Optimal frequency-response sensitivity of compressible flow over roughness elements*

Miguel Fosas de Pando, Peter J. Schmid

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


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.
Original languageEnglish (US)
Pages (from-to)338-351
Number of pages14
JournalJournal of Turbulence
Issue number4
StatePublished - Apr 3 2017
Externally publishedYes

Bibliographical note

Generated from Scopus record by KAUST IRTS on 2022-09-13

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Mechanics of Materials
  • Computational Mechanics
  • Condensed Matter Physics


Dive into the research topics of 'Optimal frequency-response sensitivity of compressible flow over roughness elements*'. Together they form a unique fingerprint.

Cite this