Imperial College London
Professor Xuesong Wu

ProfessorXuesongWu

Faculty of Natural Sciences, Department of Mathematics

Professor of Applied Mathematics
 
 
 
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Contact

 

+44 (0)20 7594 8494x.wu Website

 
 
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Location

 

738Huxley BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Huang:2017:10.1017/jfm.2017.287,
author = {Huang, Z and Wu, X},
doi = {10.1017/jfm.2017.287},
journal = {Journal of Fluid Mechanics},
pages = {444--483},
title = {A local scattering approach for the effects of abrupt changes on boundary-layer instability and transition: a finite-Reynolds-number formulation for isolated distortions},
url = {http://dx.doi.org/10.1017/jfm.2017.287},
volume = {822},
year = {2017}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We investigate the influence of abrupt changes on boundary-layer instability and transition. Such changes can take different forms including a local porous wall, suction/injection and surface roughness as well as junctions between rigid and porous walls. They may modify the boundary conditions and/or the mean flow, and their effects on transition have usually been assessed by performing stability analysis for the modified base flow and/or boundary conditions. However, such a conventional local linear stability theory (LST) becomes invalid if the change occurs over a relatively short scale comparable with, or even shorter than, the characteristic wavelength of the instability. In this case, the influence on transition is through scattering with the abrupt change acting as a local scatter, that is, an instability mode propagating through the region of abrupt change is scattered by the strong streamwise inhomogeneity to acquire a different amplitude. A local scattering approach (LSA) should be formulated instead, in which a transmission coefficient, defined as the ratio of the amplitude of the instability wave after the scatter to that before, is introduced to characterize the effect on instability and transition. In the present study, we present a finite-Reynolds-number formulation of LSA for isolated changes including a rigid plate interspersed by a local porous panel and a wall suction through a narrow slot. When the weak non-parallelism of the unperturbed base flow is ignored, the local scattering problem can be cast as an eigenvalue problem, in which the transmission coefficient appears as the eigenvalue. We also improved the method to take into account the non-parallelism of the unperturbed base flow, where it is found that the weak non-parallelism has a rather minor effect. The general formulation is specialized to two-dimensional Tollmien–Schlichting (T–S) waves. The resulting eigenvalue problem is solved, and full direct numerical simulations (DNS)
AU  - Huang,Z
AU  - Wu,X
DO  - 10.1017/jfm.2017.287
EP  - 483
PY  - 2017///
SN  - 0022-1120
SP  - 444
TI  - A local scattering approach for the effects of abrupt changes on boundary-layer instability and transition: a finite-Reynolds-number formulation for isolated distortions
T2  - Journal of Fluid Mechanics
UR  - http://dx.doi.org/10.1017/jfm.2017.287
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000403090300025&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - http://hdl.handle.net/10044/1/64142
VL  - 822
ER  -
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