Imperial College London


Faculty of EngineeringDepartment of Aeronautics

Professor of Computational Fluid Mechanics



+44 (0)20 7594 5052s.sherwin Website




313BCity and Guilds BuildingSouth Kensington Campus






BibTex format

author = {Cooke, EE and Mughal, MS and Sherwin, S and Ashworth, R and Rolston, S},
doi = {10.2514/6.2019-3533},
publisher = {American Institute of Aeronautics and Astronautics},
title = {Destabilisation of Stationary and Travelling Crossflow Disturbances Due to Steps over a Swept Wing},
url = {},
year = {2019}

RIS format (EndNote, RefMan)

AB - Destabilization effects of forward facing steps, backward facing steps and bumps on stationary and travelling crossflow disturbances are investigated computationally for a 40° infinite swept wing. Step and bump heights range from 24% to 53% of the boundary layer thickness and are located at 10% chord. The spectral/hp element solver, Nektar++, is used to compute base flow profiles with an embedded swept wing geometry. Parabolized Stability Equations (PSE) and Linearized Harmonic Navier-Stokes (LHNS) models are used to evaluate growth of convecting instabilities. The paper describes derivations of the PSE and LHNS models which accurately solve for the perturbed field over the very localized and rapid variations imposed by the surface step-features. Unlike the PSE, which suffer from a stream-wise numerical step size restriction, the LHNS are a fully elliptic set of equations which may use arbitrarily fine grid resolution. Unsurprisingly, the PSE codes fail to capture the effect of abrupt changes in surface geometry introduced by the steps features. Results for the LHNS and roughness incorporating LHNS are given for the varying step types. Comparisons are made between the LHNS model and direct numerical simulations involving the time-stepping linearized Navier-Stokes solver in the Nektar++ software suite. Most previous work in the topic area has focused on Tollmien-Schlichting perturbations over two-dimensional flat plate flows or airfoils, the novelty of this work lies with analyzing crossflow instability over a swept wing boundary-layer flow with step features.
AU - Cooke,EE
AU - Mughal,MS
AU - Sherwin,S
AU - Ashworth,R
AU - Rolston,S
DO - 10.2514/6.2019-3533
PB - American Institute of Aeronautics and Astronautics
PY - 2019///
TI - Destabilisation of Stationary and Travelling Crossflow Disturbances Due to Steps over a Swept Wing
UR -
UR -
ER -