$\textit{A Priori}$ Error Analysis for the $p$-Stokes Equations with Slip Boundary Conditions: A Discrete Leray Projection Framework

Fuente: arXiv
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Main Authors: Kaltenbach, Alex, Wichmann, Jörn
Format: Preprint
Published: 2025
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_version_ 1866918181255249920
author Kaltenbach, Alex
Wichmann, Jörn
author_facet Kaltenbach, Alex
Wichmann, Jörn
contents We present an $\textit{a priori}$ error analysis for the kinematic pressure in a fully-discrete finite-differences/-elements discretization of the unsteady $p$-Stokes equations, modelling non-Newtonian fluids. This system is subject to both impermeability and perfect Navier slip boundary conditions, which are incorporated either weakly via Lagrange multipliers or strongly in the discrete velocity space. A central aspect of the $\textit{a priori}$ error analysis is the discrete Leray projection, constructed to quantitatively approximate its continuous counterpart. The discrete Leray projection enables a Helmholtz-type decomposition at the discrete level and plays a key role in deriving error decay rates for the kinematic pressure. We derive (in some cases optimal) error decay rates for both the velocity vector field and kinematic pressure, with the error for the kinematic pressure measured in an $\textit{ad hoc}$ norm informed by the projection framework. The $\textit{a priori}$ error analysis remains robust even under reduced regularity of the velocity vector field and the kinematic pressure, and illustrates how the interplay of boundary conditions and projection stability governs the accuracy of pressure approximations.
format Preprint
id arxiv_https___arxiv_org_abs_2507_15016
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle $\textit{A Priori}$ Error Analysis for the $p$-Stokes Equations with Slip Boundary Conditions: A Discrete Leray Projection Framework
Kaltenbach, Alex
Wichmann, Jörn
Numerical Analysis
65M60, 76A05, 35Q35, 76D07, 65M15, 35B45
We present an $\textit{a priori}$ error analysis for the kinematic pressure in a fully-discrete finite-differences/-elements discretization of the unsteady $p$-Stokes equations, modelling non-Newtonian fluids. This system is subject to both impermeability and perfect Navier slip boundary conditions, which are incorporated either weakly via Lagrange multipliers or strongly in the discrete velocity space. A central aspect of the $\textit{a priori}$ error analysis is the discrete Leray projection, constructed to quantitatively approximate its continuous counterpart. The discrete Leray projection enables a Helmholtz-type decomposition at the discrete level and plays a key role in deriving error decay rates for the kinematic pressure. We derive (in some cases optimal) error decay rates for both the velocity vector field and kinematic pressure, with the error for the kinematic pressure measured in an $\textit{ad hoc}$ norm informed by the projection framework. The $\textit{a priori}$ error analysis remains robust even under reduced regularity of the velocity vector field and the kinematic pressure, and illustrates how the interplay of boundary conditions and projection stability governs the accuracy of pressure approximations.
title $\textit{A Priori}$ Error Analysis for the $p$-Stokes Equations with Slip Boundary Conditions: A Discrete Leray Projection Framework
topic Numerical Analysis
65M60, 76A05, 35Q35, 76D07, 65M15, 35B45
url https://arxiv.org/abs/2507.15016