Imperial College London


Faculty of Natural SciencesDepartment of Mathematics

Chair in Applied Mathematics







753Huxley BuildingSouth Kensington Campus






BibTex format

author = {Fosas, de Pando M and Schmid, PJ},
doi = {10.1080/14685248.2017.1284325},
journal = {Journal of Turbulence},
pages = {338--351},
title = {Optimal frequency-response sensitivity of compressible flow over roughness elements},
url = {},
volume = {18},
year = {2017}

RIS format (EndNote, RefMan)

AB - Compressible flow over a flat plate with two localised and well-separated roughness elements is analysed by global frequency-response analysis. This analysis reveals a sustained feedback loop consisting of a convectively unstable shear-layer instability, triggered at the upstream roughness, and an upstream-propagating acoustic wave, originating at the downstream roughness and regenerating the shear-layer instability at the upstream protrusion. A typical multi-peaked frequency response is recovered from the numerical simulations. In addition, the optimal forcing and response clearly extract the components of this feedback loop and isolate flow regions of pronounced sensitivity and amplification. An efficient parametric-sensitivity framework is introduced and applied to the reference case which shows that first-order increases in Reynolds number and roughness height act destabilising on the flow, while changes in Mach number or roughness separation cause corresponding shifts in the peak frequencies. This information is gained with negligible effort beyond the reference case and can easily be applied to more complex flows.
AU - Fosas,de Pando M
AU - Schmid,PJ
DO - 10.1080/14685248.2017.1284325
EP - 351
PY - 2017///
SN - 1468-5248
SP - 338
TI - Optimal frequency-response sensitivity of compressible flow over roughness elements
T2 - Journal of Turbulence
UR -
UR -
VL - 18
ER -