  In this paper, we present novel identification strategies to develop a
unified framework for vortex-induced vibration (VIV) prediction based on the
general semi-empirical wake oscillator. Greybox nonlinear system identification
method accompanying high-fidelity computational fluid dynamics (CFD) and/or
experimental data could be applied for the identification process. The proposed
template of general wake oscillators contains low- to high-order damping terms
to be identified for characterizing the possible flow dynamics. Two different
strategies, including individual identification of single wake oscillator and
overall identification of coupled VIV control equations, are proposed. VIV
system consisting of an elastically-mounted circular cylinder submerged in
laminar flow at Reynold number of 100 is considered. Both strategies have been
tested and have exhibited high accuracy. The second strategy, i.e., overall
identification of coupled VIV control equations, would be more suitable for the
future framework owing that its training process considers the effect of fluid
damping. A detailed mathematical introduction to future works on framework
development covering the wide Reynold number range is addressed. The proposed
unified framework is a landmark update of past wake oscillators both in terms
of prediction accuracy and physical principles and has considerable research
significance and practical engineering value.
