Dyanimcs of the wake behind an oscillating and rotating sphere in uniform flow
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2016
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Abstract
The primary objective of the current research is to reveal the wake dynamics of a simultaneously oscillating and rotating sphere in uniform incompressible flow. To achieve these objectives, an in-house code incorporating: Finite volume method, non-staggered arrangement of variables, non-uniform cartesian grid, non-inertial frame of reference, distributed memory allocation parallelization, ghost-cell immersed boundary method (GCIBM), SIP preconditioned BiCGSTAB linear solver is employed. The parameters employed for only oscillating sphere in uniform flow are: Reynolds number (Re=300), normalized oscillation amplitude (A=0.5) along the transverse direction and frequency ratio (0.16≤fR≤1.3). Effects of simultaneous rotation on an oscillating sphere are considered at normalized angular velocity (α=1.2) along the three primary directions (x, y, z) at fR=1.3 and 0.8. Time signals of the force coefficients their frequency spectra, instantaneous vorticity and wake structure are analysed to reveal the underlying physics. Following may be considered as the contributions: 1) enhancing the capabilities of a previously reported GCIBM, 2) revealing two forcing mechanisms with their impact on energy transfer for forced oscillation of a structure in uniform flow, 3) finding similarity between the wake modes for forced and free oscillation of a sphere in uniform flow, 4) observing different flow features for simultaneous oscillation and rotation of a sphere
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Supervisor: Arnab Kumar De
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MECHANICAL ENGINEERING