Onset of temporal dynamics within a low reynolds-number laminar fluidic oscillator
نویسندگان
چکیده
We investigate the onset of temporal dynamics a fluidic oscillator (FO) in laminar regime at very low Reynolds number (Re=Uhi/ν, where U and hi are velocity channel height inlet, ν is kinematic viscosity fluid). Both two- spanwise-periodic-three-dimensional simulations performed using high-order spectral element methods to characterise flow inside FO cavity outcoming jet. While remains steady symmetric for sufficiently Re, two-dimensional undergoes symmetry-breaking Hopf bifurcation ReH2=75.7 that results space-time periodic solution. The remnant symmetry later broken pitchfork limit cycles ReP2=294.2. Taking three-dimensionality into consideration an early spanwise-invariance disruption about Re3≃68 wavelength 13hi retards oscillation ReH3=82.1. This effect little representative actual implementations, which typically much narrower than spanwise instability observed these Re. Contrary what happens with FOs turbulent oscillatory regime, frequency output jet found decrease mechanism drives oscillation, however, same: as high speed attaches one internal walls through Coandă effect, feedback channels divert part momentum back, pushes incoming against opposite wall. alternate deviation or other side flipping pressure contribution net end be double advective flux time-periodic but both become comparable Re increased. sweeping angle amplitude more pronounced compared three-dimensional fixed given being only partially fulfilled latter case. In cases sweep increases jet, becomes slightly chaotic already responsible triggering earlier it would, should outside noise suppressed altogether.
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ژورنال
عنوان ژورنال: Applied Mathematical Modelling
سال: 2021
ISSN: ['1872-8480', '0307-904X']
DOI: https://doi.org/10.1016/j.apm.2021.01.044