Imperial College London
Portrait Picture

ProfessorJonathanMorrison

Faculty of Engineering, Department of Aeronautics

Professor of Experimental Fluid Mechanics
 
 
 
//

Contact

 

+44 (0)20 7594 5067j.morrison Website

 
 
//

Location

 

CAGB315City and Guilds BuildingSouth Kensington Campus

//

Summary

 

Publications

Citation

BibTex format

@article{Oxlade:2015:10.1017/jfm.2015.153,
author = {Oxlade, AR and Morrison, JF and Qubain, A and Rigas, G},
doi = {10.1017/jfm.2015.153},
journal = {Journal of Fluid Mechanics},
pages = {305--318},
title = {High-frequency forcing of a turbulent axisymmetric wake},
url = {http://dx.doi.org/10.1017/jfm.2015.153},
volume = {770},
year = {2015}
}
Download

RIS format (EndNote, RefMan)

TY  - JOUR
AB  - A high-frequency periodic jet, issuing immediately below the point of separation, is used to force the turbulent wake of a bluff axisymmetric body, its axis aligned with the free stream. It is shown that the base pressure may be varied more or less at will: at forcing frequencies several times that of the shear layer frequency, the time-averaged area-weighted base pressure increases by as much as 35 %. An investigation of the effects of forcing is made using random and phase-locked two-component particle image velocimetry (PIV), and modal decomposition of pressure fluctuations on the base of the model. The forcing does not target specific local or global wake instabilities: rather, the high-frequency jet creates a row of closely spaced vortex rings, immediately adjacent to which are regions of large shear on each side. These shear layers are associated with large dissipation and inhibit the entrainment of fluid. The resulting pressure recovery is proportional to the strength of the vortices and is accompanied by a broadband suppression of base pressure fluctuations associated with all modes. The optimum forcing frequency, at which amplification of the shear layer mode approaches unity gain, is roughly five times the shear layer frequency.
AU  - Oxlade,AR
AU  - Morrison,JF
AU  - Qubain,A
AU  - Rigas,G
DO  - 10.1017/jfm.2015.153
EP  - 318
PY  - 2015///
SN  - 0022-1120
SP  - 305
TI  - High-frequency forcing of a turbulent axisymmetric wake
T2  - Journal of Fluid Mechanics
UR  - http://dx.doi.org/10.1017/jfm.2015.153
UR  - https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/highfrequency-forcing-of-a-turbulent-axisymmetric-wake/FCE8FA105B14246D5B01ABC9D2F64045
UR  - http://hdl.handle.net/10044/1/23547
VL  - 770
ER  -
Download