Input-output analysis of the 2D/3C model in channel flows of viscoelastic fluids

Nazish Hoda, Mihailo R. Jovanović, Satish Kumar

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Energy amplification in streamwise constant channel flows of viscoelastic fluids is studied from an input-output point of view by analyzing the responses of the velocity components to spatio-temporal body forces. These inputs into governing equations are assumed to be harmonic in spanwise direction and stochastic in the wall-normal direction and in time. An explicit Reynolds number scaling of frequency responses from different input to different output components is developed. It is found that some of the components of frequency response peak at nonzero temporal frequencies. This is in contrast to the Newtonian fluids, where peaks are always observed at zero frequency, suggesting that viscoelastic effects introduce additional timescales and promote development of flow patterns with smaller time constants than in Newtonian fluids. The frequencies, corresponding to the peaks in the components of frequency response, decrease with an increase in viscosity ratio and show maximum for non-zero elasticity number. At low Reynolds numbers, the energy density decreases monotonically when the elasticity number is sufficiently small, but shows a maximum when the elasticity number becomes sufficiently large, suggesting that elasticity can amplify disturbances even when inertial effects are weak.

Original languageEnglish (US)
Title of host publicationProceedings of the 47th IEEE Conference on Decision and Control, CDC 2008
Pages841-846
Number of pages6
DOIs
StatePublished - Dec 1 2008
Event47th IEEE Conference on Decision and Control, CDC 2008 - Cancun, Mexico
Duration: Dec 9 2008Dec 11 2008

Publication series

NameProceedings of the IEEE Conference on Decision and Control
ISSN (Print)0191-2216

Other

Other47th IEEE Conference on Decision and Control, CDC 2008
Country/TerritoryMexico
CityCancun
Period12/9/0812/11/08

Keywords

  • Input-output analysis
  • Reynolds-number scaling
  • Transition to turbulence
  • Viscoelastic fluids

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