Third M.I.T. Conference on Computational Fluid and Solid Mechanics June 14–17, 2005  

Receptivity of a low Reynolds number Bickley jet to harmonic vortical excitation

S.K. Sircara,*, T.K. Senguptab
aDepartment of Mathematics, IIT Kanpur, Kanpur, U.P.-208016, India bDepartment of Aerospace Engineering, IIT Kanpur, Kanpur, U.P.-208016, India

  Full Text
The receptivity of a Bickley jet to a time-harmonic symmetric (S-class) and anti-symmetric (AS-class) vortical excitation is reported. Unlike wall-bounded flows, the eigen-spectrum of jets reveals the presence of multiple dominant modes. The S-class displays the presence of upstream propagating disturbances. It is reasoned that, due to the limited streamwise extent of the domain, experiments and computations on round jets do not always correlate with the linear stability properties. For DNS, a new compact scheme (OUCS4), introduced in [1], along with RK4 time stepping is used. A new filtering procedure is advocated in the radial direction, which removes the numerical instability at the core (due to a mathematical singularity) and allows us to study the receptivity of round jets to different classes of excitations.

Keywords:  Bickley jet; CAA; DNS; DRP; Eigen-spectrum; Filtering techniques; Viscous instability

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