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Main Authors: Zheng, Nan, Guo, Xu, Pei, Wenlong, Zhao, Wenju
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.21392
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author Zheng, Nan
Guo, Xu
Pei, Wenlong
Zhao, Wenju
author_facet Zheng, Nan
Guo, Xu
Pei, Wenlong
Zhao, Wenju
contents This paper is concerned with mixed finite element method (FEM) for solving the two-dimensional, nonlinear fourth-order active fluid equations. By introducing an auxiliary variable $w=-Δu$, the original fourth problem is transformed into a system of second-order equations, which relaxes the regularity requirements of standard $H^2$-conforming finite spaces. To further enhance the robustness and efficiency of the algorithm, an additional auxiliary variable $ϕ$, treated analogously to the pressure, is introduced, leading to a divergence-free preserving mixed finite element scheme. A fully discrete scheme is then constructed by coupling the spatial mixed FEM with the variable-step Dahlquist-Liniger-Nevanlinna (DLN) time integrator. The boundedness of the scheme and corresponding error estimates can be rigorously proven under appropriate assumptions due to unconditional non-linear stability and second-order accuracy of the DLN method. To enhance computational efficiency in practice, we develop an adaptive time-stepping strategy based on a minimum-dissipation criterion. Several numerical experiments are displayed to fully validate the theoretical results and demonstrate the accuracy and efficiency of the scheme for complex active fluid simulations.
format Preprint
id arxiv_https___arxiv_org_abs_2507_21392
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Divergence-free Preserving Mix Finite Element Methods for Fourth-order Active Fluid Model
Zheng, Nan
Guo, Xu
Pei, Wenlong
Zhao, Wenju
Numerical Analysis
This paper is concerned with mixed finite element method (FEM) for solving the two-dimensional, nonlinear fourth-order active fluid equations. By introducing an auxiliary variable $w=-Δu$, the original fourth problem is transformed into a system of second-order equations, which relaxes the regularity requirements of standard $H^2$-conforming finite spaces. To further enhance the robustness and efficiency of the algorithm, an additional auxiliary variable $ϕ$, treated analogously to the pressure, is introduced, leading to a divergence-free preserving mixed finite element scheme. A fully discrete scheme is then constructed by coupling the spatial mixed FEM with the variable-step Dahlquist-Liniger-Nevanlinna (DLN) time integrator. The boundedness of the scheme and corresponding error estimates can be rigorously proven under appropriate assumptions due to unconditional non-linear stability and second-order accuracy of the DLN method. To enhance computational efficiency in practice, we develop an adaptive time-stepping strategy based on a minimum-dissipation criterion. Several numerical experiments are displayed to fully validate the theoretical results and demonstrate the accuracy and efficiency of the scheme for complex active fluid simulations.
title Divergence-free Preserving Mix Finite Element Methods for Fourth-order Active Fluid Model
topic Numerical Analysis
url https://arxiv.org/abs/2507.21392