Imperial College London
Alternate

ProfessorGeorgePapadakis

Faculty of Engineering, Department of Aeronautics

Professor of Aerodynamics
 
 
 
//

Contact

 

+44 (0)20 7594 5080g.papadakis

 
 
//

Location

 

331City and Guilds BuildingSouth Kensington Campus

//

Summary

 

Publications

Citation

BibTex format

@article{Thomareis:2018:10.1103/PhysRevFluids.3.073901,
author = {Thomareis, N and Papadakis, G},
doi = {10.1103/PhysRevFluids.3.073901},
journal = {Physical Review Fluids},
title = {Resolvent analysis of separated and attached flows around anairfoil at transitional Reynolds number},
url = {http://dx.doi.org/10.1103/PhysRevFluids.3.073901},
volume = {3},
year = {2018}
}
Download

RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We analyze the resolvent operator in three flows around a nominal NACA-0012 airfoil at ReC=50,000and 5 angle of attack. In particular, we study two naturally developing flows (around the airfoil with straight and blunt trailing edges) and one tripped flow. The naturally developing flows exhibit laminar separation, transition and turbulent reattachment, while the tripped flow remains attached in the suction side. For all cases, the time-averaged flow fields are computed from separate DNS simulations. The resolvent analysis can identify the areas of maximum receptivity of the flow field as well as the most amplified modes (optimal response). The former was located close to the leading edge, and in the case of naturally developing flows, also in the free-stream. The spatial distribution of optimal forcing was dominated by structures tilted against the mean flow, in agreement with other studies of boundary layer flows. The optimal response of the two naturally developing flows were different. For the NACA-0012 airfoil with straight trailing edge, the response was maximized at the natural frequency of the separating shear layer, and the shape matched closely with the corresponding DMD mode obtained from processing the DNS results. For the blunt airfoil, the receptivity of the separating shear layer was suppressed in the region of natural frequency, while it was maximized at the frequency of vortex shedding from the trailing edge. This is attributed to the lock-in mechanism between the shedding and the separating shear layer observed in the DNS simulations; the lock-in makes the separating shear layer less sensitive to forcing. In the tripped flow, the amplification of the perturbations is significantly diminished, and only by restricting the resolvent analysis to a region close to the suction side can we get a dominant frequency that matches with DNS at that region. The dominant resolvent modes were used to get estimations of the velocity spectra based only on the mean
AU  - Thomareis,N
AU  - Papadakis,G
DO  - 10.1103/PhysRevFluids.3.073901
PY  - 2018///
SN  - 2469-990X
TI  - Resolvent analysis of separated and attached flows around anairfoil at transitional Reynolds number
T2  - Physical Review Fluids
UR  - http://dx.doi.org/10.1103/PhysRevFluids.3.073901
UR  - http://hdl.handle.net/10044/1/61256
VL  - 3
ER  -
Download