url https://arxiv.org/abs/2401.12427