Open AccessCycle-to-cycle flow variations in a square duct with a symmetrically oscillating constriction
Author(s) -
Erica Sherman,
Lori Lambert,
Bethany White,
Michael Krane,
Timothy Wei
Publication year - 2019
Publication title -
fluid dynamics research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 50
eISSN - 1873-7005
pISSN - 0169-5983
DOI - 10.1088/1873-7005/ab52bf
Subject(s) - strouhal number , mechanics , physics , reynolds number , particle image velocimetry , duct (anatomy) , vortex , oscillation (cell signaling) , flow separation , classical mechanics , turbulence , medicine , pathology , biology , genetics
Spatially and temporally resolved Digital Particle Image Velocimetry (DPIV) measurements are presented of flow complexities in a nominally two-dimensional, symmetric, duct with an oscillating constriction. The motivation for this research lies in advancing the state-of-the-art in applying integral control volume analysis to modeling unsteady internal flows. The specific target is acoustic modeling of human phonation. The integral mass and momentum equations are directly coupled to the acoustic equations and provide quantitative insight into acoustic source strengths in addition to the dynamics of the fluid-structure interactions in the glottis. In this study, a square cross-section duct was constructed with symmetric, computer controlled, oscillating constrictions that incorporate both rocking as well as oscillatory open/close motions. Experiments were run in a free-surface water tunnel over a Strouhal number range, based on maximum jet speed and model length, of 0.012 - 0.048, for a fixed Reynolds number, based on maximum gap opening and maximum jet speed, of 8000. In this study, the constriction motions were continuous with one open-close cycle immediately following another. While the model and its motions were nominally two-dimensional and symmetric, flow asymmetries and oscillation frequency dependent cycle-to-cycle variations were observed. These are examined in the context of terms in the integral conservation equations.