Dear Spiral user, We’re pleased to introduce Helix, https://helix.imperial.ac.uk/ Imperial’s new repository for research datasets. Please use Helix for all future dataset deposits. There is no change to Spiral - continue depositing as usual. For queries, contact the Research Data Management team at rdm-enquiries@imperial.ac.uk. Kind regards, the Spiral Team. The Spiral team
A solution for the quasi-one-dimensional linearised Euler equations with wall friction
File(s)
Author(s)
Hu, Xiao
Morgans, Aimee
Yeddula, Saikumar Reddy
Type
Journal Article
Abstract
The unsteady response of nozzles with wall friction forced by acoustic and/or entropy waves is modelled. The approach is based on the quasi-one-dimensional linearised Euler equations. The equations are cast in terms of three variables, namely the dimensionless mass, stagnation temperature and entropy fluctuations, which are invariants of the system at zero frequency and in the absence of wall friction. The resulting first-order system of differential equations is solved using the Magnus-expansion method, where the perturbation parameters are the normalised frequencies and Fanning friction factors. In this work, a measure of the flow non-isentropicity caused by wall friction is used for the first time as an expansion parameter. The solution method is applied to a converging–diverging nozzle with wall friction for both subsonic and supersonic flow cases, showing good agreement with numerical predictions. The nozzle flow with both wall friction and steady heat transfer is further explored. It is observed that the acoustic and entropy transfer functions of the nozzle strongly depend on the frequency, wall friction and heat transfer. Wall friction affects the unsteady response through changes in the mean flow and through coupling between acoustic, velocity and entropy fluctuations.
Date Issued
2026-06-25
Date Acceptance
2026-05-23
Citation
Journal of Fluid Mechanics, 2026, 1037
URI
DOI
ISSN
0022-1120
Publisher
Cambridge University Press
Journal / Book Title
Journal of Fluid Mechanics
Volume
1037
Copyright Statement
© The Author(s), 2026. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
License URL
Identifier
10.1017/jfm.2026.11729
Publication Status
Published
Article Number
ARTN A42
Date Publish Online
2025-06-17