Pulsatile Flows for Simplified Smart Fluids with Variable Power-Law: Analysis and Numerics

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Main Authors: Berselli, Luigi C., Kaltenbach, Alex
Format: Preprint
Published: 2025
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author Berselli, Luigi C.
Kaltenbach, Alex
author_facet Berselli, Luigi C.
Kaltenbach, Alex
contents We study the fully-developed, time-periodic motion of a shear-dependent non-Newtonian fluid with variable exponent rheology through an infinite pipe $Ω:= \mathbb{R}\times Σ\subseteq \mathbb{R}^d$, $d\in \{2,3\}$, of arbitrary cross-section $Σ\subseteq \mathbb{R}^{d-1}$. The focus is on a generalized $p(\cdot)$-fluid model, where the power-law index is position-dependent (with respect to $Σ$), $\textit{i.e.}$, a function $p\colon Σ\to (1,+\infty)$. We prove the existence of time-periodic solutions with either assigned time-periodic flow-rate or pressure-drop, generalizing known results for the Navier-Stokes and for $p$-fluid equations. In addition, we identify explicit solutions, relevant as benchmark cases, especially for electro-rheological fluids or, more generally, $\textit{`smart fluids'}$. To support practical applications, we present a fully-constructive existence proof for variational solutions by means of a fully-discrete finite-differences/-elements discretization, consistent with our numerical experiments. Our approach, which unifies the treatment of all values of $p(\overline{x})\in (1,+\infty)$, $\overline{x}\in Σ$, without requiring an auxiliary Newtonian term, provides new insights even in the constant exponent case. The theoretical findings are reviewed by means of numerical experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2507_22449
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Pulsatile Flows for Simplified Smart Fluids with Variable Power-Law: Analysis and Numerics
Berselli, Luigi C.
Kaltenbach, Alex
Numerical Analysis
Analysis of PDEs
35Q35, 76A05, 76D05, 65M60, 35D30, 35K55, 35B10, 76M10, 35Q30
We study the fully-developed, time-periodic motion of a shear-dependent non-Newtonian fluid with variable exponent rheology through an infinite pipe $Ω:= \mathbb{R}\times Σ\subseteq \mathbb{R}^d$, $d\in \{2,3\}$, of arbitrary cross-section $Σ\subseteq \mathbb{R}^{d-1}$. The focus is on a generalized $p(\cdot)$-fluid model, where the power-law index is position-dependent (with respect to $Σ$), $\textit{i.e.}$, a function $p\colon Σ\to (1,+\infty)$. We prove the existence of time-periodic solutions with either assigned time-periodic flow-rate or pressure-drop, generalizing known results for the Navier-Stokes and for $p$-fluid equations. In addition, we identify explicit solutions, relevant as benchmark cases, especially for electro-rheological fluids or, more generally, $\textit{`smart fluids'}$. To support practical applications, we present a fully-constructive existence proof for variational solutions by means of a fully-discrete finite-differences/-elements discretization, consistent with our numerical experiments. Our approach, which unifies the treatment of all values of $p(\overline{x})\in (1,+\infty)$, $\overline{x}\in Σ$, without requiring an auxiliary Newtonian term, provides new insights even in the constant exponent case. The theoretical findings are reviewed by means of numerical experiments.
title Pulsatile Flows for Simplified Smart Fluids with Variable Power-Law: Analysis and Numerics
topic Numerical Analysis
Analysis of PDEs
35Q35, 76A05, 76D05, 65M60, 35D30, 35K55, 35B10, 76M10, 35Q30
url https://arxiv.org/abs/2507.22449